big bang "pillars" of proof

It's not even clear that we can do experiments that will definitively tell us what the early universe was like. Inflation answers a lot of questions, and gives testable predictions, which are confirmed. If inflation also implies that there is a multiverse and not a universe, it is an implication of the theory. To argue against it definitively you'd have to come up with a new theory.

What type of anomalies are you referring to? Surely not the axial vector anomaly?

If one is led to the existence of a multiverse by a string of consistency checks, we have no choice but to accept it, unless another theory comes along which better explains the data.

 

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is it wise to accept a theory as fact because its the best we can come up with and then having to change it when a new discovery is made?


also i think the longer we hold onto a theory the harder it is to break away from it.

peace.

 

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Yes. This is how science is done.

 

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Hey good now we can see how u look, Nice Avatar

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I agree with u. Actually i have changed a lot after joining this forum and sometimes i too become abusive towards others. Clearly these people have a negative effect on us due to relaxed attitude of moderators on personal attacks.

 

Oh, you are so better than me 'cos you just got here! You haven't spent much time here, which makes you a better person! NOT!

And you have much better use for your time, which is why you wrote such a long ad-hom and dodged the question!

More ad-hom diversion. Post something of substance.

 

Anything consistent that points towards there being a force in nature that we cannot explain without introducing external factors, really. Inflation could be that, maybe whatever caused the anisotropy, who knows?

I'm still trying to get my head around how this could could work, how smaller universes could interact and affect each other early on, and then effectively become hidden as inflation pushes them apart. I'm still tripping up on that boundary though. See if you can come up with a good analogy there, it might help.

 

Well, I've never worked through the details, but the picture I have is like a piece of styrofoam. If you look at the styrofoam, it's made of a bunch of little pockets. Imagine the early universe being made of a bunch of little volumes, all about the Planck size (10^-33 cm on a side, or something like that). Now before inflation, those little bubbles are slowly growing. Immediately before inflation, they're about the size of an orange, or so. AFTER inflation, they're much bigger, like the size of the solar system or something. So the universe began as a bunch of little Planck sized bubbles, but these bubbles have expanded, so that the end product is a bunch of really big bubbles, that can't talk to each other.

The bubbles can't interract with each other, and the only way we could detect their existence is through gravitational waves, or something. I think Oli said something about the laws of physics being different in the other bubbles---this is very plausible, because we don't understand the higgs particle very well.

As for the boundaries, I don't know. What I can say is that, even travelling at the speed of light, we would never encounter a boundary. I think the phrase to google is "domain wall", but again, I'm not sure.

Again, this is the picture that I have in my head, and someone can feel free to correct me---I've never worked through the calculations, and I am not an expert. If I have time, I will talk to some cosmologists (who live down the hall) and maybe they can correct my picture.

 

Hi Ben, I don't like the bubble analogymuch, because it's spacial. I prefer the idea that it could be possible for different universes to exist in the same space, but their interaction is limited because they have maybe just one common dimension. They overlap but do not interact much, some weak force manages to perturb the matter of the other expression.

But anyway, if they did occupy the same space, and did kind of interact at some level, they would still be part of the 'Universe', we'd just know that parts of it were intangible.

 

i once saw a video (on youtube) of a car which accelerated to 2,147,483,647 mph.

 

I don't try to imagine universes existing in the same space. Why would they need to? We have absolutely no reason to assume they would. Why would they need a common dimension at all? Well maybe because if they didn't, the other universe would not effect us on any level whatsoever right? Well not if that dimension was invisible to us in every visible and observable way.

I try picturing universes expanding outward on a 2-dimensional surface (each surface containing all the data for that universe). Maybe this surface is only a Planck length in thickness. Perhaps something not observable, for instance, dark energy may pass unimpeded from one sheet to the next. While we can not see it directly, we can see it's effects. The universe seems too uniform to have happened naturally and it's now looking likely that dark energy had a large role to play in this uniformity. We have to consider the possibility that it may be impossible to establish a unified testable theory since our minds cannot abstract the concept of additional dimensions without a frame of reference. Space is not empty. It only APPEARS empty. I can't ask you to conjure up an image of something you haven't already abstracted from something you've seen before. That would be like asking a neanderthal to imagine an Airbus A380. Since all our thoughts, instrumentation, etc. exist within this small 5% of visible matter in the Universe (the rest being dark or invisible) how could we possibly test something else? It would have to have a measurable effect on our 1/20th of the universe. And it's fairly well accepted that something is. So I do agree with phlog in that unification is necessary if for no other reason than to be able to say that for a fact, this or that is NOT coming from within our universe. I'm at least 90% certain that anything we accomplish towards that particular end will be purely by accident.

