Slashdot Mirror
NASA: Evidence Favors Infinitely Expanding Universe
Chris Gondek writes "The Sydney Morning Herald has a story here about how NASA is expected to announce this week that it has proved the existence of "dark energy," a cosmic force that counteracts gravity and will keep the universe expanding forever. The announcement will effectively demolish the theory that life will be wiped out in a "big crunch" when the universe collapses, and should end decades of academic dispute. Scientists ranging from Stephen Hawking, the Cambridge University physicist, to Albert Einstein, have argued that the universe eventually will stop expanding and then implode under the force of gravity, destroying all life. The Chicago Sun Times has also got some info."
So instead of the Big Crunch, we get Heat Death. The universe is slowly cooling, and will eventually cool to absolute zero (killing all life), or so the theory goes.
I don't think that there is any reputable theory that doesn't have a "killing all life" at some point in the very distant future.
Well, there goes the whole Omega Point thing. I guess there'll be no subjective eternity of omniciense and omnipotence for the likes of us. Oh, well.
What will remain is a universe full of black holes, which after trillions of years will explode to leave nothing but dark energy.
This is true... unless there is another mechanism that transforms some of the dark energy back to normal matter. This could result in a classic steady state model.
Expansion of the universe doesn't actually mean the space between the atoms in your body increases. The atoms in your body are tightly coupled by strong electromagnetic forces, which are stronger than the expansion of the universe. Imagine a cardboard disc on the elastic surface that usually represents spacetime - several cardboard discs will grow apart as you stretch the surface, but the discs themselves will not grow, they are rigid because of the internal forces.
Those discs are actually of sizes somewhere around clusters of (billions of) galaxies, so the atoms in your body are fairly safe.
Daniel
Carpe Diem
I don't know much about the subject, but couldn't this dark energy that is proven exists one day stop, for any reason? I always thought the expanding was due to the big bang, however if our accelleration is not decreasing, then this would be interesting. If the energy stops pulling us outwards, then it seems like we would be sucked back in for the big bang to start over.
They try to get me to accept the big bang.. but the problem I see is if everything emanated from a point source, it should not have any rotational inertia, which will be required for the spin I observe.
Maybe our observable universe is the result of the explosive contraction of a black hole? Let me elaborate: A black hole forms, and begins to accrete matter. But the matter is not falling *directly* into the hole, no, it goes round and round on its way in, going ever faster as it falls inward, spinning the hole up. Consider under the rotational centrifugal forces, the singularity forms a ring. Eventually, this ring meets the event horizon. Now, as long as the ring is not spinning fast enough to meet the event horizon, the hole is stable, but once the centrifugal force of the singularity exceeds in the tiniest amount the gravitational force holding it together, it looks like it may detonate, much like a wheel would detonate if you spun it faster than the tensile strength of the steel it is made of exceeded.
This would form the local areas we see in the universe as galaxies and galaxy clusters... and as a result of the rotational inertia of the detonating black hole which formed them, they would rotate likewise, and eventually the cycle would repeat. Endlessly. Much like a pendulum - free of friction, constantly exchanges kinetic energy for potential energy.
I'll toss this idea up the pole... comments invited.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
Not with a bang but a whimper
;)
That said, an infinitely expanding (or "open") universe is just as likely to destroy all life as the "big crunch" at the end of a collapsing (or "closed") universe. The open universe eventually winds down as all the energy in the universe become homogenized by the 2nd law of thermodynamics in a fate that is often referred to as "heat death".
If anything, the symmetric fate of a closed universe is usually considered the more hopeful fate of the universe mirroring the more traditional cyclic cosmologies of many cultures. Not only does it allow for a sort of cosmic reincarnation but also provides insight into the origin of our own universe (plus some really interesting theories as to the nature of time).
As I see it, an open universe is going to fuel some interesting debates among proponents of the strong anthropic principle (unless they are also advocates of a mischevious "trickster" creator). At least we can take solace in the possibility that matter-energy lost from our universe is "reborn" through inflation events on the far side of black holes. Otherwise, its all seems to me to be an awfully big waste of space-time
The assumption is that the laws of physics are uniform throughout the universe, which I also assume to be true. However, I don't assume that gravity is an attractive force, but rather one that obeys common sense, and is repulsive in nature at the quantum level.
I believe that when a graviton interacts with a particle, it pushes it along... just like any other particle interaction... but I believe that the source of the gravitons is external... and that each interaction creates a shadow... thus there would be slightly more gravitons coming at be from above, than have managed to pass through the earth to hit me from below... thus creating an apparent (and real) local gravity field, with the deficit in the downward direction.
