CLIMBING: The cosmic distance ladder, symbolically shown here in this artist's concept, is a series of stars and other objects within galaxies that have known distances. The Spitzer Space Telescope used this ladder to make the most precise measurement yet of the rate of the universe's expansion.
Image: NASA/JPL-Caltech
The universe just got a new speeding ticket.
The most precise measurement ever made of the speed of the universe's expansion is in, thanks to NASA's Spitzer Space Telescope, and it's a doozy. Space itself is pulling apart at the seams, expanding at a rate of 74.3 plus or minus 2.1 kilometers (46.2 plus or minus 1.3 miles) per second per megaparsec (a megaparsec is roughly 3 million light-years).
If those numbers are a little too much to contemplate, rest assured that's really, really fast. And it's getting faster all the time.
American astronomer Edwin P. Hubble first discovered that our universe isn't static in the 1920s. In fact, Hubble found, space has been expanding since it began with the Big Bang 13.7 billion years ago. Then, in the 1990s, astronomers shocked the world again with the revelation that this expansion is speeding up (this discovery won its finders the 2011 Nobel Prize in physics).
Ever since Hubble's initial discovery, scientists have been trying to refine their measurement of the universe's expansion rate, called the Hubble Constant. It's a hard measurement to make.
The new value reduces the uncertainty in the Hubble Constant to just 3 percent, and improves the precision of the measurement by a factor of three compared to a previous estimate from the Hubble Space Telescope.
"Just over a decade ago, using the words 'precision' and 'cosmology' in the same sentence was not possible, and the size and age of the universe was not known to better than a factor of two," Wendy Freedman of the Observatories of the Carnegie Institution for Science in Pasadena, Calif., said in a statement. "Now we are talking about accuracies of a few percent. It is quite extraordinary." [7 Surprising Facts About the Universe]
The new measurement doesn't just tell scientists how fast the universe is expanding, but helps shed light on the mystery of why this expansion is accelerating. Dark energy is the name given to whatever is causing the universe's expansion to speed up. Yet scientists have little idea what it is.
By combining the new value of the Hubble Constant with observations of the universe by NASA's Wilkinson Microwave Anisotropy Probe (WMAP), the scientists were able to make an independent calculation of the strength of dark energy, which is battling against gravity to pull the universe outward.
"This is a huge puzzle," Freedman said. "It's exciting that we were able to use Spitzer to tackle fundamental problems in cosmology: the precise rate at which the universe is expanding at the current time, as well as measuring the amount of dark energy in the universe from another angle."
Spitzer spies the universe in long-wavelength infrared light not visible to the human eye, which allowed it to peer through obscuring dust to the distant universe. The telescope focused on variable stars called cepheids, which are reliable distance indicators because their intrinsic brightness can be calculated based on their pulsing light. If their intrinsic brightness is known, then their distance can be estimated by comparing their apparent brightness, because the farther away stars are, the more their light dims.
"These pulsating stars are vital rungs in what astronomers call the cosmic distance ladder: a set of objects with known distances that, when combined with the speeds at which the objects are moving away from us, reveal the expansion rate of the universe," said Glenn Wahlgren, Spitzer program scientist at NASA Headquarters in Washington.
Spitzer observed 90 cepheid stars, and was able to measure their apparent brightness more precisely than previous studies, leading the way to a more refined measurement of their distances, and the expansion rate of space.
The Spitzer telescope was launched in August 2003, and ran out of cryogenic coolant to chill its instruments in May 2009. Without coolant, the observatory can't see in all the wavelengths it was originally designed for. Since then, however, Spitzer's been running on a second, "warm" mission that's proven fruitful as well.
The new findings are reported in a paper published in the Astrophysical Journal.
- Images: Peering Back to the Big Bang & Early Universe
- Top 10 Strangest Things in Space
- Gallery: The Infrared Universe Seen by Spitzer Telescope
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52 Comments
Add CommentRe: "The most precise measurement ever made of the speed of the universe's expansion is in, thanks to NASA's Spitzer Space Telescope..."
Reply | Report Abuse | Link to thisCatholic apologist Arnold Lunn wrote, in his 1935 book, 'Science and the Supernatural' (Sheed and Ward, Inc., p. 261): "If, on the other hand, the word "universe" means, as it should, the sum total of reality, it is surely absurd to talk about space expanding."
Where is all-of-known-reality going to go to "expand?"
