THE WAYBACK MACHINE: The most distant object known appears as a red smudge in a deep Hubble survey of a small patch of sky.
Image: NASA, ESA, G. Illingworth (UCO/Lick Observatory and University of California, Santa Cruz) and the HUDF09 Team
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Astronomers claim to have identified a galaxy in the distant universe that is farther away than any known object in space. The galaxy is so far away that, inasmuch as researchers can see such a faint object, they see it as it looked about 13 billion years ago, just 600 million years or so after the big bang; the light it emitted at that time is only now reaching Earth.
Cosmologists gauge cosmic distances by measuring redshift, a gauge of how much an object's emitted light has been stretched in wavelength during its journey across an expanding universe. The new object, which goes by the unmemorable name of UDFy-38135539, has a redshift of 8.55, topping the previous record holder, a short-lived gamma-ray burst detected in 2009 that had a redshift of about 8.2. The difference in redshift between the two objects corresponds to peering a few tens of millions of years deeper into cosmic history, inching observational astronomy ever closer to the universe's chaotic birth and infancy. Moreover, studying galaxies at high redshifts can bring out details about the epoch of reionization, when light from the first stars and galaxies broke apart neutral hydrogen in the intergalactic medium.
Matthew Lehnert of the Paris Observatory and his colleagues selected UDFy-38135539 from an ultra-deep survey of a small patch of sky made by the Hubble Space Telescope in 2009, shortly after the orbiting observatory had been refurbished with a new camera called Wide Field Camera 3, or WFC3.
The WFC3 survey identified several promising candidates for extremely distant objects, but their true nature remained unclear without follow-up observations. In the October 21 issue of Nature Lehnert and his colleagues report confirmation of the object and a precision estimate of its redshift, thanks to spectroscopic measurements taken at the European Southern Observatory's Very Large Telescope (VLT) in Chile. "Before we took this spectrum, there were only two data points," Lehnert says. "That's not a lot of information." (Scientific American is part of Nature Publishing Group.)
With a more detailed spectrum, astronomers can look for the specific location of Lyman-alpha emission, associated with a transition between energy levels in hydrogen, the most common substance in the universe, as a marker of how much the object's light has been redshifted. For an object as distant as UDFy-38135539 the Lyman-alpha photons have been shifted all the way from the ultraviolet, past visible light, and into the infrared.
James Dunlop, an astrophysicist at the University of Edinburgh's Royal Observatory, notes that UDFy-38135539 is the most distant spectroscopically confirmed object of any kind, despite being a rather mundane galaxy and not a freakishly bright object such as a quasar or a one-off cataclysm such as a gamma-ray burst. At the same time, the detection of a faint Lyman-alpha emission in the spectrum is not unshakable, says Dunlop, who co-authored a paper earlier this year identifying candidate high-redshift galaxies in the Hubble images. "I'm pleased to see this coming because it's so close to what we predicted," he says. "On the other hand, as the authors admit, it's been a real struggle to convince themselves that this line is real."
Earth's atmosphere absorbs many wavelengths of infrared light and contributes its own contaminating molecular emission, known as airglow, making infrared astronomy a tricky business from the ground, even at the VLT's arid, high-altitude perch atop Chile's Cerro Paranal. "In the night sky, you have emission features that cause strong, narrow lines in your spectrum," Lehnert says. "If your astrophysical emission line falls on one of those, then you're doomed."
At the redshift inferred for UDFy-38135539, the hydrogen line happens to fall in a quiet part of the infrared spectrum, but the signal-to-noise ratio leaves some open questions. "It's right on the edge of what you'd believe, to be frank," Dunlop says, noting that confirmation would be much easier with a space-borne infrared spectrograph such as that planned for NASA's James Webb Space Telescope (JWST). But that technology will not be available until JWST launches in 2014, at the earliest. "So you're faced with trying to follow these things up from the largest telescopes on the ground," Dunlop says.
Uncertainties aside, Dunlop credits the researchers for getting solid data on the galaxy with the telescopes available today. "This is two nights integrating on one object with one of the world's best instruments for this stuff," Dunlop says. "It's hard to imagine anyone doing much better with this particular object."
And Lehnert notes that he and his colleagues put their data through a series of statistical tests to try to rule out false positives, a process that he hopes will keep the newly characterized galaxy out of the scrap heap of disputed or retracted claims. "The people that have made these claims that have later been falsified haven't run these tests," he says. "At least if something goes wrong and it's falsified—and I don't think it will be—we can say, 'Hey, we ran every test we could.'"
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Add CommentThe studies of type Ia supernovae that concluded that universal expansion was accelerating (" Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant" , 1998, Riess, et al, http://arxiv.org/abs/astro-ph/9805201v1 ), determined that more accurate distance estimates based on SNe luminosity, for SN more than 5Glya greatly exceeded distance estimates derived from galactic redshifts using standard cosmological models.
Reply | Report Abuse | Link to thisBased on that largely accepted finding, shouldn't the actual distances traverse by light from distant galaxies estimated to be 13Glya based on redshifts using standard cosmological models be much greater?
This would seem to indicate that these newly observed galaxies are much further away than the 13 billion light years estimated. However, that result would conflict with the currently estimated age of the universe.
How can this apparent discrepancy between critical observational evidence be resolved? Perhaps I've misunderstood something: if so please explain.
Although the big bang happened 13.7 billion years ago, due to the expansion of the universe in that time, the distance to the light speed limit is 25 billion light years.
Reply | Report Abuse | Link to thisThe most distant objects observed are considered to be about 13Glya. Is this simply coincidental to the currently estimated age of the universe?
Reply | Report Abuse | Link to thisAre you suggesting that photons can be detected that have traversed 25 billion light years since the moment of its light emission?
As I understand, any inflationary expansion of the universe occurred before the initial escape of light. Some additional explanation seems necessary, or at least some reference.
Thank you jtdwyer for your comment. So many deductions about how old objects are and how old the the universe are in conflict to motivate some scepticism. In one calculation I saw our galaxy was older than the postulated age of the universe, around 14 billion years. And how could a rather not-strange galaxy have been formed a mere 600 million years after the birth of the universe, and in addition, what does that make of the idea that distant galaxies so often are quasars, this representing a postulated stage of earliness? Clearly this rather mediocre galaxy is then older than these supposed violent children are? Cosmology is obviously in a kind of kuhnian crisis these days. What will come out on the other side, only the future knows.
Reply | Report Abuse | Link to thisThank you, Andira, for your helpful insight. Yes, I am skeptical, in this case of the conception of universal acceleration described in my earlier citation. I think that requirement for dark energy arose primarily from a misperception produced as we look back in distant time.
Reply | Report Abuse | Link to thisHaving most precisely determined that more distant galaxies are receding away from their observers at a greater rate than nearer galaxies, it was concluded by Riess et al. (1998) that the expansion of the universe is accelerating.
However, those more _ancient_ light emissions indicating greater rates of expansion reflect the expansion rate of the _earlier_ universe. I think those precise SNe observations actually confirmed the previously expected deceleration of the universe.
Perhaps I’m simply looking through the wrong end of the telescope, but I don’t think so…
The value 8.55 refers to the cosmological redshift. When observing a distant galaxy from a younger, smaller universe, does gravitational redshift add to the value? How does an observer differentiate? Are the lines smeared?
Reply | Report Abuse | Link to thisWhen an observer in that distant galaxy looks out, what does he see? In our direction he would see our galaxy 13Glya as it looked 13B years ago. What would he see in the opposite direction? More galaxies that are 13Glya and as old?
Reply | Report Abuse | Link to thisThere is no favored location in the universe. On average they would see other galaxies in all directions, at all observable distances as we do.