 

Well, no matter how you cut it, gravity has to live in all of the dimensions, whether you have four or eleven or N. So in your picture, the universes would interact gravitationally, so we could detect them.

 

See my previous comment to Phlog. The point is, one has to be careful adding matter to other dimensions---it is not an easy thing to do.

But we can observe dark energy by its effects on the space between galaxies. And it's not even clear to me that dark energy can "flow". It may be a fundamental property of the vacuum, in which case it is present everywhere at all times.

If you believe in inflation, you have no problems with this uniformity.

This is a metaphysical statement, at best. There are good reasons to believe that we can't understand our universe completely, I completely agree. But you must also accept that it is completely plausible that one equation, with apropriate boundary conditions, will specify the life of the universe.

"Not visible" means that it interracts with matter only through gravitational interactions. It may be that the dark matter is made of the lightest supersymmetric particle, or a particle of odd parity that can't decay. Then we may know very well the properties of such matter when the LHC turns on. The effect will be missing energy in a detector---that is, a particle will decay into a bunch of stuff we see, and one thing that we don't. The thing we don't see is dark matter.

So would you give me 10-1 odds that the next major advancement in physics will come from outside academia? Because I'll take those odds

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I don't know what you mean by accident... Much scientific discovery is accomplished by accident, but one cannot determine, a priori, which discoveries will come in this way.

 

double post

 

To be cont....

 

See here:

http://www.sciforums.com/showthread.php?t=66736

 

There is no reason for this. Are you basing this statement on any calculations?

What do you mean "degrees of uniformity"?

Then we are arguing on two different levels.

It's fantasitcally consistent with our existing models. And if there is a unified theory, it's pretty clear that it should incorporate supersymmetry in some fashion.

This is unlikey.

It seems you are making braod general statements, which is ok. But you should realize that I have done some (not all!!!) of these calculations, and am speaking from that perspective.

 

If that is the case (and it's not obvious to me, because I don't understand gravity, but then, who does) it could be what is fuelling inflation perhaps?

Until we understand the mechanism behind gravity, I don't quite see why it would be Universal, where charge, electromagnetic forces, strong or weak nuclear forces wouldn't be?

 

Well, dark energy is having the opposite effect of gravity. Gravity doesn't cause things to repel.

[/QUOTE]Until we understand the mechanism behind gravity, I don't quite see why it would be Universal, where charge, electromagnetic forces, strong or weak nuclear forces wouldn't be?[/QUOTE]

Higher dimensional models are ostensibly string inspired. In string theory, gravity is a closed string, while matter is an open string. The ends of open strings have to be stuck to branes---so if you imagine our universe confined to a three brane, then the matter is confined to three dimensions. Gravity, as an open string, is free to live in all of the dimensions.

If you don't like string theory, then a more general argument is that gravity seems to be universal in the sense that the energies which it becomes important are very very large, which correspond to immediately after the universe began. The other forces weren't around untill much later. So anything that was happening in the early universe had to interact through gravity.

 

Simple answer: nobody

Our model of gravity needs revisited. Heavily. We already know it breaks down on the smallest scales but now we observe it breaking down on larger scales? To call it "fantastically" consistent. Well, that's just... Are you doing your calculations on a chalkboard made of baryonic matter? If you proceed forth based on the theory of expansion, then why did galaxies and clusters form at all? Why is the universe accelerating? I believe the universe has some degree of uniformity but only when viewed from a macroscopic scale. Skip past that and you have to question what keeps galaxies together at all. Certainly not gravity. The Doppler Shifts reveals that stars are moving at rotational velocities that should rip galaxies apart. And there are reasons the universe should be slowing down. One big one: your friend there... Gravity. Gravity should eventually reign in the aging universe and radiation measurements show that it actually started to at one point but then began accelerating again. All of this is based on the theory that there was a bang at all. You may not believe there was. I'm glad you have done all the calculations you have and I did make some broad strokes there but this is a time for theorists. We need new theories. If you have worked the chalkboard as much as you say, then you have to realize by now "It just don't add up!"