That's because Lunn used the words "universe" and "space" in ways very different from how they are used by cosmologists today. As a lay person (not a scientist), Lunn's is only an uninformed opinion.
Reply | Report Abuse | Link to thisNeither Hubble telescope nor Spitzer or any instrument in any scientific study has ever measured even a single inch of expansion of space directly. What astronomers have measured in their telescope at earth is the red shift ( Expansion of wave length) of light emanated from galaxies billion of light years away from earth and after crossing unknown territory of space spanning into distance of billion of light years. Can any person fathom a distance of billion of light years? Are scientists certain about the conditions of universe spanning into billion of light years thru which light has to traverse before entering telescope?
Reply | Report Abuse | Link to thisFrom detected red shift of such a light, which was emitted billion of light years in past and which has traversed unknown universe distance of billion of light years, scientist infer the expansion of galaxies. Then from the inference that red shift of light implies galaxies are moving away from us, scientists arrive at the conclusion that it is the space which is expanding.
What is the validity of such conclusion regarding expansion of space? it is for the individual concerned to judge.
Further, there are host of issues concerning expansion of space which do not seem to have an easy solution.
Cont. from comment 3
Reply | Report Abuse | Link to thisUnresolved issues of expansion of space
a) At physical level, when space expands, "what is that?" constituents of space which expands? In other words, whether fabric of space comprises of some physical building blocks or space is purely vacuum implying "nothing". In either case, some physical building block or "nothing" should have some existence.
But when we say "nothing" has some existence, "nothing"
will cease to exist as nothing in real sense
b) Space has been expanding since Big Bang. From where additional space has been emerging which appears with expansion?
c)Dark energy or cosmological constant or quintessence have been theorized as energy components required for normal or accelerated expansion of space. With additional expansion of space, additional energy also appears for expansion of space. From where additional expansion energy appears? What is the nature of that energy?
d) With the expansion of space between galaxies, material galaxies are also displaced away. It implies between matter ( of galaxies) and space, there should be some interacting force which serves as binding between space and galaxies. Had there been no such binding, space would have expanded beneath galaxies ( a sort of slipping away) and galaxies would have remained at same location despite expansion of space.
salustri,
Reply | Report Abuse | Link to thisThe implication of your comment is that the definitions of terms are changed for the sake of the convenience of cosmologists. As uninformed as Lunn's opinion may have been, in my research experience, the only "responses" have been to make up stories by using analogies about balloons with dots painted on them and raisin bread rising during the baking process. If there is any empirical evidence for expansion (and there may very well be), it has escaped my notice.
Again, Perlmutter did not prove that the universe is "speeding up".
Reply | Report Abuse | Link to thisPerlmutter measured the supposed distance to a group of galaxies 5 billion light years away by the maximum of the light curve of Type 1a supernovas located in them. The standard distance to the galaxies was derived by looking at their spectrum and observing the Doppler shift. From the Doppler shift, they found a velocity of recession that, by Hubble's Law, placed them 5 billion light years away. There is no indication that supposed relativistic time lag might have been accounted for, that maybe the supernovas were really shorter in length and only looked longer, that they were really not that bright at maximum and erroneously "concluded" to have been brighter. Based, then, on the length of the period to maximum, the distance to the supernovas was determined. And, as Perlmutter himself said, "The galaxies were further away than they should be." And, therefore, they must be traveling faster than the Hubble Law accounts for. Therefore, the universe started accelerating in its expansion 5 billion years ago and that acceleration is occurring today.
If the galaxies are further away than 5 billion light years, then the light must be older than 5 billion years, and the universe must have "started accelerating" earlier than 5 billion years ago.
What explanation is there for the fact that the Doppler shift conforms to the lower velocity of the conventional Hubble Law, which is how they determined that the galaxies "should be" 5 billion light years away, while the galaxies themselves were supposedly moving faster than that?
If the universe is accelerating today, why is the slower, conventional Hubble Law applicable out to the point of the galaxies that are 5 billion or more than 5 billion light years away?
@vinodkumarsehgal, please look up dunning-kruger.
Reply | Report Abuse | Link to thisTo state that any person suffers from dunning-kruger effect, does no amounts to confronting and addressing the issues.
Reply | Report Abuse | Link to thisStars are accelarate to the edge of the universe . They are then lost beyond perception. Most likely fold back to te center.
