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Quantum Equation Suggests Universe Had No Beginning
cyberspittle writes: The universe may have existed forever, according to a new model that applies quantum correction terms to complement Einstein's theory of general relativity. The model may also account for dark matter and dark energy, resolving multiple problems at once. "In addition to not predicting a Big Bang singularity, the new model does not predict a "big crunch" singularity, either. In general relativity, one possible fate of the universe is that it starts to shrink until it collapses in on itself in a big crunch and becomes an infinitely dense point once again. ... In cosmological terms, the scientists explain that the quantum corrections can be thought of as a cosmological constant term (without the need for dark energy) and a radiation term. These terms keep the universe at a finite size, and therefore give it an infinite age. The terms also make predictions that agree closely with current observations of the cosmological constant and density of the universe."
Equations and theories that not only explain current observations but bundle up and deal with things our other theories say we should observe that we don't are attractive from a neatness standpoint. I'm skeptical when they make exotic and complex predictions which we haven't seen any evidence of yet, but when they tie up all the loose ends without creating more I usually take that as a sign there's something fundamentally right about that path. Only time and accumulated evidence will add certainty to it, but I like the ideas in this one.
And as far as a universe with no beginning or end is concerned, what's the problem? I was dealing with infinite open shapes (lines, planes) in grade school, unending closed shapes are trivial (a circle, a sphere), and if you assume our universe is a 4-dimensional "slice" of an n-dimensional space it's not that hard to construct an arrangement where you can travel forever in any "direction" (since the time axis counts as a direction here) inside our universe without either encountering an edge or returning to your starting point. The math's brain-bending when you start, but it's like differential equations: migraine-inducing and you hate it with the burning fire of a thousand suns right up until they describe the General Method, at which point you blink and go "Oh. That's easy. Why didn't you mention this in the FIRST PLACE?!
OK, these guys are probably far smarter than I'll ever be, but... the universe clearly isn't staying at a finite size, and playing the universe's expansion in reverse would imply that it started at a single point. How do they account for this? I even went as far as to read the article, but it wasn't mentioned.
Are they saying that the universe fluctuates between a not-quite-a-singularity tiny point of density and a not-quite-eternally-infinite empty void, or that it simply was a not-quite-a-singularity tiny point of density for an infinite time before it expanded?
It's interesting, but I'm curious as to whether the model shows a universe developing with the features we observe. The density of the universe is one thing, the general structure of it is another. There seems to have been a lot of thinking around how the universe was shaped by the big bang including all sorts of models and simulations. It'll be interesting to understand if this new model also fits.
and that involves a certain plant, a yard of gummed-edge pressed wood pulp and a bucket of munchies.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
...it's turtles, all the way down.
Table-ized A.I.
One of the many, big, unanswered questions concerning the origin of the universe is - where did the energy come from? Conservation of energy - the assumption that energy cannot be either destroyed or created - is a fundamental axiom in physics, which goes against the idea that there was a point in time before which the universe didn't exist, but after, it did. Unless, of course, one can conceive of a negative energy of equal size having been created at that same moment.
A naive consideration would say that if a mass, M, is created, then there must have an 'anti-mass', -M, as well; using Newton's equations, we would expect M and -M to repulse each other, while M would attract M and -M would attract -M (yes, doesn't make sense at stated, but follow my thought here, OK?) And, if one were to ramble on along those lines anyway, it seems tempting to look at the equations for how electric charges interact and think of electric charge as a kind of imaginary (as in complex numbers) mass. No doubt better people than I have already spotted this and worked out why it doesn't make sense, but I haven't seen their work yet.
Comcast Theory
Table-ized A.I.
All of these type of models about the universe have elegant math behind them.
But until they can any observable predictions which can be measured and possibly falsifiable, then we are really dealing with pure math and philosophy and not physics.
One can construct countless mathematical models which fit known observations, but very few make new falsifiable observable predictions.
This is my gripe with something like String/M-Theory, which has not made any legitimate predictions, and fails at stuff like monopoles which not been observed.
Suppose the Universe is filled by a Bose-Einstein condensate of gravitons with mass, and that the amplitude of the condensate's wavefunction spans the entire universe.
Turns out that when you derive the FRW equations from this, doing so inserts a cosmological-constant lookalike into the equation for a''
So plug the size of the Universe into the Yukawa equation and a graviton mass of 10^-32eV pops out. Plug this into the assumption that the wavefunction is a Gaussian the size of the universe (which makes d'Alembertian proportional to the wavefunction and gives you that nice constant) and you get a cosmological constant that's plausibly near to what we observe.
Inserting the universe-condensate also creates a second correction term which prevents the FRW scale factor from blowing up or collapsing either in the past or the future, which makes that nasty big bang singularity go away.
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It's worth noting that they invoke Bohmian quantum mechanics, which will immediately sketch out a lot of quantum folks...
What bugs me is that the massive graviton blows up the mass hierarchy problem. It's hard enough to come up with a non-contrived way to have particles whose measured mass ranges from 1eV to 170GeV, but to extend it by 30 orders of magnitude on the light side is just mean.
too bad we can't verify them. Especially since the thrown most of the assumed ones out of their model. It's nevertheless an interesting approach in describing the universe if you take the time to read about it. Who knows, maybe the existing models were over-constrained and it might not be bad to give them a fresh look.
The truth probably lays somewhere in between.
A few years ago, a colleague proposed the idea that North-European population are tall because of an adaptation to the colder climate.
He could prove his theory but only for a perfectly spherical viking.
