Why haven't we had another big bang?

[haitch]

Yes it's a PITA that we can't examine the inside of a black hole - we might find some of those elusive other dimensions.

I once thought the solar system was fairly big until I looked at an atom...

If a proton was the size of a peppercorn the electrons in its shell would be "orbiting" something like a couple of miles away.

Essentially we are made of just about nothing held together/apart by energy. Maybe we are just a holographic projection on the event horizon of the black hole that forms our universe?

[Brainstorm]

Maybe there's been many more. How would we know?

If the next nearest BB was so far away from our known universe, making our universe look like a mere pin head in the far reaches of space, we would never even be aware of it.

Some scientists say the big bang was not big and not even audible.

[RobSay]

Do we know that there were previous big bangs before the one that spawned our existence?

The absolute answer for other Big Bangs is I think 'No'. However there is some research that came out last year that puports to show evidence of pre-BB events in the WMAP data.

The abstract is here: [1011.3706] Concentric circles in WMAP data may provide evidence of violent pre-Big-Bang activity

and was reported in more accessible press:

No evidence of time before Big Bang : Nature News

BBC News - Cosmos may show echoes of events before Big Bang

R

[mikeknowle]

The "big bang" theory doesn't tell us what caused the big bang, it just says that conditions in earlier times were different and then quantifies that difference.

And although we are almost there, we don't yet know the exact conditions at the initial moment the (current) universe was created. And therefore we don't know anything about what happened before (if there is such a thing/time) that. Or what caused it, and why, or how.

So many questions.....so little time....

[Karlos]

I personally think the universe will repeat itself (But baring in mind we are approxing living in the 13.5 billion year old universe and theres very little sign of things calming down yet, its going to be a long time), like most things we see in the universe it is never used but changed (a cycle if you will of transformation), like energy or information conservation. The universe will be cool and calm just like it started and ours will end (We think, according to the 2nd law of thermodynamics) this dormant cold place will eventually see a slight change which will trigger a big bang almost in the butterfly effect fashion.

[ollypenrice]

In the expanding balloon analogy you absolutely MUST remove from your mind all that is not the SURFACE of the balloon. Only thesurface appears in the analogy. Inside and outside the balloon do not exist, in the analogy.

With regard to your question, one cosmologist, at least, thinks it possible that we have had not one but many.

This hypothesis was produced by the great Lee Smolin. Unhappy with the fine tuning of the numbers needed to make the big bang produce stars and so produce us, he wanted to create a model in which star forming universes were likely rather than overwhlming unlikely as in most others.

So he came up with a Darwinian model in which Universes reproduce when high mass stars implode to form black holes. Perhaps these black holes trigger new universes with an imperfect 'memory' of their parents, so they too produce stars. The better the offspring universes are at producing stars, the more they reproduce, so star forming feeds back into universe forming and becomes probable rather than improbable.

It is more hypothesis than theory but worth a think all the same.

As for 'where are they?' - well, by definition they are elsewhere. They do not occupy our space dimension or our time dimension, they have their own.

For more, see The Life of the Cosmos, Lee Smolin.

Olly

[meteoriot]

What if the universe is just part of a much larger structure.

From quarks to sub atomic particles to atoms to gas to dust to asteroids and comets to stars and planets to galaxies/black holes to the cosmic web etc

The former always seems to be a tiny 'particle' of a much bigger structure so why should this stop beyond the limits of what we can possibly observe.

The smaller the object the faster they happen and the larger the longer it takes but this is all based on time and size from our perspective. It's difficult to for me to imagine 13.7 billion years but it's probably just a micro second in relation to what is beyond.

[Gilps]

I'm pleased that people are still contributing to this thread. I've enjoyed reading the replies and theyv'e certainy given me a lot to think about. Thank you all for your contributions.

[David Torp]

I appear to be a late comer to this thread, but I thought I'd add my two cents worth. We believe we can see about 13 billion light years, this is our ‘observable’ universe and this distance is taken to be how far we believe our universe has expanded since the (last) local big bang. This does not mean this is the extent of the actual universe. We will never be 100% sure what is beyond this ‘observable horizon’ of 13 billion light years. I believe what lies beyond may be the remnant of previous or even parallel universes.

We believe our universe’s expansion is accelerating. There may be an infinite amount of mater beyond our ‘observable’ universe drawing via gravity our observable universe out driving it’s accelerating expansion. Much of this unobservable mater may already be dark and be trillions of years old. If the actual universe is infinitely big and therefore infinitely bigger than what we can only observe, then we may even exist in one of an infinite number of current parallel universes with life. I am not supposing that these parallel universes are on some sort of parallel plane of existence, I am merely suggesting they are further than 13 billion years away and therefore we will never be able to see them.