Reply | Report Abuse | Link to thisDespite the ability to guess and ponder possibilities I must proclaim I am merely a dunsel in regards to the topics under discussion.
Reply | Report Abuse | Link to thisCan, please, whoever is writing this complete nonsense, explain what this matter is expanding into? Can we not accept the only logical conclusion that the universe is universal, so is time, it has always been there, it has no borders, no beginnings and no end. Only limited human thinking that assumes that mortals can only accept mortals is to blame. If we can't think beyond mortality, we just have to learn to accept it. It's there because there is no alternative.
Reply | Report Abuse | Link to thisWe used to argue about the numbers of the wings of messenger angels and the light they carry. Then we started to count the numbers of orbits of messenger electrons and the photons they carry. We used to know that time passes and things change and we now know that universe expands and energetic entropy of things change.
Reply | Report Abuse | Link to thisIf the space between two specific galaxies is expanding, how does that affect the speed of the photons traveling from one to the other? Are they stretched out by the expansion, do they slow down so as not to exceed the speed of light, or do they speed up due to the expansion?
Reply | Report Abuse | Link to thisHow will each one of the above affect the red shift as observed from each galaxy? If the red shift were increased, would it appear that the galaxies are moving away from each other faster than they really are? And, if so, would there be an exponential effect, making it appear that expansion is accelerating?
Does anyone know the answers to these questions?
"... What astronomers have measured in their telescope at earth is the red shift..."
Reply | Report Abuse | Link to thisActually, in this case distances to pulsating Cepheid variable stars was more directly measured using the infrared Spritzer space telescope. As I understand, Cepheid variables pulsate at a frequency that generally very closely corresponds to its mass, which in turn corresponds to its emission source luminosity. Having derived the estimated source luminosity their distance can generally be precisely determined from their observed apparent luminosity.
Since these Cepheid variables were observed in infrared spectra, their observed luminosity was not much diminished by obscuring dust either in their own galaxies, intergalactic space or our own galaxy. As I understand that's what makes this new measurement more precise.
For additional information on how this distance data is used to determine the 'Hubble' constant, please see
http://en.wikipedia.org/wiki/Hubble_constant#Determining_the_Hubble_constant
Especially see the section "Using WMAP data" which concludes discussing and referencing the research upon which this article was based:
Wendy L. Freedman et al. "Carnegie Hubble Program: A Mid-Infrared Calibration of the Hubble Constant." Astrophysical Journal 758 (Oct. 10 2012): 24. doi:10.1088/0004-637X/758/1/24.
http://arxiv.org/pdf/1208.3281v1.pdf
The research report of course describes in (painful) detail observational issues and methods used.
So, as I understand, the (revised) Hubble constant is used, along other parameters such as the cosmological constant), by the equations of the the 'standard' Lambda Cold Dark Matter (L-CDM) cosmological model to derive distance estimates from redshift data.
As I understand: the speed of light is unchanged by expansion; as a light wave propagates through expanding spacetime, the space between each wave (crest or trough) is increased - thus increasing the light's wavelength & imparting redshift. The expansion of spacetime also increases the distance to the light's eventual 'destination', although since all of spacetime is expanding, even if an emitted light wave was originally 'directed' towards object 'A', it will most likely eventually intersect some other object (or none at all).
Reply | Report Abuse | Link to thisI'm certainly no expert, but I think I can clarify some points.
Reply | Report Abuse | Link to thisIn the type Ia supernovae (SNe) studies that originally concluded that the universal expansion is accelerating, they used the presumed consistent peak luminosity of type Ia SNe as 'standard candles' (see my prior comment about the similar use of Cepheid variables) to presumedly determine their precise distance independent of redshift. They then used the then current standard cosmological models to estimate the distance to the SNe's host galaxies based on the redshift of their light.
For the most distant SNe in their sample, about 5 billion light years away, the SNe distances were about 10% further away than their host galaxies. They then adjusted selected model parameters (cosmological constant and deceleration rate) until they could get the models' redshift based distance estimates to match those based on SNe luminosity. They actually supplied a negative value to the deceleration parameter.
It's important to understand that the cosmological model was used to estimate the distance from redshift for each host galaxy, supplying a different deceleration values in each case - essentially varying the deceleration/(acceleration) of expansion for each galaxy (depending on its redshift) until the predicted distance fit the type Ia luminosity based distance.