Reply | Report Abuse | Link to thisThe light has been travelling for 13.7 billion years, but it has travelled a distance of 25 billion light years. Although the rate of expansion of the universe varies, and is accelerating, it is, and always has been, expanding. A *distance* (not time) of 13.7 billion light years would only hold in a non-expanding universe, and then there would be no red shift.
Reply | Report Abuse | Link to thisAlthough I could not find it without some digging, this came up in a _Scientific American_ article within the last year or two.
Thanks very much: I can understand that explanation in principle (although I still disagree that expansion is accelerating).
Reply | Report Abuse | Link to thisHowever, that explanation seems to conflict with reports that the most distant objects observed are (with this report) no more than 13.1Glya, as determined by applying standard cosmological models to their observed redshift.
Since the luminosity of light emitted by most objects is variable, only for 'standard candles' such as Ia SNe that emit light of consistent peak luminosity can their light's observed luminosity be used to estimate the actual distance that light has traversed since emission.
In the cited report, observations of SNe estimated to be about 5Glya produced peak luminosity based distance estimates that were _consistent_ with the estimates of standard cosmological models based on the redshift of their galactic light.
However, in that report, observations of higher redshift SNe produced peak luminosity based distance estimates that were _much_greater_ than the estimates of standard cosmological models based on the redshift of their galactic light, at around 10Glya.
From this discrepancy, consistent with your explanation, it was determined that the light from more distant objects had been more greatly affected by the expansion of spacetime than nearer objects, thus the light from more distant objects were actually further away than their redshift indicated and 'were expanded away at a greater rate', indicating that the temporal rate of universal spacetime expansion was accelerating.
However, those 'more distant objects' are not contemporaneously observed objects: they are observations of photons emitted long ago into the very _early_universe_ that had been subjected to _increased_expansion_rates_.
The more _ancient_ light emissions, indicating that their light had traversed greater distances than more _recent_ light emissions, in relation to their redshifts, confirm the temporal _deceleration_ of universal expansion.
If I have misunderstood or misrepresented anything, _please_, anyone, explain my error. If not, the universe should be considered to be decelerating, as had been previously expected, consistent with the second law of thermodynamics.
You asked:
Reply | Report Abuse | Link to this"When an observer in that distant galaxy looks out, what does he see? In our direction he would see our galaxy 13Glya as it looked 13B years ago. What would he see in the opposite direction? More galaxies that are 13Glya and as old?"
Always IMO... An observer in that distant galaxy we observed would be perhaps 13 billion years old now; that galaxy likely no longer exist as we observe it, likely having merged with other galaxies, etc.
If an observer in that galaxy had looked in our direction 13G years ago he might have seen our galaxy as it existed at an earlier time in the then smaller universe, but the light he observed could not have followed a path similar to path the light that we now observed.
Likewise, an observer in the precursor to the Milky Way galaxy perhaps 13Gya might have been able to see the precursor to that recently observed distant galaxy as it existed at some earlier age, but not as distant, in a smaller universe.
A contemporary observer in the approximate relative location of that observed distant galaxy might look in our direction and see the precursor to the Milky Way galaxy, as it existed perhaps 13Gya.
In the earlier universe, perhaps 13Gya, even if expansion were now accelerating (IMO it is not: see comment #5 & #12) it is thought that the expansion of the universe was decelerating until 5Gya, when it first began accelerating. As a result, 13Gya the then much smaller universe was likely expanding at a much greater rate than today, despite the presumedly greater gravitational effects in a much smaller, much more dense universe. This combination of conditions seems particularly counter-intuitive, but must have been in effect.
I suspect that light directed to the Milky Way's precursor at that time could have soon reached it. Other light, directed to the direction that the Milky Way's precursor would be expanded, could have been gently curved by the expansion of spacetime, by now radically curved in the intervening years, to reach us now. This can seem particularly objectionable to any reasonable person but I will not attempt to further explain in this comment and cannot in any way prove this suggestion here. I only mention it as 'food for thought'...
I certainly can't answer all of your 'question', but I think it must be considered that despite the earlier universe being smaller and denser than it is today and despite any 'stronger gravitation' in effect, the early universe must have been expanding at a much greater rate than it is today. If the effects of gravitation were greater, the effects of expansion were greater still.
Reply | Report Abuse | Link to thisWhile it might seem certain that light would be extensively gravitationally curved in the denser earlier universe, as I previously suggested perhaps light was also curved by the almost inconceivable expansion of spacetime that must have overcome the enormous effects of gravitation.
And yet, distant galaxies appear to be quite similar to nearer ones...
I can't represent the conditions in effect at earlier times in the context of any mathematical theory, but I think that much of current consensus understanding of the conditions and effect of the developing universe are not particularly well founded. I suspect that we (science) understands far less than we think. But that's just my uneducated opinion...
The article said the galaxy formed 13 billion yrs. ago. It did not say the galaxy is 13 billion light yrs. away. It is much farther than 13 billion light yrs. bec. it is moving away from earth faster than the speed of light. Any astronomical object with redshift greater than 3 has a cosmological velocity faster than light speed.
Reply | Report Abuse | Link to thisIt is a misconception that nothing can travel faster than light. Special relativity prohibits it but general relativity allows it bec. the universe is expanding faster than light.
Based on current cosmological model, the farthest observable object is 47 billion light yrs.
I can find no statement of when this galaxy formed, which I think is essentially indeterminable from the few photons detected. The only information available is the distance traversed and transit time, both derived from the redshifted spectrum of its observed light.
Reply | Report Abuse | Link to thisThe opening paragraph states:
"Astronomers claim to have identified a galaxy in the distant universe that is farther away than any known object in space. The galaxy is so far away that, inasmuch as researchers can see such a faint object, they see it as it looked about 13 billion years ago, just 600 million years or so after the big bang; the light it emitted at that time is only now reaching Earth."
Essentially the only information available concerning this galaxy is its redshift. Astronomers commonly refer to the redshift derived distance to observed objects and treat distance and transit time interchangeably, even in peer reviewed journal articles. This article refers several times to this galaxy being the most distant ever observed. While not specifying any distance.
As I understand, you are correct that established theories and their contextual interpretation of observations do allow the relative recessional velocity of distant objects to effectively exceed the speed of light, depending on which standard cosmological model applied. Recessional velocity is produced by the expansion of spacetime and is distinguished from the independent relative motion of objects.
These discrepancies and even contradictions among common explanations by scientists leads to a great deal of confusion. Some may find the following article helpful: "Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the universe",
http://arxiv.org/abs/astro-ph/0310808
There are a few interesting points regarding the conception of apparent relative velocity for object in expanding spacetime.
Reply | Report Abuse | Link to thisObjects of mass cannot be indepently accelerated to the speed of light since the application of kinetic energy not only produces acceleration but increases effective mass.
The expansion of spacetime does not impart directional momentum to objects (galaxies), as they are not moving in a specific direction: their apparent recession velocities are proportional to their distance from the observer.
It is the intervening spacetime that is being expanded, increasing the distance between objects rather than moving objects in any direction.
As such, the concept of recessional velocities can be considered as a product of misconception: there is no actual kinetic motion of objects that produces their apparent recession.
Again, there is much that is not completely understood.
By the way, it could be instructive to note that the maximum apparent relative velocity of two objects suspended in a medium in that is being radially dispersed from a singular point of origin at the speed of light would be twice the speed of light.
Reply | Report Abuse | Link to thisTo be precise, the galaxy was formed not later than 13 billion yrs. ago. Since it's redshift is 8.55, much larger than 3, it is moving faster than light hence it's distance is greater than 13 Gly. Distance and transit time can be treated interchangably for astronomical objects with redshift less than 3.
