This Hubble Space Telescope image shows a collision between two spiral galaxies, NGC 6050 and IC 1179, in the Hercules constellation.
Image: NASA, ESA and HUBBLE HERITAGE
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The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
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"If galaxies are all moving apart at ever increasing speed, how can they collide?"
—J. Gow, Fairfax, Va.
Cosmologist Tamara Davis, a research fellow at the University of Queensland in Australia and an associate of the Dark Cosmology Center in Denmark, brings together an answer:
The dynamics of the universe are governed by competing forces whose influence varies with scale, so local forces can override universal forces in discrete regions. On scales larger than galaxy clusters, all galaxies are indeed moving apart at an ever increasing rate. The mutual gravitational attraction between two galaxies at that distance is too small to have a significant effect, so the galaxies more or less follow the general flow of the expansion. But it is a different story in a galaxy's local neighborhood. There the gravitational attraction can be very significant and the interactions much more exciting.
Dark energy, believed to be causing the acceleration of the expansion of the universe, provides a constant outward force that does not dilute as the universe expands. Pitted against this relentless push is the gravitational pull from the rest of the matter and energy in the universe. Early on, the universe was much denser than it is today, and the attractive force of gravity was winning the battle, on scales both large and small. Clouds of gas condensed to form stars and galaxies, and galaxies drew together to form clusters. If there had been more matter around, the universe might have started to recollapse before it ever had the chance to accelerate. But matter and energy do dilute as the volume of the universe increases, so dark energy slowly came to dominate. Since about six billion years ago (about a billion years before Earth formed), the expansion has, on average, been accelerating.
Nevertheless, the cosmic dance continues. Galaxies that had been pulled together before the universe began accelerating still have the chance to collide. Collectively they form overdense patches of the universe in which gravity still reigns. In our neighborhood the Andromeda galaxy, our largest companion, is actually falling toward us, and we will have our first close encounter with it in just a few billion years' time.
Our local group comprises Andromeda, the Magellanic Clouds and about 35 other galaxies, all of which lie in an even larger cluster called Virgo. Together we will travel through the expanding universe, and we had better learn to like the company any galaxies that have not yet won the gravity war have missed their chance. The universe is now split into pockets of interaction that will drift alone through the expanding cosmos.
Like revelers on a ship, the galaxies in our group will continue to collide and interact in myriad interesting ways, but we will be forever separated from the revelers on other ships sailing away from us in the vast universe.
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38 Comments
Add CommentConsider time as a vector, then things drop into place. Dark matter is not the motivator of our expanding universe as it is not possible for it to interact in isolation with matter within space. Interstellar displacement is a function of the local time(vector) bias which is dependant on local particulate makeup thus making convergence possible.
Reply | Report Abuse | Link to thisDark matter is still something of a hobgoblin in Physics. We can ascribe all sorts of qualities to it, without really even being sure it exists. I sometimes thing that Dark Matter, and Dark Energy, are merely another type of Einstein's Cosmological Constant. They may work mathematically, but that doesn't make them true.
Reply | Report Abuse | Link to this>>timmyt --
Reply | Report Abuse | Link to thisThis statement makes no sense at all:
"Dark matter is not the motivator of our expanding universe as it is not possible for it to interact in isolation with matter within space."
Neither does this one:
"Interstellar displacement is a function of the local time(vector) bias which is dependant on local particulate makeup thus making convergence possible. "
Also, you mispelled "dependent".
Cheers....
It merely seeks to prove that the universe is infinite, as even the most statistically improbable event, multiplied by infinity, becomes probable, even a guarantee...
Reply | Report Abuse | Link to thisDark matter is simply the memories of the Buddhas real life, before he fell asleep and dreamt the universe...
Hehehe
"Dark energy, believed to be causing the acceleration of the expansion of the universe"
Reply | Report Abuse | Link to thisDark Energy? Why some mythical as unyet proven to exist type of energy? Because "Kinetic Energy" doesn't sound as cool and wouldn't get you grant money?
If e=mc2=spacetime, could there be a 'dark time' component to physics? What would that mean? Phil in DC.
Reply | Report Abuse | Link to this"Dark energy, believed to be causing the acceleration of the expansion of the universe"
Reply | Report Abuse | Link to thisDark Energy? Why some mythical as unyet proven to exist type of energy? Because "Kinetic Energy" doesn't sound as cool and wouldn't get you grant money?
