Multiverse

[mickoking]

The one question I have always had a problem with is, What happened before the big bang? To me there must have been a prior event that percipitated the BB, every thing has a cause and effect.

[cometcatcher (Kevin)]

Big crunch? Crunch/bang/crunch/bang?

[cometcatcher (Kevin)]

Originally Posted by Rodstar

So long as we are all honest about the fact that we conduct our lives relying upon a lot of beliefs which are not scientifically verifiable.

Theories often start with beliefs. Not all theories are testable due to technology limitations at a given time. But in a future time they may be.

If we limit ourselves to what is known and testable and there are no beliefs or theories then how can we advance in knowledge?

[jjjnettie (Jeanette)]

Big Bang.
Maybe that is what happens after a Black Hole has gotten so big that it draws in all matter, collapses under it's own weight, then explodes the whole lot out again.
Not so much a Big Bang, as a Big Belch.

[astrofiend]

The one question I have always had a problem with is, What happened before the big bang? To me there must have been a prior event that percipitated the BB, every thing has a cause and effect.
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Ahh... Here it starts to really get interesting. Physics at the point of the Big Bang is foreign to us. General Revlativity implies that both space and time came into existence at the moment of the Big Bang, and that previous to that the Universe was a singularity. Hence you cannot talk about a 'before' because time literally started with this event. Quantum principles can help reintroduce causality in some sense, and physicists talk seriously about 'quantum fluctuations' initiating the event, though time itself did not exist as we know it at this point.

The problem with it all is General Rel and Quantum Mech. fail us at this point as they are mutually incompatible. They are not accurate descriptions of the universe in these extreme conditions. A new description is necessary, which is why the search is on for a theory of Quantum Gravity, of which GR and QM will be limiting cases. There are a multitude of candidates for QG.

Also, we have a fair idea of the characteristics of the universe during the BB event, such as what temperatures and pressures were reached, what must have happened afterwards and whatnot, but very little idea of what the BB event actually was. Hawking proposed that it all started with a singularity, but other ideas include collisions of higher dimensional spaces (branes), collapse/rebound theories and so forth!

The basic BB theory has had spectacular successes, but at the same time there are many things that it either cannot explain or are in outright contradiction of it. Also, current theories dealing with things such as dark matter and dark energy are essentially just patch jobs, showing that we still have only the vaguest idea of what is really going on.

Exciting times lie ahead - I love Science!

[mickoking]

Originally Posted by astrofiend

Ahh... Here it starts to really get interesting. Physics at the point of the Big Bang is foreign to us. General Revlativity implies that both space and time came into existence at the moment of the Big Bang, and that previous to that the Universe was a singularity. Hence you cannot talk about a 'before' because time literally started with this event. Quantum principles can help reintroduce causality in some sense, and physicists talk seriously about 'quantum fluctuations' initiating the event, though time itself did not exist as we know it at this point.

The problem with it all is General Rel and Quantum Mech. fail us at this point as they are mutually incompatible. They are not accurate descriptions of the universe in these extreme conditions. A new description is necessary, which is why the search is on for a theory of Quantum Gravity, of which GR and QM will be limiting cases. There are a multitude of candidates for QG.

Also, we have a fair idea of the characteristics of the universe during the BB event, such as what temperatures and pressures were reached, what must have happened afterwards and whatnot, but very little idea of what the BB event actually was. Hawking proposed that it all started with a singularity, but other ideas include collisions of higher dimensional spaces (branes), collapse/rebound theories and so forth!

The basic BB theory has had spectacular successes, but at the same time there are many things that it either cannot explain or are in outright contradiction of it. Also, current theories dealing with things such as dark matter and dark energy are essentially just patch jobs, showing that we still have only the vaguest idea of what is really going on.

Exciting times lie ahead - I love Science!

It does look like we live in a golden age of cosmology. The universe (or multiverse ) is getting more bizarre and fascinating by the year.

[robagar]

Originally Posted by mickoking

The sun centred solar system was once a hypothasis too. But to some it made sense and eventualy Kepler and Galileo proved that indeed the earth and other planets orbit the sun. Sometimes, some of us go out on a limb, that to me make's science exciting and a little reckless

yes, likewise superstring theory today. Been purely theoretical for ages, but finally possibly becoming testable at least indirectly. The most intriguing one for me is seeing if gravity square law breaks down at really small scales, indicating the existence of >3 space dimensions. (string theory predicts 6 or 7 extra, curled up really small)

[barees63]

FWIW, I just finished a really good book about this very subject: "Parallel Worlds: A Journey Through Creation, Higher Dimensions, and the Future of the Cosmos" by Michio Kaku.. well worth a read if you're interested in current cosmology (it's also at fictionwise for anyone reading on a PDA)..

[robagar]

Brian Greene's The Fabric of the Cosmos is also a good 'un

[glenc (Glen)]

http://www.skyandtelescope.com/news/28528759.html
We usually think of the universe as being “everything there is.” But many astronomers and physicists now suspect that the universe we observe is just a small part of an unbelievably larger and richer cosmic structure, often called the “multiverse.” This mind-bending notion – that our universe may be just one of many, perhaps an infinite number, of real, physical universes – was front and center at a three-day conference entitled "A Debate in Cosmology — The Multiverse," held at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, earlier this month...

[AlexN]

So... Do we have opinions on if the many "universes" within the "multiverse" occur in the same space/time except somewhat out of phase.... Provided that gravity is a multiversal constant (let us assume for a minute) This theory (brewed up in my own mind over the past couple of days thinking about it, so excuse its crudeness.) could help account for why gravity is the weakest force in our universe... Lets say for example, you have the multiverse containing several universes all sharing the multiverses gravity, obviously we would only be getting a small share of that gravity hence its weakness...

Its all fun to think about etc, but until it can even be studied, let alone be found true or untrue, I think the matter is best left alone...

Humans do have a tendancy to work things like this out when they need to... We figured out the world was round when our development came to a point where international trade was viable.... Or something like that...


WARNING : Everything contained in this post was pure opinion, and thinking out loud. Not intended to start debates, nor was it intended to be taken fairly seriously... (Read: Dont shoot me if I sound Insane )