Reply | Report Abuse | Link to thisThere is no misconception in general relativity. It is spacetime that is expanding faster than light so there in no increase in kinetic energy of the object moving faster than light relative to another object in spacetime.
The misconception is nothing can travel faster than light whether objects with mass or information. Recent experiments in quantum teleportation show that information can travel faster than light.
Btw, an object at the edge of the observable universe (47 Glya) will have an 'apparent' velocity of over 3x the speed of light since the universe is only 13.7 billion yrs. old.
Reply | Report Abuse | Link to thisThanks. I think that the light spectroscopy indicted that, 13Gya the galaxy was, _at_that_time_, receding away from the Milky way's current recession rate, and that the apparent differential velocity may exceed the speed of light. IMO, this may be true even if neither ever were exceeding the speed of light relative to a universal geometric point origin for spacetime expansion. I realize this is not any consensus view.
Reply | Report Abuse | Link to thisIMO (blissfully ignorant as I am of established perspectives of GR), there is no evidence for any contemporaneous relative velocity, only for the differential velocity of the observed galaxy 13Gya and the Milky Way today.
The observed galaxy cannot be considered to have been receding away from us for 13Gy. We have no evidence for what its 'current' rate of recession is. Even in an accelerating universe scenario, the rate of expansion is expected to have been diminishing for 8Gy before it began to somehow accelerate 5Gya.
As a result, I don't think its possible to determine a 'current' distance to the observed object, which of course cannot be contemporaneously observed.
Your second paragraph (comment #20) seems to restate what I intended to say previously.
I'm not going to attempt tackle the information teleportation subject today, thanks.
IMO, objects perceived to be at the 'current' periphery of the observed universe are identified by observing light that was emitted 13Gya, which reflects the rate of spacetime expansion in effect at that moment, and (depending on how redshift (wavelength expansion) is considered to be physically affected) perhaps the temporally varying rate of expansion or the current rate of expansion.
Reply | Report Abuse | Link to thisIf your 47Glya distance estimate is based on the apparent rate of recession extended over 13Gy, I think it is incorrect. But I'm just guessing. I hope it's clear to you why I think that...
I find the discussion to be very interesting, though. Thanks.
btw, if my guess that your 47Gly distance estimate is a continuation of the apparent recession rate for 13Gy is correct, I would consider it to be an 'extended virtual distance estimate', but still incorrect. I think the correct way to estimate a 'current' would require the actual temporally varying recession rates that occurred from the moment of observation.
Reply | Report Abuse | Link to thisIf space-time is expanding why are galaxies not expanding? If they are how is relative expansion between galaxies possible? Perhaps there is another explanation for the redshift of distant objects that is a function of great distance alone. We are seeing distant galaxies before the solar system was born and long before we were born, and yet our subjective mind reaches back to conceive of an externalized or objective creative event in spacetime. Space and time are concepts derived from measurements taken in creation. Can these a posteriori measurements be raised to a priori status to explain creation? Is there a universal yardstick out there in space? Is there a universal clock?
Reply | Report Abuse | Link to thisThere is another explanation for redshift that is not related to the velocities of observed objects relative to an observer, but to the direct effect of spacetime expansion. In this case most of the apparent velocity of distant objects is illusionary.
Reply | Report Abuse | Link to thisIn this case, the relative velocity of the emitting and receiving objects do contribute to the redshift of light, but only for the short time that a quanta of light is emitted and received.
The majority of distant light's spectrum redshift is directly imparted by expansion as the light wave traverses expanding spacetime. A spacetime expands, the wavelength of light is also expanded. This mechanism directly explains why the magnitude of redshift is proportional to and a product of the distance traversed and the temporally varying rate of spacetime expansion.
This direct physical mechanism of redshifting light accounts for the apparent recession velocities exceeding the speed of light. Light does not continuously stretch for 13Gly between an emitting object and its eventual receiver: in fact light is emitted from supernova for a relatively short duration. The recession velocity of an emitting object cannot be imparted to its light waves for the duration of transit.
There is no geometric point of origin in the universe bec. all motions are relative to the motion of other bodies. There is no center of expansion in the 4-dimensional spacetime. If such center exists, it is in the higher dimension hyperspace.
Reply | Report Abuse | Link to thisThe velocity of astronomical bodies can be computed using special relativity and cosmological model
v = 2c (1 - (1+z)^-0.5)
where v is velocity, c is speed of light, z is redshift
v > c when z > 3
The 47 Gly is based on general relativity and current cosmological model best fit with observations. Velocities and distances mentioned are actual not apparent.
Thanks - your answer is consistent with established relevant theories and analytical models.
Reply | Report Abuse | Link to thisThe formula for the velocity of astronomical objects attributes all redshift of distant light to the recessional motion of the observed object. While this may be generally entirely useful, it ignores any contribution of expansion to redshift. BTW, it also effectively ignores the relative motion of the observer, which is also generally attributed to the observed object. For most analytical purposes this is adequate.
As I understand, the Doppler effect is mechanically the product of the differential relative velocity of the emitter and receiver as well as any motion of the medium.
While not necessary for analytical purposes when considering astronomical objects, I am suggesting that it is the expansion of spacetime that is responsible for mechanically producing the majority of the redshift of distant light. I think this is more mechanically correct, although I realize this suggestion conflicts with established methods, etc.
I'm not qualified, but I think the theory of general relativity addresses the gravitational motions of objects but does not include the later discovery of the universal expansion of innumerable separate galaxies. Within galaxies it is gravitation that determines the motions of objects. I think that universally, there must be at least some energy dispersal process occurring to account for the general expansion of intergalactic spacetime.
I also think that if the universe began as singularity or any much smaller space its expansion has a geometric point of origin.
I realize that observed expansion appears to be omnidirectional, but I think this can be produced by, for example, radial expansion. If one considers the old inflating balloon analogue of universal expansion, the balloon is radially expanding from a geometric point of origin yet any observer contained within the balloon with a limited view can observe only omnidirectional expansion.
Also, I think it's important to realize that the redshift of light does not include any comotion of all observed objects. It would be possible that all the objects we observe represent only a small, local radius of a spherical universe that is in large part expanding in the same direction. Just like the sound of a car horn traveling in the next lane, there would be little Doppler effect imparted; most of the velocity would not be represented.
Otherwise, I agree that you are correctly representing established and applied physics and concede that I am not - thanks.
I'm still not clear what the 47Gly distance represents unless it represents a projected motion of the observed object over the light transit duration.
Reply | Report Abuse | Link to thisLight emitted in the Early universe would be highly redshifted by the extreme early expansion rate, which would not be maintained throughout the light's transit duration. I think the observed object's 'current' distance in indeterminable.
There seems to be some misunderstanding or conflict within physics regarding the distance of observed objects.
Reply | Report Abuse | Link to thisNASA's announcement, “New Gamma-Ray Burst Smashes Cosmic Distance Record”, April 28, 2009, posted at:
http://www.nasa.gov/home/hqnews/2009/apr/HQ_09-088_Swift_Gamma-ray_Burst.html
states: "corresponded to a distance of about 13 billion light-years." It also includes this statement describing the confirmation of the SWIFT satellite's discovery of the then farthest observed astronomical object:
"At the Galileo National Telescope on La Palma in the Canary Islands, a team including Guido Chincarini at the University of Milan-Bicocca, Italy, determined that the afterglow's so-called redshift was at least 7.6. Tanvir's team, gathering nearly simultaneous observations using one of the European Southern Observatory's Very Large Telescopes on Cerro Paranal, Chile, found a redshift of 8.2, later confirmed by the Italian group. This means the burst exploded 13.035 billion light-years away."
This certainly seems to contradict your assertion that:
"The 47 Gly is based on general relativity and current cosmological model best fit with observations. Velocities and distances mentioned are actual not apparent."