It's not called kinetic energy because it is not kinetic energy, but something else entirely. It's not a matter of grant money, but an attempt to accurately describe what is basically an unknown entity.
However, I wish they would explain in ordinary terms why dark energy produces a repulsive force as opposed to an attractive gravitational force like dark matter.
philiplanks -- That's an interesting question! Many have speculated that 'time' is a more fundamental force than previously thought. In fact, the latest theory by Roderich Tumulka shows how all the empirical predictions of quantum mechanics for entangled pairs of particles could be reproduced by a clever modification of the GRW theory (recall that this theory proposes a philosophically realist way to get the predictions of quantum mechanics under many circumstances). The modification is nonlocal, and yet it is fully compatible with the spacetime geometry of special relativity.
Reply | Report Abuse | Link to thisMoreover, his theory introduces a new variety of nonlocality into the laws of nature—a nonlocality not merely in space but in time!
There is so much that they are not telling u.
Reply | Report Abuse | Link to thisThe universe is not expanding (accelerating at that. Kind of makes u wonder, what have they been smoking? ); the the red shift is not caused by the Doppler effect, but rather the Shapiro effect. Hint from Einstein's General Theory of Relativity: "...the speed of a light wave depends on the strength of the gravitational potential along its path". The farther the light source the greater the gravitational potential, and therefor, the greater the Redshift. No Big Bang. No dark or missing matter. "Keep it simple stupid" as the saying goes.
For some reason, scientist love to complicate things. $$$
You'd think that a theory requiring so many imaginary entities to sustain it would have been taken back to the drawing board before now. Surely it is more likely that the theory is wrong than that 96% of the universe is made up of stuff we can't detect. Isn't that akin to saying that the rotational behaviour of galaxies and the perceived acceleration of universal expansion are due to fairies?
Reply | Report Abuse | Link to thisIt is presumptuous of ANY human to assume that what we PERCEIVE with our minds is the end-all, be-all of matter. What the hell do we know? No where near what is actually out there. But, of course, in science, we have always believed what we knew was all there was to know. And yet, we learn new things everyday about the complicated workings of our diverse universe.
Reply | Report Abuse | Link to thisSo there.
What, I wonder, would other readers think of the suggestion that not only was Einstein with his special relativity possibly wrong, but so too might Max Planck have been with his quantum theory? Maybe Newton was right after all. It is just a pity that when the metaphorical apple fell on his head, the penny did not drop at the same time.
Reply | Report Abuse | Link to thisEinstein and Plank between them seem to have led us into ever more fanciful realms of a space-time continuum, a whole family of sub-fundamental particles, an expanding, or contracting universe, just possibly ‘flat’, multiple, parallel universes, worm holes, time travel, etc., etc., ultimately to a ‘big bang’, the idea that it all started with a teaspoonful of explosive dust.
It seems unrealistic that something so enormous, so enduring, so energy dependent as the universe should have been beholden to a momentary indiscretion by some unknown and unknowable miscreant arsonist for its existence. It would seem more sensible, perhaps, if so complex a system had an in-built supply of renewable energy. Possibly it does have, and just possibly that source is gravity, unlimited, inexhaustible, freely, continuously and instantaneously available to all matter everywhere at all times.
Gravity is an inherent, inalienable, fundamental property of matter, which confers upon it the power of attraction to behave in the manner Newton enunciated. If the idea of this simple energy source is accepted, then we may conceive of the universe as nothing more complicated than a two-component perpetual motion machine, comprising just space and matter, only one universe, infinite and eternal, which must forever go on evolving. One standard unit of matter suffices, a fundamental particle capable of assuming the roles of neutron, proton and electron within atoms, an infinite number of them, and space, a continuous medium that offers a miniscule resistance to the motion of fundamental particles, a resistance which varies with the spin and speed of travel of fundamental particles.
Of course, what applies to fundamental particles applies also to structured aggregations of them, matter as more generally familiar to us.
Throughout space, matter is attracted to other matter, which causes it to acquire increasing kinetic energy, and to coalesce into enormous aggregations, galaxies, leaving vast regions of intervening space virtually emptied of matter, dark and cold. Within ‘embrionic’ galaxies a great deal of matter’s kinetic energy is converted into radiant energy of the space occupied, primarily heat. Maximum temperature is reached when loss of kinetic energy equals gain of radiant energy. For the remainder of a galaxy’s lifetime, this initial total store of energy must suffice for all of the energy phenomena experienced, to occur.