The experiments to prove this are going to be very sneaky... but one sure proof would be that a material that stops gravitons would be very heavy, instead of having a negative weight. Even if you managed to stop some of the gravitons... then effects would be on the opposite side of the device than expected. Thus if your anti-gravity plate is put underneath a weight, it would actually get heavier... and if you put it above the plate, then it would get lighter.
The truely interesting effects occur when you get black-hole level matter density. If I'm right... then they should probably "boil off" slowly as some of the matter gets pushed out of the hole over time.
--Mike--
It's kind of a funny term. Heat death is actually the complete conversion of all the free energy in a system (in this case, of all systems) into the corresponding entropy. It's the victory of the second law of thermodynamics. It's not that all the energy goes away, but that it becomes so evenly spread that no further work is possible - there are no more free energy gradients to traverse. So it's not the death of heat, it's a death in heat - literally a tepid cosmos. ;)
As I noted in another message, an infinitely expanding universe means that the temperature of the heat-dead cosmos will constantly drop as the volume increases. It will asymptotically approach absolute zero.
Some others have noted that there are theories where energy and/or matter are spontaneously created in empty space. These can coexist with the heat death fate if the new energy is also evenly spread, which it probably would be in such a uniformly boring heat-dead universe. Still no way to create a new free energy gradient.
I find this an interesting fate because it's also reflected in some religions and philosophies, where everything becomes one at the end of time.
NASA definitely will not announce that they had proven the existence of "dark energy"; all they can really announce is that data they collected suggests an infinitely expanding universe. (This would not, btw, require dark energy, though an accelerating universe might; all it would require would be for the total matter and energy in the universe to be below a certain threshold level.)
I don't really know a whole lot about "dark energy" at this point... a few mentions here and there have given me a murky idea of it as similar to Einstein's cosmological constant, but nothing really definitive. Some recent evidence does, I believe, suggest an accelerating expansion which could lend credence to the theory... but I believe there have been alternative hypotheses advanced as well.
I am not a physicist, however, merely a freshman physics major. ;-) I know the NASA announcement isn't out yet so primary sources on this particular experiment are hard to come by, but can anyone suggest some background or current research on dark energy and the cosmological constant? My only real source so far has been Scientific American--that is to say, I've got no reliable sources. [grimace]
Much appreciated....
"Science is a way of trying not to fool yourself." -Richard Feynman
Seriously though, I think every cosmologist should be required to be an Electrical Engineer first. I should write a book, All the I needed to know in life I learned in Systems
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
Halton Arp, an award winning astronomer who used to be Edwin Hubble's assistant, has spent years documenting physically connected astronomical bodies with vastly different redshifts. That's simply impossible under the current theories. But they exist.
He's published several books on the subject including Seeing Red: Redshifts, Cosmology and Academic Science which presents considerable information that's been surpressed by astronomers whose theories have been threatened.
In Seeing Red, he also lays out an alternate, simplified theory, which is a _slight_ modification of the general theory of relativity that ends up predicting the real world observations without resorting to magic constants, curved space, "dark matter", and other kludges that the currently accepted theories need.
Here's some other info about it.
This concept of multiple universes makes absolutely no sense to me; doesn't, by definition, the universe mean "everything"? Hence, if multiple time/space continuums existed, they would just constitute different parts of the same universe?
:)
The best way to think about it is to imagine a balloon. Blow the balloon up. See the inner walls of it? That's the universe. You can place a pebble anywhere on those walls and roll it around, and it's pretty much trapped there.
Our universe (theoretically, anyway) is a special, 3-d balloon wall. Supposing the inner walls of the balloon were 3d, you could travel around in there, but never escape.
Now take hold of some of the balloon in one hand, so you've pinched off a sub-balloon. Give the pinch-point a small twist so it stays that way. A pebble rolling around on the inner surface of that pinched off bubble will never make it into the original balloon inner-space. They're connected, but it is impossible to get from one "universe" to the other. This is what is meant by the multiple universes sprouting off from each other theory. Singularities in space, etc, cause baby universes to "pinch off" from the one we know and love.
Disclaimer: IANAPP (I am not a particle physicist), but I've read a few books / magazines on the subject
That's how I think about it, anyway.
Even if we don't live in a closed, oscillating Universe, it's still possible that the Universe could "reboot" itself after the heat death. [Disclaimer: complete speculation follows. I am an astronomer, but by no means am I a cosmologist]
If we live in a non-oscillatory universe, then the Big Bang was not a "bounce" due to a preceeding Big Crunch. Rather, the Big Bang arose from a quantum fluctuation in the vast nothingness that was (or was not?) before. So, if the Universe of the very distant future has expanded to ~zero density and ~zero temperature, then it looks basically just like the pre-Big Bang vacuum. In that case, another Universe might very well pop up from another quantum fluctuation in the vacuum.