I don't know where the problem lies, unless your 47Gly distance is an estimated extended distance as I've described previously.
I think 13.035 Gly is a typographical error. It should be 13.035 Gya (billion yrs. ago). Anyway, for your info just read this cosmology FAQ from UCLA.
Reply | Report Abuse | Link to thishttp://www.astro.ucla.edu/~wright/cosmology_faq.html
Thanks for correcting my sloppiness. You should note that the UCLA Cosmology FAQ section discussing distances of '47Glya' describes what I repeatedly suggested: that the estimated 'actual' distance to the emitting object is extended (apparently only by cosmologists) by its projected continued recession since the observed light emission. Astronomers do not perform this extension for their distance estimates - this is the source of distance discrepancy.
Reply | Report Abuse | Link to thisI may be wrong, but as I interpret the method of 'extension' described, it does not account for any temporal variation in the expansion of the universe (recession velocity). IMO, the resulting estimation cannot be in any way correct. I'm sure that no student of cosmology would ever agree, but I do have >30 years of successful experience analyzing information systems.
Thanks for the clarifying information - it was very helpful in understanding this conflict.
I was wrong about the method of distance 'extention': it does attempt to account for varying rates of expansion through some segmentation method I didn't want to follow.
Reply | Report Abuse | Link to thisIMO, In attempting to estimate the distance the observed object might recede during the transit of its observed emitted light, it must be acknowledged that the expansion of spacetime has increased the distance the light has traversed, which would have otherwise been limited to the initial separation distance between the emitting object and the observer.
It should be assumed that the spacetime expansion imparting the apparent affect of recession to the emitting object during the observed light's transit could not exceed the increase in the observed light's traversal distance. As a result, the 'extended' recession distance could be no more than the light's traversal distance from it emission to detection. In other words, if the object is estimated to be 13Glya based on the redshift of its light, its 'extended' distance must be less than 26Glya. This maximum would include any acceleration or deceleration of spacetime expansion that occurred during the light's transit.
I do make plenty of errors - please correct any you wish, but I also make assertions that disagree with standard interpretations.
Reply | Report Abuse | Link to thisIt is not correct to state that the most distant objects that can be observed are 47Glya. The observational evidence is that they were 13Glya when their observed light was emitted. The cosmological projection of their current distance is at best a very rough estimate, with no direct supporting evidence (despite being based on the best established... speculations and assumptions).
Assuming that the observed objects still exist in some form, their characteristics have almost certainly changed over time and multiple observed objects have likely been merged.
Since the oldest galactic light emissions detected seem to arrive from the spatial periphery of the observed universe, it seems their light must have been spatially dispersed as it traversed expanding spacetime. In this case, even the apparent spatial density of galaxies in the early, denser universe may be an illusionary product of spacetime expansion. IMO, too much is not completely understood to rely completely on conclusions drawn from what seems to be understood.
Light travels at a finite speed so anywhere we look at the universe, we see the past not the present. If we cannot see 47 Gly bec. we only see the past not the present, then we cannot also see the sun bec. it takes 8 minutes for its light to reach our eyes. By this criterion, we can only see objects at zero distance from our eyes.
Reply | Report Abuse | Link to thisOf course the distant object may look very different now from what we're seeing. 47 Gly refers to the present distance of the object. Much is not yet understood in astronomy but the discussion in the FAQ is already understood.
Well, you really lost me there. By what criterion? Either we can detect emitted light or we cannot.
Reply | Report Abuse | Link to thisIn fact we can see the Sun as it was 8 minutes ago and we can see this object as it was 13Gya but we can't see it as it is now, and we cannot therefore confirm by observation where anyone thinks it is at the present moment, if anywhere.
What is thought to be well understood is often obsoleted in the future.
It's reductio ad absurdum. The opposite is true. We can observe distant objects. Otherwise, the sun is not observable. The universe is expanding uniformly in all directions as viewed from earth so we have an idea where the galaxies are. Detecting the light emitted is the criterion for being observable, not seeing it in real time or knowing its precise location in real time.
Reply | Report Abuse | Link to thisI'm a simple guy - don't understand. The observation of objects 13Glya has been confirmed, based on standard cosmological models used to estimate distance from redshift. In comment #14 you stated:
Reply | Report Abuse | Link to this"The article said the galaxy formed 13 billion yrs. ago. It did not say the galaxy is 13 billion light yrs. away. It is much farther than 13 billion light yrs. bec. it is moving away from earth faster than the speed of light. Any astronomical object with redshift greater than 3 has a cosmological velocity faster than light speed."
"It is a misconception that nothing can travel faster than light. Special relativity prohibits it but general relativity allows it bec. the universe is expanding faster than light."
"Based on current cosmological model, the farthest observable object is 47 billion light yrs."
While not a definitive source, Wikipedia/Redshift states:
"There is a distinction between a redshift in cosmological context as compared to that witnessed when nearby objects exhibit a local Doppler-effect redshift. Rather than cosmological redshifts being a consequence of relative velocities; instead, the photons increase in wavelength and redshift because of a feature of the spacetime through which they are traveling that causes space to expand. Due to the expansion increasing as distances increase, the distance between two remote galaxies can increase at more than 3 × 108 m/s, but this does not imply that the galaxies move faster than the speed of light at their present location which is forbidden by Lorentz covariance."
This seems to conflict with your statements.
I think your statements were at least confusing. I would have appreciated your earlier confirmation in response to my repeated suggestions that you were referring to an extended 'current' distance estimate. Better yet you would have more clearly explained your meaning yourself.
"this does not imply that the galaxies move faster than the speed of light AT THEIR PRESENT LOCATION"
Reply | Report Abuse | Link to thisCapitalized are the key words. That means velocity relative to the spacetime within the vicinity of the moving object. Remember it is spacetime that is expanding faster than light, carrying with it nearby objects. The object's velocity relative to another object far away can exceed light speed.
I hope this finally clarifies it.
Wouldn't an observer within the observed galaxy now likely be able to observe the Milky Way galaxy as it appeared 13Glya, apparently receding away at the same velocity we now attribute to the galaxy we observe?
Reply | Report Abuse | Link to thisRemember that it is the accumulating affect of spacetime expansion that is expanding the wavelength of distant light "...rather than cosmological redshifts being a consequence of relative velocities."
Analytically, physics may often treat the cosmological redshifts as an indication of apparent recessional velocity, but it physically represents the proportional effect of spacetime expansion on the wavelength of light.
Your quotation simply means it is spacetime that is expanding fast, not the object relative to local spacetime. Which is precisely what I said.
Reply | Report Abuse | Link to thisYour last paragraph means the same thing. Redshift is the effect of spacetime expansion on light wavelenght and it is evidence of recessional velocity. It is not merely apparent. It is real. The galaxies are receding from us bec. the universe is expanding. The redshift and the microwave background radiation are not illusions. They are evidences of an expanding universe.
Lorentz and Poincare formulated the equations of special relativity before Einstein. Why is relativity credited to Einstein? It is a matter of interpretation. Lorentz and Poincare thought the bizzare effects of special relativity are merely illusions. Einstein said they are not illusions, they are real.
Perhaps I just can't accept the established views, as it seems to me that that statement:
Reply | Report Abuse | Link to this"Rather than cosmological redshifts being a consequence of relative velocities; instead, the photons increase in wavelength and redshift because of a feature of the spacetime through which they are traveling that causes space to expand."
clearly indicates that cosmological redshifts are not a consequence of relative velocities. Perhaps the source is in error and you are correct.