As the galaxy ages, its matter slows and its space cools, radiant wave energy dissipating out into surrounding colder, emptier space according to an inverse square law, the complementary return process to Newton’s Law for the initial gain in kinetic energy by matter. In effect, space serves to return the kinetic energy imparted to matter by gravity back towards a wholly potential state of absolutely cold static space, totally inert matter, a state which can never occur, as matter can never be infinitely distant from all other matter, so these cycles must recur over and over again randomly distributed throughout space and over time, matter from the outer extremities of galaxies spiralling out into surrounding space, there to encounter other such matter from other ‘dying’ galaxies.
Physics and chemistry, all science, is concerned with the study and understanding of the infinite variety of energy phenomena that occur naturally, or that man may contrive, consistent with these ever recurring, ever unique galactic cycles.
It would be most interesting to learn the views of other thoughtful readers.
Is it possible that the driving energy of the universe is a gravitational effect created by massive black holes rotating at relativistic rates generating standing gravitational waves of differing fundamental frequencies explaining both the attractive and driving forces? i.e. like the brass ball experiments, in phase waves repel, out of phase waves attract?
Reply | Report Abuse | Link to thisDavid Cota
Reply | Report Abuse | Link to thisIt's like "horten hears a who"
The big bang and the theory of relativity are solid theories.
________________
Todd
Wow - this was a fascinating article - thanks J. Gow of Fairfax, Va. for asking that question. It's very interesting to read about how the Virgo supercluster of galaxies that we are a part of will stay together while we move further and further apart from the other galaxy clusters and superclusters.
Reply | Report Abuse | Link to thisRegarding Dryer's comment:
Moreover, his theory introduces a new variety of nonlocality into the laws of naturea nonlocality not merely in space but in time!
What exactly is nonlocality in space and time mean? That sounds interesting!
I'd like to point out that there is no gravitational "pull" or dark energy "push" according to the standard model of cosmology and Einstein's relativity! Shame on Scientific American for using this terminology. Gravity is not a force of attraction! Gravity is the effect that mass has on spacetime - it warps space and time. The universe is expanding because space itself is stretching/expanding, and galaxy clusters move apart because the space between them is expanding - they are not moving "through" space, but "with" space! Finally, whatever dark energy is, it is not considered to be a "push", but rather the mechanism which causes the expansion of space - there's nothing "pushing" anything anywhere.
Reply | Report Abuse | Link to thisLate in life Einstein doubted that physics could be based on continuous structures in which case, quote: "...my castle in the sky amounts to nothing but so does the rest of modern physics." The only alternative is a discontinuous and synchronous universe. This is clearly indicated by a new way to delineate the structural dynamics of the cosmic order that embraces all possible structural varieties of phenomenal experience. Never explored before, this methodology clearly indicates that the only universal measuring rods available are the spherical inner space of a primary atom with respect to linear external space. Light comes from within atomic processes. Linear time is thus determined by a succession of synchronous atomic space frames linked by light alternating with timeless orthogonal quantum frames that constitute a boundless spatially indeterminate energy field. In other words light comes as series of pulses in a cosmic movie consistent with Plancks constant. Matter is thus both particulate and formless in each primary interval of time. It is particle waves. The movie must be universally synchronous which requires a universal component that intimately binds each atom into spatially independent (and entangled) wholes. Light is independently related to each atom accounting for universal light speed. Synchronous discrepancies come with relative motions accounting for relativistic effects. An alternate explanation of the Red Shift of distant galaxies necessarily results. A small family of quantum forces associated with gravity also results in a new approach to astrophysics and cosmology. Galaxies regenerate their stellar populations. See the website article Gravity, Quantum Relativity & System 3 at www.cosmic-mindreach.com. Other articles there encompass the biological and social sciences as well as physics. The methodology complements traditional approaches to science.