It's also important to understand that it was concluded that the acceleration of expansion was presumed to have begun ~5 billion years ago simply because that was the most distant observations available. As I understand, later observations extended the sample up to 7.5 billion years ago - they also exhibited the distance discrepancy interpreted to indicate accelerating expansion. In this case, we really don't know when the hypothesized acceleration of expansion began...
Actually, as best I understand anyway, observations of type Ia SNe less than about 2 billion light years away don't exhibit the discrepancy between distance estimates, presumedly because some of the cosmological conditions (model parameters) do not produce significant redshift effects for such 'nearby' observations. I think this means (as you suggested) we can't really be certain that the expansion of the universe is still accelerating...
Not that there's any potential error in these exceedingly complex analyses that hasn't been checked and eliminated, but if, as I suspect, galactic dark matter does not exist, for example, all bets are off...
BTW, please see
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/Hubble_constant#Interpretation
(ref. links omitted)
"Since the Hubble "constant" is only a constant in space, not in time, the radius of the Hubble sphere may increase or decrease over various time intervals. The subscript '0' indicates the value of the Hubble constant today. Current evidence suggests the expansion of the universe is accelerating, meaning that for any given galaxy, the recession velocity dD/dt is increasing over time as the galaxy moves to greater and greater distances; however, the Hubble parameter is actually thought to be decreasing with time, meaning that if we were to look at some fixed distance D and watch a series of different galaxies pass that distance, later galaxies would pass that distance at a smaller velocity than earlier ones."
I think this means that when universal expansion is not accelerating, it's still decelerating...
"as a light wave propagates through expanding spacetime, the space between each wave (crest or trough) is increased - thus increasing the light's wavelength & imparting redshift."
Reply | Report Abuse | Link to thisEven if light has to traverse extra distance ( due to presumed expansion of space), why it should lead to increase in distance between each wave ( crest or trough) implying increase in wave length Or red shift. Extra traversed distance could result in straightforward manner consumption of more time ( with constant speed of light) time instead of increase of wave length.
One more unresolved implication of increase of wave length. Increased wave length implies decrease of frequency or reduction in light energy. When light will pass thru vacuum, where this loss of energy shall be accounted for in order to preserve conservation law of energy
Thanks jtdwyer for highlighting the distance estimates based upon luminosity estimates for Cepheid variables. I had missed this point earlier. But I think on the 'cosmological distance ladder', Cepheid variable luminosity methodology for distance is applicable up to limited distances only. After certain distances, astronomers are required to use SN luminosity or galactic red shift to estimate the distances
Reply | Report Abuse | Link to thisThough article mentions that Spitzer telescope observed some 90 Cepheid stars and measured their apparent brightness but it does not indicate the distance of these stars from earth
Reply | Report Abuse | Link to thisSince spacetime between waves is expanding, how can that not expand the wavelength of light?
Reply | Report Abuse | Link to thisI don't know about the energy accounting, but if energy is expended to expand spacetime perhaps the decrease in light's energy (with other factors) is accounted for.
I understand that Cepheid variables have limited useful range in visible spectra simply because they luminosity is relatively low (unlike type Ia SNe - they're the brightest objects in visible wavelengths). I think that using infrared spectra to observe Cepheids enhances their range of visibility.
I don't know about distances - check the research report I referenced previously.
Here's my theory:
Reply | Report Abuse | Link to this- All matter is "waves". The Universe it the wave.
- At first The Wave was in a form of a "Standing wave." It did not change, so there was no time, no space.
- Something happened to The Wave. For whatever reason it lost the balance and was shredded into gazillion of sub-waves (strings, whatever). This is what we call The Big Bang.
Now to the universe expansion.
The waves that make the matter (the universe) get older and calm down. As the wave calms down, it gets "smaller", and the distance between the wave nodes increases, so it looks like "expansion" to the observer who is himself made of these wave nodes.
If someone could "see" our "universe" from "outside", he would say that our "universe" is always the same "size" (before, during and after the Big Bang, always). Right now he would see that everything inside this "universe" looses energy and gets smaller. And he would entertain the idea that creatures inside this "universe" probably think that their world expands, when in fact they are shrinking :-)
Expansion of wave length of light should arise from loss of energy ( or frequency) and not from expansion of space ( wave length and frequency being reciprocally related).
Reply | Report Abuse | Link to thisEnergy for expansion of space originates from dark energy or primordial expansion energy at Big Bang and not from e.m energy of light.