It occurs to me that the expansion effects producing redshift (wavelength extension), in addition to varying in time with expansion, may simply accumulate as light traverses expanding spacetime, resulting in the greater redshift for more distant objects identified by Hubble. as a result:
"Due to the expansion increasing as distances increase, the distance between two remote galaxies can increase at more than 3 x 10^8 m/s, but this does not imply that the galaxies move faster than the speed of light at their present location which is forbidden by Lorentz covariance."
I understand that the observed object is 13Glya; not because of kinetic energy applied to it but because the intervening spacetime has expanded. Its apparent velocity is the product of the velocity of universal expansion.
I approach problems (how the expansion of the universe could be accelerating, in this case) as an information analyst by carefully reexamining the foundational conceptions behind the original conclusions. Being informed that 'you just don't understand' is par for the course, but persistence is the best way to solve difficult problems. I'm very obstinate. Thanks for tying to help, but my objective is not to understand as physicist understand: that produced the problem. You've been very helpful. Feel free to consider me a moron, as you wish.
Not at all. You're very smart for somebody with no formal training in physics, I guess. I hope this simple analogy will clarify the concept.
Reply | Report Abuse | Link to thisConsider spacetime like a river current, a distant galaxy like a motor boat riding the river current, and earth like an observer at the river bank. Special relativity say the boat cannot travel more than 50 mph bec. that's the limit of its motor. But the river current is moving at 100 mph so the boat is also moving at the same speed relative to the observer even if its motor is turned off.
What your wikipedia source is trying hard to explain (not very clearly) is the boat is 'not' really moving bec. if you look closer it is the river current that is moving. True, the boat is not moving relative to the current but it is moving 100 mph relative to the observer.
This does not violate special relativity bec. the boat does not exceed 50 mph (assume that's light speed) relative to the current (local spacetime). So you're right it is not due to the kinetic energy of the body but it is moving faster than light speed nonetheless.
Excellent analogy (although the motor is superfluous) - thanks!
Reply | Report Abuse | Link to thisNow allow me get in a boat on the river just as it forks. I may then observe the first boat as it passes behind a forest, never to be seen by me again.
Knowing that, at last sighting, our relative velocity was some value less than 100 mph, say 20 mph, I might presume to calculate the boat's location by multiplying that speed by the time traveled. Even assuming that each fork followed a perfectly straight course and that both forks of the river continued to flow at the same velocity, if that velocity should be changing, perhaps because the river channels widened, it would be extremely unlikely that a correct 'current' distance could be determined.
Well, perhaps you could create a clearer analogy, but if only the (apparent) relative velocity of the first boat and the current distance to the last sighting was known, critical information required to calculate a 'current' position would be missing.
Does this help you to understand some of my concerns about calculating 'extended' distances to observed objects?
You might also note that, in this example, it is the independently directed but otherwise comoving observer who is actually moved by the river relative to the last observation location.
Hopefully I'm not mumbling too much here...
We know the current distance of the object bec. we can calculate from amount of redshift how much spacetime has expanded. Both observer and object are moving. The rate of recession is also derived from the redshift since the speed of light is constant.
Reply | Report Abuse | Link to thisWhile its often said that general relativity proves that the motion of all objects is relative to each other, I think it may be more correct to say that the only motion that any observer can detect is the motion of objects relative to our own.
Reply | Report Abuse | Link to thisIn a simple case of a universe in which all galaxies are radially receding away from a singular point of origin, that directional motion will be undetectable by an observer within any galaxy. Only the motion of other galaxies from which an observer is receiving light, relative to the motion of the observer, can be detected.
If two galaxies are moving at 90 degree angles from a singular point of origin, their detected light will only indicate the differential relative motions of the two galaxies.
Even if their individual motions had no influence whatsoever on the other, only their relative motion would be detectable.
Sorry I somehow missed your reply earlier. I agree this is the method of estimating the 'current' location used by cosmologists.
Reply | Report Abuse | Link to thisI think that the information actually contained within the redshift of detected light is the amount of expansion encountered along the light's actual path from its moment of emission to our reception.
It is actually our own galaxy that has effectively receded away from the light that was independently directed towards our eventual relative location of reception in expanding spacetime. It is our own relative motion during the light's traversal of expanding spacetime that is contained within its redshift, along with the original separation distance between the emitting and receiving objects.
Presuming that the observed light traversed a linear path through expanding spacetime, the path it actually traversed was a vector intersecting our own effective path of recession away from our own relative location at the moment of light emission, including the original separation distance between the two objects.
Applying that distance traversed to the observed object presumes the reproduction of the original separation distance and direction of recession.
The established method of estimating the 'current' distance to the observed object presumes that its only relative motion subsequent to the observed light emission is continued direct recession away from the observer. At he very least, it must contain the original separation distance (expanding during transit).
IMO, the established method of estimating 'current' distance used by cosmologists is highly speculative and cannot be confirmed through observation.
Yes the redshift contains information of spacetime expansion from the moment the light was created by a star until it is detected on earth. So if it was created 13 billion yrs ago, it contains all the spacetime expansion that occurred in 13 billion yrs.
Reply | Report Abuse | Link to thisIt is wrong to assume that it contains only "the original separation distance" bec. that implies spacetime expansion is discontinuous beyond a particular point in space where the light was created. The expansion goes all the way the current location of the star so you can determine the current distance.
Imagine spacetime as a rubber band. Stretch it 1 inch, that's the moment the star light was created. Then stretch it 2 inches, that's the moment the light was detected. Imagine the tension in the rubber band as the redshift. The tension contains 2-inch stretch information bec. the tension is continuous up to 2 inches. It doesn't stop at 1 inch.
I never intended to infer that original separation distance would not be expanded, but that the recession of the detecting galaxy could not be isolated from the original separation distance.
Reply | Report Abuse | Link to thisThis very difficult to explain because it contradicts established conceptions. If I can draw on the simple inflating balloon analogy, I think it is presumed that light passing between two galaxies can be represented as a point along a line segment between two galaxies that progresses to its destination at the rate of c as the balloon expands at some rate. I think this view ignores the independent direction of light's self propagation.
While the two galaxies are passively floating on the surface of the expanding spacetime, I suggest that light is actively propagating in some predetermined direction, not always on the surface of the balloon. The distance light traverses is not necessarily determined by its position between the two galaxies on the surface of the balloon.
Light can also be independently directed to a future relative location of the passively receding Milky Way galaxy. In this way the distance the light traverses may be greater than the distance between the two galaxies at the moment of detection.
While this seems inconsistent and counterintuitive, it may explain why the studies of Ia SN to precisely determine distance based on luminosity, independent of redshift, has determined that actual distances for high z objects are greater than that indicated by redshift using standard models.
In this scenario, using the inflating balloon, the distance traversed by light may represent the emission point on an early smaller balloon _through_ the inflation to the eventual detection point on the larger balloon. The light's physical path of self-propagation is a diagonal through expanding spacetime between the two passively receding galaxies.
In this case, the traversal distance of light can't be reliably used to directly estimate the recession distance of galaxies during transit.
I think that, in your rubber band-spacetime analogy, spacetime doesn't directly contain any known information regarding expansion; it is only imparted to light. I kind of get the idea, though. Your comments are very helpful.
Light does not have a direction of propagation independent of specetime. That would mean light is travelling in hyperspace. The distance you're referring to is outside the four dimensional spacetime. It is a 5th dimensional geodesic. While this distance can be calculated mathematically using non-euclidean geometry, it is not physically meaningful.
Reply | Report Abuse | Link to thisBtw, as to why luminosity distance estimate appear farther than indicated by redshift, see my blog response to Dr. Sol Aisenberg of MIT.
Reply | Report Abuse | Link to thishttp://www.skeptic.com/eskeptic/10-11-03/#comment-2448
If your blog response is correct then all of the physicists pondering the acceleration of the universe for the past >10 years 'should have known better'.