Reply | Report Abuse | Link to thisLate in life Einstein doubted that physics could be based on continuous structures in which case, quote: "...my castle in the sky amounts to nothing but so does the rest of modern physics." The only alternative is a discontinuous and synchronous universe. This is clearly indicated by a new way to delineate the structural dynamics of the cosmic order that embraces all possible structural varieties of phenomenal experience. Never explored before, this methodology clearly indicates that the only universal measuring rods available are the spherical inner space of a primary atom with respect to linear external space. Light comes from within atomic processes. Linear time is thus determined by a succession of synchronous atomic space frames linked by light alternating with timeless orthogonal quantum frames that constitute a boundless spatially indeterminate energy field. In other words light comes as series of pulses in a cosmic movie consistent with Plancks constant. Matter is thus both particulate and formless in each primary interval of time. It is particle waves. The movie must be universally synchronous which requires a universal component that intimately binds each atom into spatially independent (entangled) wholes. Light is independently related to each atom accounting for universal light speed. Synchronous discrepancies come with relative motions accounting for relativistic effects. An alternate explanation of the Red Shift of distant galaxies necessarily results. A small family of quantum forces associated with gravity also results in a new approach to astrophysics and cosmology. Galaxies regenerate their stellar populations. See the website article Gravity, Quantum Relativity & System 3 at www.cosmic-mindreach.com. Other articles there encompass the biological and social sciences as well as physics. The methodology complements traditional approaches to science.
Reply | Report Abuse | Link to thisWhere are the universal measuring rods of the presumed spacetime continuum of general relativity? If they are derived a posteriori from creation, where is the justification for raising them to a priori status to explain creation? If the spacetime continuum is expanding why are atoms, suns and galaxies that are embedded in it not expanding also? If they are then how is it possible for there to be a Red Shift since everything would remain in the same proportion? If matter is compressed in the direction of travel under relativistic velocities, how is the flattened shape of an atom reconciled with quantum mechanics? These are just some of the contradictions implicit in the spacetime continuum assumption of General Relativity. See "Unified Theories, Fantasy & Cosmic Order" at www.cosmic-mindreach.com.
Reply | Report Abuse | Link to thisi say i sa* i s**
Reply | Report Abuse | Link to thiscertainly proves the parallel universe solution to quantum issues
.........is/was darn useful as a metaphor for the heads of humans heads?
or not - as there is never any parallax EXCEPT LOVE?
:)IF NOTHING ELSE
it soooooooo relative
:)
heavy though
cool sh*t
cool article
push pull
hmmm take yr point butt..?
it all syntax till you model it and feelin it?
even then you aint proved nought ~ till you have lived for ever since before time
after time between time beyond time{*} etc
AND THEN HOW WOULD I BELIEVE YOU LESS I DID SAME
FEEL IT?
{*}
ps~
aka{i.e. ~ &OR}
space matter{waveparticles} gravity continuuuuuuuuuuuuuuum
:)
closest WE got is really a re adoption and tweeking of einteins [thrown out] guess[postualation] at some sort of cosmological constant
and what a dude for admitting humbly he must be wrong
despite concenseus
for all dem year - i feel the pain of isolated truth know - ever felt that - like being accused of murder unspecified or drowning alone
full circle ensued and he was closer all them years inbetween
oh heck #
briefly?
for the children
it yin yang like them wise ancients knew all accross planet in one
never tried to look in box
feel it
controls it
or it controls you
chansin power?
einstein blew and as poet knew - "imagination is more important than knowledge" - but carry both through
"god dont play dice" but he can throw you 'coz HIM hold da cups {three and a ball{cool trinity trick ~ remember it ~ i recall}}
:)
anyone for a party animal ever expanding multidimentional balloon{s}
origin of this sticky mess jam we in
Reply | Report Abuse | Link to this~~i must say i am rather partial to the slices of bread{spacetime membranes}
meatyaphor
i like the idea that god clashed the toast at breakfast or/and a speck of butt......er.... in~between
not stricktly accrute
but funny
the children are listening
big bang other wise
i like duality
it everywhere
:)
from paradox to north south pole
oposition
but i here yin yang dem like
switching
quantum
and this whole right handed left handed thing
hhhhhmmmmmmmmmmmmmmmmmmmmm
Roderich Tumulka - i give thanks - interesting dude
Reply | Report Abuse | Link to thisi shall have a look - i give thanks
Reply | Report Abuse | Link to this1
Reply | Report Abuse | Link to thislove
Reply | Report Abuse | Link to this@25Len
Reply | Report Abuse | Link to thisbiguP
empathy da only real
hence 2 must be 1
1 is held between two infinite limits?