Yes, I agree that observation of Cepheid stars in IR light by Spitzer can increase penetrating power of observation and enhance their visibility. Had the study of distance estimate of Cepheid stars by luminosity measurement by Spitzer also complimented with distance estimates by red shift measurement studies, it would have increased the validity. In late ninety studies of SNe leading to prediction of dark energy, distances were estimated thru both techniques -- luminosity studies of SNe and red shift of galaxies in which SNe were located. I don't know why this methodology has not been used in Spitzer study of Cepheid stars. May be at relatively shorter distances, at which Cepheid stars are located, no red shift is detectable. But this my speculation. I am not sure.
Come on! If space expands the wavelength of light mustn't that wave traverse greater distance, further diminishing its energy?
Reply | Report Abuse | Link to thisDoesn't the conservation of energy apply within and throughout a given system? Are light traversing spacetime and expanding spacetime closed, discrete, isolated systems? Pooh!
Light is self propagating in nature and it does not entails any energy ( like matter) for its propagation. So why some energy should be entailed from light itself during its normal traverse or additional traverse in expanded space?
Reply | Report Abuse | Link to this"further diminishing its energy?" Space is vacuum. Where diminished energy of light will go?
Space does not expands at the expanse of e.m energy. Had space expanded at the expanse of e.m energy of light, there was no need for scientists to hypothesize expansion energy of Bb or dark energy
@ vinodkumarsehgal (AKA *jtdwyer*). (Excuse-me but I guess that you both are the same person).
Reply | Report Abuse | Link to thisI followed the suggestion that the commenter *RSchmidt* (comment 7) made for you and I looked for *dunning-kruger*, and I what I found is very instructive. See yourself:
http://encyclopedia.thefreedictionary.com/Dunning-Kruger+effect
In the text of this link is stated that:
*They (referring to *Kruger and Dunning * that was awarded with a 2000 Ig Nobel prize*) hypothesized that with a typical skill which humans may possess in greater or lesser degree,*. . .
*(item) 4. If they can be trained to substantially improve their own skill level, these individuals can recognize and acknowledge their own previous lack of skill.*
The reading of that text could be useful to you *vinodkumarsehgal*, alias *jtdwyer* that demonstrate very interest in astrophysics and are extremely prolix.
Human mind has a very peculiar feature. When it builds an opinion about any thing or a person based upon some pre-conceived notion, it is very very difficult to reverse that opinion. A live example of this peculiar feature is your above comment and comment of R Schmidt. My self and jtdwyer are not the same person. Though we have interacting with each other under the columns of SA and for some time we also interacted thru personal mails , but we have never met each other and we are located thousand of miles across the Globe.
Reply | Report Abuse | Link to thisReaders on the forum of a reputed magazine like SA should learn to trust others.
Before posting my comment #8 against comment #7 of R Schimdt, I had gone thru Wiki entry of Krugger and Dunning effect. I admit that before comment of R Schmidt, I had not even heard of this effect. This way comments of R Schimdt benefited me since I became aware of a new cognitive phenomenon. However, comments of R Schmidt#7 and now your comments # 26, though imparting an instructive advice to me, amounts to outskirting issues as raised by me at comment# 3 and 4 rather than confronting the same. I wish some cognitive scientist could have also studied about building of opiniosn based upon pre-conceived notions also.
So much said. when I am raising a basic issue : "why expansion of space should lead to expansion of wave length of light? " -- how " Krugger and Dunning effect" has come in picture.
Expansion of wave length ( red shift) amounts to same thing as reduction in frequency ( or energy) of light. When energy for expansion of space does not come out of the e.m energy of light, why expansion of space should lead to reduction in energy of light?.
Of course jtdwyer has tried to explain the red shift due to lengthening of wave length since light has to traverse extra distance. This explanation seems to stem from an instinctive analogy of a child who has to cross a distance between two points distant 1 mile with each step of 12 inches in a time span of 60 minutes. Now if due to expansion, child has to cover a distance of 1.5 miles, his step may increase to 13 or 14 inches in order to cover the higher distance of 1.5 miles. But any explanation for increase in wave length due to expansion of space based upon above analogy is not correct. Reason being scientists are not yet sure if there is any actual dimensional spatial spacing between crests or troughs in an e.m wave. Further why expansion should lead to increase of step ( wave length) rather than increase of time?
So you have another explanation to put forward for explaining expanding wavelengths of light through space. You're saying they don't know what they're talking about. You must know the answer as you are saying you do know that they are wrong. So what is the answer?