Reply | Report Abuse | Link to thisThe discrepancy between distance estimates using Ia SNe peak luminosity and 'standard cosmological models' (based on the redshift of the SN host galaxy's light) is the evidence upon which universal acceleration (requiring dark energy) is based.
Please refer to: " Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant" , 1998, Riess, et al,
http://arxiv.org/abs/astro-ph/9805201v1
I agree with you that their conclusion was invalid, but for a much different reason...
I can't agree with you. The propagation of light is independently directed and independently traverses expanding spacetime.
Reply | Report Abuse | Link to thisYou are arguing in my favor. The deviation in distance of luminosity vs. redshift is exactly what you should expect from an expanding universe. If there were no deviation, it is evidence the universe is NOT expanding bec. the luminosity method implicitly assumes a static spacetime. It is valid for approximation of not very large astronomical distances.
Reply | Report Abuse | Link to thisDistant stars appear less luminous bec. of "spreading of light" a decrease in flux, which means less photons per unit area. It is classical electrodynamics. It has nothing to do with decrease in photon energy due to increasing wavelength, which is quantum mechanics. Dr. Aisenberg is confusing classical electrodynamics and quantum mechanics.
All physicists do know better. Note that Dr. Aisenberg is arguing AGAINST dark matter and accelerating universe. He should know better.
Btw, the propagation of light beyond spacetime violates general relativity and has never been observed.
Correction: I mean dark energy, not dark matter.
Reply | Report Abuse | Link to thisYou are arguing against those who proposed the accelerating universe by suggesting that the distance discrepancy between luminosity and redshift is expected and easily explained.
Reply | Report Abuse | Link to thisDisregarding Dr. Aisenberg, I repeat:
The discrepancy between distance estimates using Ia SNe peak luminosity and 'standard cosmological models' (based on the redshift of the SN host galaxy's light) is the evidence upon which universal acceleration (requiring dark energy) is based.
The reported discrepancy was identified only for a group of high-z supernovae that were around 10Glya. The distance estimates for galaxies that were around 5Glya using both SN luminosity and redshift methods were consistent. From that it was concluded that the expansion of the universe began to accelerate about 5Gly ago. Please review the reference.
Meanwhile, I thought the 'tired light' hypothesis was proposed as an alternative explanation for redshift not requiring spacetime expansion.
Even I understand the inverse-square relationship between luminosity and distance. I don't think Riess, et al, included any loss of 'photon energy' in their derivation of distance from luminosity, but please let me know if you disagree after reviewing their analysis.
Btw, the independently directed propagation of light does not require that light propagate 'beyond spacetime', only that it be directed towards the future location of a receiving galaxy, rather than being directed towards its contemporary relative location, being passively transported to the galaxy's future location. It was you that determined that I was suggesting that light somehow exits universal spacetime and then somehow finds its way back to the receiving galaxy...
I read your reference. The discrepancy between redshift and luminosity is a non-issue bec. it is not the basis for the conclusion of accelerating universe and dark energy as falsely assumed by Dr. Aisenberg, which I said was wrong. In the paper, both methods support the accelerating universe bec. the measurements were corrected to make them fit. Any remaining discrepancy was attributed to systematic uncertainty and does not affect the conclusion.
Reply | Report Abuse | Link to thisThe discrepancy you refer to that support the conclusion is the discrepancy between the observations and the non-accelerating universe model. That is the basis for concluding that the universe is accelerating.
The "tired light" hypothesis is wrong and does not explain anything.
General relativity says light and all matter in the universe are embedded in the 4 dimensional spacetime. When spacetime bends, light also bends. This has already been proven long ago. The only way light can be independent of spacetime is if it is propagating in the 5th dimension. Your description of distance using the ballon model is a 5 dimensional geodesic.
I hope this finally clarifies it.
Sorry you've misunderstood. The reference may be very difficult to understand, but my private communications with Alex Filippenko, one of the authors, confirm the interpretation I've given you.
Reply | Report Abuse | Link to thisThe referenced report states:
"The distances of the high-redshift SNe Ia are, on average, 10% to 15% farther than expected in a low mass density... Universe without a cosmological constant."
It is the discrepancy between the more distant (high-redshift) supernovae samples' distance estimates using luminosity and cosmological models estimating their distance using redshift, whereas there was no such discrepancy for nearer supernovae samples, that indicated to the researchers that acceleration of expansion began a little more than 5Gly ago (representing the nearer supernovae samples without acceleration) and is now continuing (represented by the high-z supernovae samples indicating acceleration).
I don't understand your assertion that photons lose energy traversing spacetime, explaining the inverse-square relationship between emission and observed luminosity and distance traversed, unless you were referring to the 'tired light' hypothesis.
As I understand, general relativity described (and it was demonstrated) that light curves in the presence of a gravitational field. In those terms, then, I'm suggesting that cosmological light curves in the presence of the universal field of expanding spacetime.
I suggest that you reconsider the referenced initial report of the accelerating universe, as I assure you that I have correctly represented its findings.
Thanks for your consideration.
I don't know what Alex Filippenko said but I read the paper and I did not see it claim a discrepancy in redshift and luminosity is the basis of the acceleration of the universe. Can you cite the specific page and paragraph?
Reply | Report Abuse | Link to thisThe quotation you gave simply means high-redshift SNe Ia are 10-15% farther than expected from a non-accelerating universe model (without cosmological constant). Therefore the paper concluded a positive cosmological constant (accelerating universe) is needed to make observation and theory fit.
Read page 24 last paragraph. The conclusions of the two methods are consistent. There is a small distance difference but both methods favor an accelerating universe. Page 27 conclusions 1 and 2 say both methods are inconsistent with a non-accelerating universe model and both are consistent with an accelerating model.
I'm referring to the "tired light" hypothesis of Dr. Aisenberg. It cannot explain away dark energy and accelerating universe.
When spacetime expands, light follows the curvature of spacetime. Hence the current distance between a star and earth is the actual path travelled by the light.
Admitidly I'm neither a physicist nor a scholar, so these papers are extremely difficult to interpret. I'm not done yet.
Reply | Report Abuse | Link to thisFor perspective, these studies were originally intended to determine the deceleration rate of universal expansion. That required that both relatively near and distant samples of Ia SNe be observed, to determine the expansion characteristics during at least two periods during the temporal development of the universe. Observation of high redshift Ia SNe only became possible with CCD technology in the 1990s.
A minimum of two temporally divergent samples of expansion conditions is necessary to assess expansion conditions in the early universe and more recently; to determine how they've changed over time.
Btw, the two methods of light curve fitting referred to are used to identify where on the standard luminosity curve of Ia SNe a particular observation is. This is crucial because only the Ia Sn peak emission luminosity is consistent.
There are differences in the observed characteristics of high redshift Ia SNe and those of low redshift Ia SNe, producing different light curves, or luminosity over their brief lives. One difference, for example, is that stars in the Early universe were composed less of heavy elements than stars created more recently...
I am reconsidering my evaluation. One of the problems is that, despite its crucial role in the planned and eventual analysis, there is no clear statement summarizing the results for early and recent light emissions. Secondly, I've not found a statement of the parameters used for high and low redshift samples to produce the observed effects, only the vague specification that a positive cosmological constant.
Btw, as I understand, a positive cosmological constant produces only an _expanding_ universe; the negative deceleration parameter produces an _acceleration_ of expansion. Since they conclude that the initial deceleration switched to acceleration sometime between their ~5Gly and ~10Gly sample groups, the deceleration parameter should initially be positive for the high redshift sample group, switching to negative later - not a capability normally provided for in the model, I think...