You know, what I've often asked myself is, "What was there before the Big Bang?"
Thats a bit like asking what is south of the south pole.
Two experimentally physicists, with one shouting: "Oh God, shut if off! Shut it off!"
But seriously, as AC has posted, the question is meaningless if time "started" at the point of the Big Bang. Hard to get your head around maybe. I know my mother has problems with it, but she also poses strange questions like "why aren't apes having human babies now." It's like a hundred years of science has just slipped past her.
Anything we know, have known and are able to know takes place after the big bang, thus asking what came before it is a question we cannot really answer.
But there could have been something, right? What was there is just more of a philosophical than a scientific question.
Obvious question, if the universe is infinitely old why do we still have hydrogen left for fusion?
In music, there is something called a Shepard tone, which is a series of skillfully combined harmonics that, when listened to as a loop, appears to be constantly ascending.
Perhaps the "expanding universe" is something like that.
- Mike
Thats a bit like asking what is south of the south pole.
Maybe. But the current model could be wrong.
I suppose that radioactive materials were put here by Satan to trick us. After all, with a perpetual universe we would have reached the half life of nuclear materials over and over again and we would have no radioactive materials at all. Oops!
Certainly I agree with you, there is a lot we don't know. The trouble is, at the moment, in order to speculate on this, we are leaving science and entering philosophy. Science does not have an answer for us here, and maybe never will. We have some math, but nothing that really means anything to us.
I would say that these questions cannot be objectively answered - there is no way to measure what happened 'before' since there is no frame of reference that would be meaningful to us and allow us to understand what 'happens' outside our little bubble of physics and space/time. How do we measure outside of space and time? What are we measuring for that matter? What does 'before', or 'cause' or 'effect' mean in such a reality?
As a self professed religious person, I believe there are subjective and unprovable answers. Others disagree and are happier with the questions. In either case it seems wise to not give up on looking.
I have determined that my sig is indeterminate.
General relativity does require a beginning to the universe. Einstein realized that a universe dominated by an attractive force had to be either shrinking or expanding. He didn't think that was realistic, so he added the cosmological constant to balance the attraction of gravity and get a static universe. That was in 1907-1915. People started doing galactic redshift surveys (with a handful of close galaxies) around 1912, but it wasn't until the late 1920s that it started to be accepted that the universe was indeed expanding.
It turns out that even with a cosmological constant, GR doesn't admit a static universe.
Philosophically we are faced with two explanations, neither of which we can comprehend in a physical sense, ie: infinity or nothing. Personally I find nothing a lot harder to imagine than infinity, even though I clearly did not exist before I was born.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
The question is meaningless. In fact, it's meaningless from a physics point of view and also meaningless from a theological point of view. It was asked often and a good answer by Saint Augustine ("What God did before the creating of the Universe?") was (roughly) "The question is meaningless since time is a attribute of the universe and God exists outside of it." The equivalent answer applies to the Big Bang.
English is not my first language. Corrections and suggestions are welcome.
You know, what I've often asked myself is, "What was there before the Big Bang?"
Nothing. As accepted, currently, time began with the Big Bang, so there was no before the Big Bang.
No, definitely meaningless. Time itself began with the Big Bang. The instant of the Big Bang is t=0. There is no t = -1. If there could be, then there would be time, which would pass from that point leading up to the moment of the Big Bang. But time began with the Big Bang.
But, our language and consciousness are so dependent on the concept of time that we lack the language to describe a state of being without it. Which is why we erroneously say things like "before the Big Bang," but it's a meaningless statement, because "before" implies an ordering of time, and time only began with the Big Bang. I had to be careful there to not say "there was no time before the Big Bang," because "was" also implies time. That time ticked along counting down (or up) to the Big Bang, then everything blew up. See there? I just gave a time-ordered sequence of events. But time-ordered sequences of events are only possible after t=0.
We don't have a state-run media we have a media-run state.
Photon. Time is nonexistent.
Or $TIMELESS_DEITY. Time exists, but has about as much meaning as the time index of a video. It makes more sense to watch everything in proper order, but you're free to watch the thing in reverse if you like.
But time-ordered sequences of events are only possible after t=0.
Imagine you're a CPU and your perception of time is in clock cycles. Would you be able to give an ordered sequence of events of all the things that happen before your clock generator starts, e.g. voltage ramp-ups, etc?
You know a "religionist" came up with the Big Bang Theory right?
Well, let's say the question is premature. Before you can ask it, you have to determine whether the question itself is based on false assumptions. This kind of question is tricky because questions you *can* ask meaningfully have the same syntax as questions which are meaningless.
For example, you can ask "What is colder than 0 degrees C?", but you can't ask "What is colder than 0 degrees K?". One question is meaningful and the other is not.
So asking "What happened before the Big Bang?", entails two assumptions, namely (1) the Big Bang happened and (2) the scientific consensus on the Big Bang is fundamentally flawed. If the scientific consensus is correct, then it's like asking, "What's colder than 0 degrees K?" or "What's north of the North Pole?"
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
At least credit the source Hawking (or earlier).
But for every equation or citation in my post, I lose half my audience.
Einstein - Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.
Temperature is a measure of molecular motion. 0 K is the point at which molecular motion stops. So, while you can make comprehensible sentences around the idea of -100K you can't make meaningful sentences about a state in which there is less than 0 molecular motion. The only way that you can make sense of the sentence is by ignoring the meaning of terms within the sentence.
--
JimFive
Please stop using the word theory when you mean hypothesis.