Reply | Report Abuse | Link to thisZexks,
Reply | Report Abuse | Link to thisFor me, the answer is patently simple; the universe is not expanding since there doesn't seem to be any place for it to "go" to expand. As for the "expanding wavelengths of light through space" (i.e., redshift interpreted as Doppler Effect allegedly causing recessional velocity) that interpretation could very well be incorrect. Astronomer Halton Arp has photographic evidence of high-red-shift quasars luminously connected to low-red-shift galaxies.
@ vinodkumarsehgal
Reply | Report Abuse | Link to thisI'm no expert by any means, but to me the answer seems to be very simple: Light has a lower frequency because it has less energy because at a given distance you have less photons "hitting" your "lens"/eye at any given moment. And that happens because as speed increases the photons that are created "later" take more time to reach their destination... This is my explanation, but I might be incurring in a basic mistake related with relativity...
I am a total noob when it comes to physics and Astrology but I had a couple of thoughts that may be completely idiotic and I am more interested in being informed than being right about anything.
Reply | Report Abuse | Link to thisOne of my thoughts was:
What if the universe is spinning ridiculously fast and the reason we don't see any lateral shift is because time is distorted with that spinning and makes it seem like forces are moving uniformly outward? Perhaps the spinning would provide the force to accelerate things outward combined with my other thought...
Which is:
Is it possible that, at the edge of the galaxy, things are moving so fast and with so much energy that they create an attractive force. If mass and energy are directly related is it possible that if the initial Bang, unlimited in its outward momentum by friction or other forces acting on its outer ridge, could move so fast that it created an infinite growing, self accumulating mass approximating energy? Perhaps it is like an inside out black hole?
My last thought is that it is impossible, as members of this space time continuum, that we could not fully grasp the properties of "nothing". Is it possible that nothing is a vacuous thing that is hungry to be filled in because it is imbalanced with something? Is it possible that something is drawn to nothing like air to a vacuum, because it is ultimately unequal?
Like I said I am a super dummy, eager to receive the thoughts of others who understand this more than me. I tried to read numerous documents on the properties of light and matter and continuously find myself baffled. The person who manages to communicate that in an understandable, yet thorough way, will be a genius in my books.
Dan
I like this concept.
Reply | Report Abuse | Link to thisThere is no relation between frequency of light and nos. of photons. Frequency determines the energy content within each photon. Nos. of photons determine the intensity of light implying total luminosity or energy at some point. Of course, frequency ( energy content) of each photon will also affect luminosity but it will have no impact upon nos, of photons. Similarly nos. photons will not affect frequency of light. I am illustrating this point thru an analogy. Suppose there are 100 bulbs in a room with each bulb of 60 watt. If we may reduce the nos. of bulbs say 80 nos., it will have no affect on the wattage of each bulb. Similarly, if we may reduce the wattage of each bulb to 40 watt, it will have no affect on nos. of bulb. But total light ( energy) emanating from bulbs shall be the combination of wattage of each bub and nos. of bulbs.
Reply | Report Abuse | Link to thisThere is no increase in the speed of photons. all the photons travel at constant speed of light "c"
At first The Wave was in a form of a "Standing wave." It did not change, so there was no time, no space.
Reply | Report Abuse | Link to thisCan a wave exist without space or propagate without time? Does some waves of light from remote galaxies located billion of light years reach earth instantly implying without time?
Proof that the universe is not expanding starts as a realization that photons have gravity. We know photons are affected by gravity, and therefore photons have gravity. Photons travel thru space for billions of years, and since they diverge, and since they attract each other, they must lose energy, which causes a redshift in photon color. Therefore the redshift is not really caused by an expanding universe.
Reply | Report Abuse | Link to thisSince the expansion is an illusion, measuring how much expansion is changing is a measurement of how much an illusion is changing. Extra accuracy of such a measurement does not change the fact that expansion is an illusion.
Thank you very much for your answer.
Reply | Report Abuse | Link to thisYeah... Waves are a bit complicated to understand to me. What I was trying to say was a bit different than what I think you understood. Still, can you answer a question for me. The answer might allow me to understand something basic about photons.
Can you measure the frequency of a single photon, that is, can you measure the frequency of light using a single photon? Since photons have this duality "thing" i can never understand their true nature... And just to compare to something that should be simpler... Can you measure the frequency of a AC using a single electron?