As I mentioned, I am reinvestigating: I don't think that either one of us has correct assessment yet, and I still question the researcher's analysis.
Correction: the third from last paragraph last sentence should conclude:
Reply | Report Abuse | Link to this"only the vague specification of a positive cosmological constant and a negative deceleration parameter."
Sure. You don't have to believe the research. Just tell where the researcher is wrong. Thanks.
Reply | Report Abuse | Link to thisWhile I'm continuing to research, perhaps you'd like to explain your misunderstanding of it. You stated:
Reply | Report Abuse | Link to this"Read page 24 last paragraph. The conclusions of the two methods are consistent. There is a small distance difference but both methods favor an accelerating universe. Page 27 conclusions 1 and 2 say both methods are inconsistent with a non-accelerating universe model and both are consistent with an accelerating model."
The two methods being referred to in that section entitled "5.6. Light Curve Fitting Method" were methods used to determine where an observation had occurred in relation to the short period of its peak luminosity. While the peak emission luminosity of Ia SNe can be used as a standard candles to accurately determine distance because it is consistent, the entire period of a SN's increased luminosity is _not_ consistent: only the peak emission period can be used to determine distance. The two methods discussed in the section you referred to were methods used to determine when a SN's luminosity would peak.
Those methods do affect the method of estimating distance from the Ia SN's peak observed luminosity derived from its consistent peak emission luminosity, but has nothing to do with estimating distance using the redshift of SN host galaxy light and standard cosmological models.
You also stated:
"The quotation you gave simply means high-redshift SNe Ia are 10-15% farther than expected from a non-accelerating universe model (without cosmological constant). Therefore the paper concluded a positive cosmological constant (accelerating universe) is needed to make observation and theory fit."
Perhaps you could explain why you thought that a positive cosmological constant produced a model representing an accelerating universe? As I explained, a positive cosmological constant is required to produce a model representing an _expanding_ universe. The acceleration of universal expansion is produced by specifying a negative value for standard cosmological models' deceleration parameter.
These represent only 'turning the knobs' on the model used to estimate distance from the redshift of light such that the observed redshift produces a predicted distance that fits the estimate produced from the observed Ia SN peak luminosity.
The researchers concluded that the universe was initially decelerating, then began to accelerate, for some unknown reason, from 5-10Gy ago (derived from their two sample groups about 5Glya and 10Glya). There is no way using a constant deceleration parameter to produce a temporally varying rate.
OK, I admit it was I who misunderstood the affect of the cosmological constant, which apparently can result in acceleration of expansion - sorry. However, the paper does refer to the use of a negative deceleration parameter to produce the effect of 'current acceleration'. I don't fully understand...
Reply | Report Abuse | Link to thisMore to the point, that quote from the source paper:
"The distances of the high-redshift SNe Ia are, on average, 10% to 15% farther than expected in a low mass density (M = 0.2) Universe without a cosmological constant."
- distinguishes the high-redshift Ia SNe observations from the low-redshift Ia SNe samples. This seems to strongly imply that only the more distant observations indicate the 'acceleration' of expansion.
Going back to my original interpretation, this seems to support the conclusion that since the ancient light emissions indicate increased expansion, while the more recent emissions do not, the data actually indicates only that universal expansion is decelerating.
Can you please explain my error to me, avoiding your previous misleading explanations, such as the acceleration was determined by model results not temporal variations in observational data, etc...
How To Remove Some Of The Mysteries And Errors In The Standard Model Of The Universe
Reply | Report Abuse | Link to thisMany mysteries, such as dark matter and dark energy, in the current standard model of the universe, show that the standard model has many errors and needs serious revisions.
Dark Energy
The Mysterious Dark Energy, for decades has been of concern for scientists, and astrophysicists. The solution is based upon an understanding of the meaning and limitations of the work of Edward Hubble who in the 1900s showed that the fixed stars were actually galaxies at cosmic distances. There were observed blue shifts and red shifts in our close milky way, but other observations showed that the red shifts increased for the remote galaxies far outside the milky way. For the range of distances observed by Hubble he was able to demonstrate that the red shifts increased linearly with distance. However, there is a scientific limit to the use of red shift to determine galaxy distances because the photon energy decreases with distance and cannot be negative.
Decades ago, the apparent need for Dark Energy appeared when the distance was also determined from the observed magnitudes of the associated standard candles, the super novae type Ia (SN Ia) in remote galaxies, The current speculation for the differences (between the distances determined from star magnitudes and the corresponding red shifts) is that the receding motion of the further stars had apparently accelerated and that Dark Energy was needed to exist to power the speculated acceleration. However, the red shift cannot be extended without limit to very, very large distances. These red shifts correspond to an increase in the wavelength of the light due to a reduction of the energy and frequency of the photons. As the photon energy approaches zero with increasing distance it must become non-linear, and never become negative. Therefore the linear Hubble dependence cannot be used for very, very large distances – and this predicts the difference between the distances determined by observed magnitudes and the distances determined by the observed red shifts. Thus there is no proof or need for acceleration, of the supposed expansion so Dark Energy is not needed - and this mystery disappears.
The recent Nobel prize in Physics in 2011 related to the work of Saul Perlmutter, Brian Schmidt, and Adam Reiss on the discovery of the accelerating expansion of the universe should need reconsideration
Sol Aisenberg, PhD
International Technology Group
508/651-0140
Reply | Report Abuse | Link to thisDark Matter
Observations by Vera Rubin for the flat rotation (constant rotation velocities) in spiral galaxies provided insight into the failure of Newton's universal law of gravity to explain observations at cosmic distances without the need for the mystery of Dark Matter to supply the missing gravity to explain the cosmic observations
Using the simple physics equations for (a) the gravitational attraction towards a central mass, G*M/r*r, and the (b) balancing centrifugal force of rotation v*v/r for a velocity v at a rotation distance of r, we get an equation that reduces to G*M=v*v*r. For the case of a constant velocity, we get G*M as a linear function of distance r.
The usual and wrong assumption is to assign the distance to the mass M because “everyone” knows that Newton's law of gravity is a universal law -. although based only on the observed motion of planets in our solar system. The erroneous result is the belief in the need for missing matter, Dark Matter, to supply the necessary cosmic gravity, and decades of unsuccessful attempts to find the Dark Matter.
My suggested and simple solution is to assign the G*M distance dependence to Newton's gravity which is already invisible. This gives a gravitational constant in the new form as, G=Gn+A*r where this new description reduces to Newton's law at small values of r in our solar system, and where the linear term. A*r dominates at cosmic distances. It does not replace Newton's law but just extends it to be also valid at cosmic distances. This also predicts and explains the observed very, very small attraction toward the sun of the NASA Pioneer 10 and 11 space probes in our solar system where linear term A*r becomes very small but not zero.
Sol Aisenberg, PhD
508/651-0140
solaisenberg@comcast.net
saisenberg@gmail.com
saisenberg@alum.mit.edu
Thanks very much for your excellent comments. I generally agree with both, although I have focused primarily on the perceived requirement for dark matter to explain observed spiral galaxy rotational characteristics. My brief, more recent comments, including several very specific technical references, can be found at:
Reply | Report Abuse | Link to thishttp://sciencewithoutfiction.com/uploads/JDwyer.PDF
I'm not really capable of assessing your suggested approach to large scale gravitational evaluations, but I suspect it could provide a simple and effective method of more accurate estimation.
Fundamentally, I think the root cause of the problem lies in the representation of mass distribution used. As you mention, the simple standard equations estimate the gravitational attraction towards a central mass. Very large scale non-spherical distributions of massive objects, such as galaxies, are not 'attracted' to any central mass so much as to nearer, neighboring masses: they are self-gravitating.