Hell, who knows? Maybe a sufficiently empty vacuum is extremely unstable to such Universe-spawning fluctuations, so they are pretty much certain to occur once the density and temperature get low enough. If so, there you go: we can have our heat death and still have Universal rebirth.
Liberal (adj.): Free from bigotry; open to progress; tolerant of others.
I sounds to me like all the facts are based on the red-shift seen in remote objects. Red-shift can also be caused by the decay of the speed of light. I don't know if it's true or anything, but at least it's interesting with regard to this matter - it's a theory that the speed of light in vacuum is not constant but is slowly decaying.
0x or or snor perron?!
We'd have to make some radical changes :) But at the time scales involved, I don't think a bit of engineering is going to be a problem. If any kind of life is still possible, at any speed, then a way will be found. (Remember that in a low-energy universe, slow and "fragile" processes are much more reliable than they are now. Waiting 10^9 years for a signal to pass from one neuron to another will not be a big problem.)
Well, I'm being pretty loose in my interpretations. I figure that's ok, though, because the one thing I definitely got from the University Buddhism classes I audited was that there's pretty much a variant for everyone.
;)
I have definitely seen end states described where everyone reaches Nirvana. I suspect this comes from the simple desire for a happy ending. It also more resembles endings in Christianity so that could be an influence too (but without the "hell" component, which is ongoing in most Buddhist conceptions anyway, whether you're a desire-ridden human or a hungry ghost). The alternative has infinite creation of new entities, but then you need a source for them, which kind of undoes the fact that it's an entirely reincarnation-based belief system (as with its roots in Hinduism).
It's all pretty metaphorical anyway; I also glossed over having multiple planes of existence in many or most Buddhist strains, of which this dying universe would only be one. But it beats watching TV.
A critique from a real Buddhist theologian would certainly be interesting.
But only if it's tomorrow's edition.
(I'm finding it hard to believe that I just made that reference.)
But then again, I could be wrong.
Yeh, but that is only how we look at things here on Earth, within enough of a margin of error, things at infinity, etc, do not matter to us for our purposes and applications. However, if you are looking at this in a purely classical physics matter and on the universal scale, then the momentum caused by the big bang, that is the movement of the universe now, can only continually be proppelled by further explosions. But the explosions have reactants and products, and pretty soon the reactants will run out (I would guess that the source of reactants is not infinite, just as any fuel that we know of is not infinite - whether it be for the Sun or for our cars). This means that further impulses will not occur to continually increase the momentum over infinite time. And, since gravity acts an infinitesmal force at even infinite distances, then in the end, gravity will always overcome the momentum, and the universe will have to crunch back in on itself.
And actually, if you look at it in this way, it sort of makes sense. The universe is just one big oscillating process, the origins of which we have no grasp of yet (through the sciences, the religions have explained this for a while now). But, we can imagine that if we just begin to look at the universe at some random point in time, it is either expanding or contracting. If expanding, a big bang has just occured, and the universe will continue to expand until the energies of expansion run out and the energies of contraction take over (ie Earth analogy: kinetic vs potential energies when throwing an object upwards). Then, when contraction energies take over, the universe will contract and collapse on itself, increasing temperatures, pressures, etc, and the result is another big bang that resets the universe to the original state that we observed it in: expansion. Lather. Rinse. Repeat.
This would lead us onto another big question though: where the heck did all this start from? Has the universe just always existed and the absence of a surrounding (in thermo terms) resulted in a process/cycle that has thermo properties that are entirely conservered (constant on the whole). But then, why would the universe exist in the first place? Perhaps our universe is just the surrounding for thermo processes in other dimensions? Who knows. It would be fun to get in a time machine and travel 100, 1000, 10000, 100000, then 1000000 years into the future and see what we have come up with and if we can explain anything any better (although I'm sure we'll have come up with many more details in the mean time, but will we really understand the origins of time and the universe then?).
Although the crunch effectively puts a maximum lifetime on any specific life, there is that slim theoretical possibility that another universe would arise from the crunch. As it is, the universe grows and cools to a homogeneous soup, and that's it. We can't reuse the universe, we have to get a brand-new one.
Basically, we can think of the universe as expanding linearly with distance (hubble's law). Now, there's a very special characteristic of this type of expansion: nobody can tell if they're the center. If there were a center, it would have no effect.
Think about the raisin bread - how can a raisin tell where the center is? Remember, they don't know anything about "absolute rest" either.
Visit RTB. There's no question about it, the universe was created with life, no, human life in mind.