I am not an expert in the field of e.m waves. But as far as my understanding goes, a photon of e.m energy is the fixed content of energy and frequency is the nos. of times e.m field fluctuates per sec. More the fluctuations of field, more the frequency and more the energy content. A photon may carry any amount of energy, but in multiple of Plank constant 'h', depending upon frequency. In view of this, frequency for a single photons also carries meaning. I don't know if scientists have ever measured frequency of a single photon. But one thing about which I am aware with certainty is that scientists have observed wave character for even a single photon around a double slit.
Reply | Report Abuse | Link to thisThere are 3 types of red shifts in Cosmology. Ist Doppler red shift which is caused due to actual movement ( receding away) of a light source from observer. Second one is gravitational red shift which arises when light leaves gravitational red shift of some massive body. These red shifts are easy to interpret. These are different than cosmological red shift, which has been observed for light emanating from galaxies located billion of light years away and which scientist interpret as arising from expansion of space between galaxies.
Reply | Report Abuse | Link to thisAgain thank you for your answer. For what I understood from your answer I got the idea that while you could measure the frequency of a photon if you could follow it during a specific time or space (measuring the changes in the field), you cannot measure the frequency of a photon if your measuring device is statiionary and you only have a single photon to work with.
Reply | Report Abuse | Link to thisUsing a very bad analogy: Let's imagine that you are in a buoy in the middle if the ocean. In a boat, 1 mile away, your colleague has placed a marker in a single molecule of water and then he released that molecule in the ocean. That molecule is moving in your direction. You have a detector that can only mesure the molecule's presence at one specific point in space. If you prefer, you can only get one single measure of the molecule's "info". In this scenario my understanding is that while you can get the molecule's location you could never get the frequency of the waves in which the molecule is moving because it's not possible to get that information from a single measure of a object in a single point in time and space.
In conclusion, what I meant is that while the frequency of a single photon is not affected by the movement of the source, the "frequency" of light ("many photons") is affected by that movement.
Again, I'm sorry if this is completly nonsense, but the only way I can think about a photon is as a particle (something with a finite existence).
Sorry let me correct myself on this. The redshift produces a decrease in the energy of a photon. That being the case, then a simple explanation like the one I gave before makes no sense. Sorry for the mistakes made.
Reply | Report Abuse | Link to thisSince the cosmological red shift of distant galaxies is observed in light which left them up 13 billion years in the past, wouldn't that just mean they were moving away fast then? How can we interpret that to mean they are moving even faster now? Seems to me that only tells us they were moving fast back then and, since closer objects are moving away slower, or not at all, shouldn't we interpret that as proof the expansion is slowing down?
Reply | Report Abuse | Link to thisThe universe is not expanding. Photons have gravity. As photons travel thru space for billions of years, and since they diverge, and since they attract each other, they must lose energy, which causes a redshift in photon color. Therefore the redshift is not really caused by an expanding universe.
Reply | Report Abuse | Link to thisSince the expansion is an illusion, extra accuracy of such a measurement does not change the fact that expansion is an illusion.
Calculation of redshift must utilize the fact that photons are wave-like, and so their "mass" is distributed along the wave. This means that as photons diverge, distributed photon gravity acts upon the distributed photon "mass". Therefore, energy change is similar to that of a spherical vessel expanding and stretching, but maintaining a constant thickness.
Gravity of such a “vessel” is nearly constant, and a function of its mass, since its center of mass does not move, but energy change can be found using the change in radius of the “vessel”, which expands in the gravity field.
Photons have gravity?? Where did you read that from. This is the first time I ever heard that one. If that's true then that means they have mass?? Not "relativistic mass" but "rest mass"?? And if that's the case then they cannot move at the speed of light, since a basic principle of relativity tell us that noting with mass can move at C. Can you explain to me where my though process is wrong?
Reply | Report Abuse | Link to thisThe universe is not really expanding. Redshift is actually caused by an energy decrease as a photon expands. First, we must realize that a photon has gravity since we know that gravity bends light. Second, as a photon travels thru space for billions of years, it diverges, and since it attract itself, it must lose energy, which causes a redshift in photon color.
Reply | Report Abuse | Link to thisSince a photon is wave-like, and its "mass" is distributed along the wave, as a photon diverges, energy change is similar to that of a sphere expanding and stretching in its own gravity field. After billions of years in space the amount of stretching is incredible.