It has recently been demonstrated that the rotational characteristics of spiral galaxies can be described using Newtonian dynamics and universal law of gravitation, without dark matter or modified gravity. Please see: Feng & Gallo, (2011), "Modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies", http://www.raa-journal.org/raa/index.php/raa/article/view/858
While the self-gravitating disks of spiral galaxies do not behave as planetary orbital systems, more distant objects at the galactic periphery do independently orbit the Milky Way 'just like planets in the Solar system'. This observation conflicts with the presence of an enormous dark matter halo containing most of the galaxy's mass. Please also see: Bratek et al, (2011), "Keplerian Ensemble Approximation. The issue of motions of Galactic halo compact objects", http://arxiv.org/abs/1108.1629
Thanks again for your excellent remarks!
There are still several uncertainties presumed in the analysis of type Ia supernovae luminosities (used as standard candles in studies that inferred that the expansion of the universe is accelerating). One uncertainty is the effect of metalicity on peak emission luminosity, used to precisely derive distance in the studies that concluded the universe is accelerating. It is currently presumed to have no effect, but the metalicity of more distant type Ia SNe would likely be different from that of nearer type Ia SNe and its effect on peak emission luminosity has not yet been determined. Please see: http://blogs.nature.com/news/2011/08/bright_supernova_one_of_the_ne.html
Reply | Report Abuse | Link to thisThere are no direct observation that show that the red shift is due to the Doppler effect or receding galaxies or the expanding cosmos. If you know of any such observations, please let me and others where to find them.
Reply | Report Abuse | Link to thisAt some far distance the red shift (increasing wavelength and decreasing photon energy)will not be valid because the photon energy can not be zero or negative. Thus the distance of very far SN Ia will be less than distances determined from SN Ia magnitudes. If two measurements differ then one must be wrong. In true science one does not explain errors by introducing mysterious entities such as Dark Energy to also explain unproven expanding velocity.
Sol Aisenberg
If observations and theory differ, then observations (verified) should rule.
Reply | Report Abuse | Link to thisPasting below my latest essay on Dark Energy.
.==========================================
ESSAY V5 RECENT NOBEL PRIZE FOR DARK ENERGY IS WRONG
There are many mysteries in the model of the universe, and the mystery of Dark Energy recently has apparently been solved – resulting in a 2011 Nobel prize in Physics awarded to the three scientists involved, Perlmutter, Schmit, and Reiss.
However it can be easily demonstrated that their solution is incorrect.
Their proposed solution is based upon the differences between the distances determined by the observed magnitudes for very, very remote standard candles and also their distances determined from their observed redshifts.
The light received (star magnitudes) from these standard candles, the type Ia supernovas, and the inverse square decrease of light with distance permits their distance to be determined.
In addition, the observations by Hubble and others demonstrated that the redshift is a linear function of distance and this permits the the determination of the distance by redshift for comparison.
However the observations of the distances by these two methods showed that the distances determined from star magnitudes was greater then the distances determined from the observed redshifts.
The mysterious Dark Energy was wrongly introduced to explain the energy needed to accelerate the supposed expanding velocity of the remote stars beyond the redshift distances.
The problem is due to not really understanding the meaning of the redshift. Because the redshift corresponds to the increase of wavelength of the light photons, these photons decrease in frequency, and their energy decreases towards zero, but can never be zero or below. Thus the redshift dependence on distance has a limit and cannot be accurately used for extreme distances.
Another problem is that it has not been proven by observations of velocity that the redshift is due the Doppler effect associated with the supposed receding velocity.
Additional details on this and other mysteries and errors are provided in an earlier collection of essays, by S. Aisenberg, “The Misunderstood Universe”, © 2009, which is available from Amazon and your library. Editors can obtain a review copy by email request to promotions@iuniverse.com, with your mailing address.
Sol Aisenberg, PhD, Physics, MIT
Natick, Mass.
508.651.0140
saisenberg@gmail.com
"At some far distance the red shift (increasing wavelength and decreasing photon energy)will not be valid because the photon energy can not be zero or negative."
Reply | Report Abuse | Link to this- As I understand, the CMB is thought to represent the initial light emitted during the big bang in the infrared spectrum that has since redshifted into the microwave spectrum. Since this most ancient light's frequency is still > 10^^8 Hz, how could any currently observed light have lost all of its energy?
- As you later imply, the presumedly constant peak emission luminosity of type Ia SNe is used in a very straightforward manner to estimate distance by interpolating from the peak period observed luminosity based on the inverse square dispersal of light.
The studies concluding that the expansion of the universe is accelerating found a discrepancy between type Ia SNe luminosity based distance estimates and distance estimates derived from then-standard cosmological models based on the redshift of light from their host galaxies.
The researchers found that they could align the distance estimates produced by cosmological models with those based on type Ia SNe luminosity, by specifying a positive cosmological constant parameter and a negative deceleration parameter for the specific observations that were in conflict.
Those 'distant' observations were, as I understand, all less than 5Glya (not really extreme distances) - their light had been emitted when the universe was more than 8 billion years old.
Meanwhile, observations nearer than about 1-3Glya, whose light had been emitted more recently, did not exhibit any discrepancy between the two distance estimates. While, if the expansion of the universe is currently accelerating one might expect to find more pronounced discrepancies in observations of nearer objects, it seems that the cosmological effects on the redshift of nearer objects is not sufficient to produce significant discrepancies between the two methods of distance estimation. While I'm neither a physicist nor mathematician this artifact of cosmological model methods seems somewhat suspect.
Please see:
Riess et al., (1998), "Observational Evidence from Supernovae for an Accelerating Universe and a
Cosmological Constant", http://arxiv.org/abs/astro-ph/9805201
IMO, there may be many opportunities to reevaluate the methods used to determine which model parameters might require adjustment to reconcile the results and what their implication might be, but I doubt that a fundamental misconception involving redshift that produced an invalid conclusion.
Regarding your comment #62, "The Mysterious Dark Energy, for decades has been of concern for scientists, and astrophysicists..." As I understand, it was two research reports published in 1998 (one of which is referenced in my preceding comment) that concluded that universal expansion had begun to accelerate about 5 billion years ago, first requiring some separate, unidentified energy or element referred to as 'dark energy'.
Reply | Report Abuse | Link to thisAs I understand, the initial expansion of the universe is thought to have been independent of this other dark energy that only began to effect universal expansion about 5 to perhaps 10 billion years ago. As I understand, prior to that time, it is still thought that the initial expansion of the universe has been decelerating as it was dispersed by expansion, in accordance with the second law of thermodynamics.
I have to take some exception to the implications of the first paragraph of this article:
Reply | Report Abuse | Link to this"...The galaxy is so far away that, inasmuch as researchers can see such a faint object, they see it as it looked about 13 billion years ago, just 600 million years or so after the big bang; the light it emitted at that time is only now reaching Earth."
While certainly the light that is now being detected is "only now reaching Earth" - all light now being detected is only now reaching Earth, Surely, it is not being claimed here that light from this galaxy has _never_ reached the Earth before? If that were the case, these astronomers would have been exceedingly lucky to have found the first photons to ever reach Earth from this galaxy in the long exposure Hubble ultra-deep field observation!
Alternatively, on the days and weeks and millennia preceding the Hubble ultra-deep field observational study photons from this distant galaxy had been reach Earth, but no one collected them for observation.
This seems to leave us with a problem of cosmology: if photons from UDFy-38135539 reached Earth 1 billion years ago, the object by definition should at that time have had to have been 12 billion light years away, since it could not have been emitted before the big bang. That would also imply that the expansion of the universe proceeds at the speed of light, on average, since the time of the big bang.
Surely I'm misunderstanding something fundamental here: can someone more knowledgeable please explain?