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The Big Rip


Guest r3alchild
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Guest r3alchild

For a long time scientists believed that the universe was slowing down and would eventually collapse in on itself, this was called the big crunch. However now scientists have discovered that the universe is not slowing down but speeding up, this has been termed the big rip. The theory goes that there is this energy in the universe called dark energy and it is pushing the universe apart. Scientists don't know what dark energy is but they think it makes up 70% of the universe.

 

Here is more about it: http://www.universetoday.com/36929/big-rip/

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This is the right spot for it, chrisstavrous. I just didn't get to the article until now.

 

So, it looks like the universe will just freeze to death, instead of spacetime ripping itself apart.

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I am under the impression Dark Energy is no longer a theory, as it was recently proven to exist. I think Dark Matter has also been proven to exist. I'm not a scientist so I could be wrong about that.

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Guest r3alchild

 

I am under the impression Dark Energy is no longer a theory, as it was recently proven to exist. I think Dark Matter has also been proven to exist. I'm not a scientist so I could be wrong about that.

Yes I think dark matter is, but what I understood on the documentry about dark energy is they don't have any technology that can detect dark energy.

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Neither dark matter nor dark energy have been directly measured. We can only see their effects on the visible matter in the universe. We really only know what dark matter isn't (it's not black holes scattered throughout the universe, it's not neutrons, it's not neutrinos, etc.), but we're not certain about what it actually is.

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Okay, I'm not an expert, but I do have a sketchy idea of the history of the thing, so here goes.

Dark energy, known at the time as the cosmological constant, was originally a fudge factor Einstein introduced to General Relativity, in order to get his equations to describe a stable universe. In order for his equations to match what he thought the universe's rate of expansion should be (static, as in not expanding or contracting), there was an unaccounted for counterbalance, that would "expand" spacetime, or else everything should have long ago imploded under its own mass. This has obviously not happened, so he had to add the cosmological constant, to make his equations describe the universe as he thought it aught to be (for mostly aesthetic reasons, actually, a stable universe just looks better). He was not a happy camper about this, because it was quite literally pulled out of nothing, just to make the maths work out. We can observe the state of the universe, and whether space time itself is stable or moving, and that's just what Edwin Hubble did, a few years later. The thing is, he found a moving universe (!!). Einstein was even less happy about that at the time, but he eventually got over it.

So, basically, the Cosmological Constant was the theoretical prediction, and Dark Energy is what we observe. By 1998, we had confirmation that the Spacetime of the Universe doesn't just stay plumped-up, it actually expands and accelerates. Since Dark Energy is basically a repulsive force acting on space, and generated by "empty" space, itself, this means that as the universe's space time expands, there's more empty space, creating more dark energy, and it should accelerate. Weirdly, it's actually not possible to measure any "force" or "energy" directly, we can only see the effects it has on matter, which we can measure the states of. Example: find a jar full of gravity. Good luck with that. But you can see the effects of this force on you, as you stick to the Earth's surface.

The standard model explains forces as interactions between particles, which can be modelled with intricate mathematics and probabilities. So far, we've got particles whose jiggly little dances explain the electroweak force, and basically everything but gravity.

That's where the Higgs particle comes in (and why it's so flippin' elusive). The Higgs particle, like the Cosmological Constant, was predicted as a means of explaining the way gravity works - assuming it was "carried" by interactions of particles, like all the other forces we know of. So, to test this, we had to try to make one in an accelerator, and see if it existed, which would confirm the standard model. (Spoiler: it seems the Higgs, and therefore the Standard Model are confirmed, but with some interesting twists on the theme. It's when things don't quite work out like you'd expect in science that things get really interesting. Relativity is a great example (turns out there was no Ether, and light goes at the same speed no matter what. With weird consequences). Being proven wrong in science is actually a step toward more knowledge.)

 

See also the Great Debate (those swirly thingies are actually other galaxies, like our own, and the universe is HUGE.)

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Good post, ExCBooster. Einstein was later quoted as saying that the cosmological constant he put in his equations was his biggest mistake.

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