Well, I actually thought you had a honest opinion on the subject, but since you decided not to answer the questions that I asked and, even worst than that, you said " First, we must realize that a photon has gravity since we know that gravity bends light". That's completly wrong because light is not bended by gravity, space is, and since light travels along space that means that light will be affected by the curvature of space not by the force of gravity. Again, the understanding today is that a photon has no mass. If that was not the case then light couldn't travel at C.
Reply | Report Abuse | Link to thisFor a photon coming from a very distant star, a photon must diverge or expand against its own gravity. The “expansion” happens gradually as the photon travels. Since it attracts itself, it must lose energy, which causes a redshift in photon color.
Reply | Report Abuse | Link to thisA comment on "hugoal" comments: I used "mass" in my comment not mass. A photon has equivalent "mass" since that is due to the energy of the photon.
Ok... so you meant "relativistic mass". That's fine and it's a fact that a photon has that "mass". The only problem is that gravity is caused by "real" mass. not relativistic mass. Relativistic mass is not mass in the commom sense and for that reason you cannot say that "Since it attracts itself, it must lose energy, which causes a redshift in photon color". You still haven't show any kind of basis for your statements, I have to assum that your only saying things because you think they might sound good. If I'm wrong, please show me why...
Reply | Report Abuse | Link to thisOk... so you meant "relativistic mass". That's fine and it's a fact that a photon has that "mass". The only problem is that gravity is caused by "real" mass. not relativistic mass. Relativistic mass is not mass in the commom sense and for that reason you cannot say that "Since it attracts itself, it must lose energy, which causes a redshift in photon color". You still haven't show any kind of basis for your statements, I have to assum that your only saying things because you think they might sound good. If I'm wrong, please show me why...
Reply | Report Abuse | Link to thisI think there is another reason why the universe is not really expanding. Redshift is actually caused by an energy decrease as a photon travels thru space for billions of years. First, we must realize that a photon must have gravity since we know that gravity attracts photons. Second, as a photon travels thru space for billions of years, at the incredible speed of light, it must lose energy since it must emit gravitational waves. The energy loss appears as a redshift in photon color. (See “gravitational wave” in Wikipedia.)
Reply | Report Abuse | Link to thisOk... Now this is just silly. You might think that if you keep repeating the same thing several times you might actually convince someone. Honestly I think you might have the wrong WebSite for that trick.
Reply | Report Abuse | Link to thisFirst you say "First, we must realize that a photon must have gravity since we know that gravity attracts photons." both the premisse and the conclusion are wrong. Then you came up with this: "...it must lose energy since it must emit gravitational waves...". It seems that you have decided that a photon (particle without mass) must emit something that is produced only by objects with mass. Interesting... Anyway, it seems that you are just writing stuff about which you have no idea (or at least you fail to explain were did you derived your conclusions). With that said, please enjoy writing some more statements like these.
That is not an expansion of the universe, it is a contraction. When you think that it is a contraction you can explain why stars go faster since in each second they are closer to the black hole they speed up. We are all the way going down to the black hole and the dark (in night) around us is the sides of its wall.
Reply | Report Abuse | Link to thisYes, many "Authorities", ex. physicists confuse themselves @ others. An example: T.J.Penrose, The Road to Reality, ch.18.3 on relativity: "It is true, that the cloak of a cosmonaut registers shorter the distance of time than the cloak on earth". Really? We, human beings only can measure the the time of life (or the frequency in atomic o'clock) of radiation material once on the EArth and the same time of the same particles in cosmic rays; we conclude, the life time is longer in cosmic particles. The author makes a wrong picture to the above experimental data; he forgets to add that measurements (the speed of cosmic rays, the time life of micro particles on the earth@ in cosmic rays) are made are in reference to the axis system/reference on The Earth! In only thought experiment we can deduce that the same is in vice versa situation, but we cannot now@never done such experiments; therefore, the so called "twin paradox" is just a hoax like "Schrodinger cat" in Quantum Mechanics. M.Schlegel, a friend of Einstein confirms it in his books @cites even Einstein (from 1952) that "the cloak paradox has nothing to do with relativity". Penrose and others by analogy transforms the experimental data with micro "particles" into the time of macro objects like human beings and forgetting that there is NO Absolute System of reference which assumes the so called "twin paradox" in which the time life of the speeding brother is faster than the other- read Schlegel, The Space @Time and others.
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