:)
Surely what we think as being likely today might prove completely wrong tomorrow... I can think of some examples such as: Earth's flatness, time relativity and the unthinkable possibility of more than a dozen computers all over the world... I don't know whether the concept of dark matter is correct or not but I do believe that there are natural aspects of the universe which are still unknow to us.
Reply | Report Abuse | Link to thisDark matter and dark energy ,if it does exist? Would hang around the zero degree kelvin and plank length zones, maybe! There is "matter" out there, that we cannot see! Just the statement " the empty vaccumn of space" ,doesn't make sense. Come on guy's, what is the number one rule in physics? there's always something and never nothing! If we see nothing, then we need a better camera.
Reply | Report Abuse | Link to thisHopefully this dark matter & energy is just a smaller particle increment of heat/ atomic value and we just need to improve on our existing tools to see it. We are heat beings and all of our tools of measurement to date need one form of heat or other to measure.
If this is a entirely new entity say a foundational particle like the atom. If it holds no atomic values/ heat within it's composition, then we will have a larger hill to climb. How do you see something, that you have no tools to see with. You have no materials to make the tools with.
Along the same genre as this question, when astronomers look at galaxies as they were billions of years ago, I'm presuming they're looking towards the origination point of the big bang. If this is the case, would looking in the direction we are expanding to, allow us to actually see the "end" of the universe? If they can see objects 12 billion years old in one direction, if the Universe is only 14 billion years old, then we only have about 4 billion years between us and the maximum expansion point of the universe.?
Reply | Report Abuse | Link to thisWhat if the universe was in the process of doubling or dividing itself like a simple cell? In order to do this there would need to be a border and porous points through which the existing universe could push part of itself through. We seem to have proved that or decided that Dark Energy / Mass has the ability to move galaxies. So could Dark Energy / Mass be the material; for lack of a better word, that the universe is pushing through this border and it porous points. As the Dark Energy / Mass is pushed through these pores it would accelerate and this acceleration would densify according to E = mc2 or m = E/c2 creating massive bodies; read galaxies, and an alteration in the field continuum where these massive bodies have a less dense space within them. As these galaxies move through these pores the densification of the continuum increases to the infinite and the mass is converted back into Dark Energy / Mass filling up the new universe. The rate at which this process is occurring would be extreme though to an observer located on the event horizon of these pores or ultra-massive black holes the time would be relativistic.
Reply | Report Abuse | Link to thisSuch an explanation would cover the light velocity speeds at which we see other Galaxies speeding away from us, as well as eliminating the idea of a Big Bang . If Dark Energy / Mass exists then it might be possible to see a rate of change of velocity for any object traveling from with in a altered field continuum into a more homogenous continuum which would exist between Galaxies.
if mater is converted into energy dose the universe lose gravity
Reply | Report Abuse | Link to thisif mater is converted into energy dose the universe lose gravity
Reply | Report Abuse | Link to thisVirtually, the abruption of galaxies means the new cosmos has to divide from the old cosmos where we living now.
Reply | Report Abuse | Link to thisThe whole new cosmos has been closing to us, soon we could be a part of a new world, and the dead one will disappear, the galaxy we living now is the last part of old cosmos, of source, it will be gone soon.
So, are you ready follow the guide of God for the whole new world?
Fascinating question. Dark energy is simply a patch placed over a hole in theory. That is, it's simply a mathematical fudge-factor to make equations in current theory blance out. No wonder no one knows what it is.
Reply | Report Abuse | Link to thisthe dark energy phenomena my hinge on a simple vaccum difference, something like the Higg's Field, that gives the added push to attract matter toward the edge. If so, there has to be some critical point where the positive vaccum turns into a negative.
Reply | Report Abuse | Link to thisColliding galaxies occur in a universe that is not expanding. We can prove that the universe is not expanding; the universe only appears to be expanding.
Reply | Report Abuse | Link to thisProof 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. So, as a beam of photons travels for decades thru space the photons attract each other. So, as the photons gradually diverge, they must also lose energy, which is a redshift. Therefore the redshift is not really caused by an expanding universe.
there was a time we had no way to detect radio waves, and therefor had no idea they even existed. to give up on a theory with such promise simply because we haven't developed calculable ways to prove them YET would be irresponsible.
Reply | Report Abuse | Link to thisThe Hubble telescope's picture of the colliding galaxies seems to show three galaxies colliding, why does the description say only two?
Reply | Report Abuse | Link to this