In a trillion years when our current ‘observable’ universe has drifted and devolved into empty dark space maybe another big bang generated universe will pass through this way. Anyone born into that universe may also wonder how the universe came to be, not knowing others had been before asking the same questions.

[ollypenrice]

David, I'm not sure that all of the above is correct. The 'observable universe' is the name given to that part of the universe whose light can, in principle, one day reach us because it lies within that distance beyond which the Hubble Flow exceeds the speed of light. That should not be confused with the age of the universe, currently estimated to be 13.7 billion years. Light which has been in flight for 13.7 billion years set out from a point which is far, far more than 13.7 billion lightyears years away now because, during the flight, the starting point has been receeding due to the Hubble Flow.

Olly

[David Torp]

Olly,

It is refreshing to receive what I see as an intelligent reply to a post. I'll accept my error on the age issue, but I'm not sure I can agree with the clarification on the definition of observable universe. I will always argue it's boundary with respect to earth at any point in time should be what can physically be observed from our vantage point.

Regardless of the numbers discussed and the definition issue, which I’m probably also wrong on, the key point of my post was an attempt to rationalise some of the formal observations made. My thoughts were that the chances of all the mater and energy in our observable universe seemingly spontaneously materialising out of nothing would be for arguments sake be around a gazillion to one. I’m not sure that figure is actually a real number, but anyway, maybe every gazillion years in an infinite universe a big bang happens around these parts based on random chance. The last time it happened around here previously would be subsequently so long ago nothing is left of the previous universe, except maybe its gravitational pull that is dragging our universe after it; as it too is dragged by its predecessor in a never ending expansion. Even some of this dark mater reported in our region is just debris from past remnants.

[themos]

spontaneously materialising out of nothing

Don't underestimate "nothing". The quantum vacuum is a surprisingly rich environment.

[JulianO]

There are some nice models of the universe that work in a cyclic way, with two branes bumping together to kick the whole thing off.

Dark matter however is not a remnant, its a vital component. Its very hard to form galaxies without it.

[ollypenrice]

I'd recommend 'The Book Of Nothing' by John D Barrow, a man who knows his onions.

As used in scientific parlance 'the observable universe' is absolutely not the universe that our technology allows us to see. It is far far bigger and my definition above is the one in common use.

Strange place, the Universe. Local experience can easily lead the mind astray. But what do I know, I'm just a jobbing astronomical photographer!

Olly

[Ags]

The reason there has not been another big bang is that it took 13.5 billion years to build another Large Hadron Collider, and we have not run it at full energy yet... :-)

[Capricorn]

Why haven't we had another big bang?

Because 13.5 billion years, give or take a bit, is a very, very short time on the scale that the universe operates.

[themos]

Why haven't we had another big bang?

Who says we haven't?

[ollypenrice]

Who says we haven't?

Awe, don't stop there!!!

Olly

[JulianO]

There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened.

Can't beat Douglas Adams

[foundaplanet]

I think the big bang is constantly happening along with everything else that has ever happened and possibly can happen. I think this simply because I reckon time is a condition of being alive and is relative to experience.

The older you get the faster time goes, not through fear of getting older but because of the amount of time you have been here. Five years to a ten year old effectively being the same length of time as twenty five years to a fifty year old. So for me if you was 14 billion years old, 7 billion years would pass as quickly to you as five years to a ten year old, it is this relative. I doubt that time is relevant to the universe, only humans (life). It could have been here for 50 billion years or 1000 billion it doesn't matter.

If light is the optimum speed within the universe where everything comes to a standstill, lights travel time must be immediate. If this is so then surely time is equal to the speed of light and everything must be happening all at once with all plausible possibilities.

The big bang is probably the point at which one random particle synthesizes itself.

[Skybrowser]

There are some nice models of the universe that work in a cyclic way, with two branes bumping together to kick the whole thing off.

Dark matter however is not a remnant, its a vital component. Its very hard to form galaxies without it.

I didn't even think they've proved Dark Matter to exist yet? Maybe I'm wrong. if it hasn't been proven and remains theoretical, how can a theory of galaxies being very hard to form without it? That's a theory on a theory and doesn't work in my eyes. Hands held up if it dark matter has been proven to exist.

On the observable universe question, 13 billion light years is a hell of a long way away and we're perhaps close to the edge of observable-ness..,,,.

All of this thread is really interesting to me, but whenever I hear astro physicists say the magic words "for reasons we don't know about yet" (B Cox says that a lot), I switch off as the rest of the sentence is not theory but pure conjecture. Nevertheless, I am fascinated by how many different theories there are.

Earlier on in this thread, the new one (to me) about the Big Bang happening everywhere all at once goes against the previous grain of galaxies - and consequently the Universe moving away and expanding outwards at rapid speed.

The truth is out there... and I suspect we are getting very close to it. Really interesting stuff.

[themos]

I didn't even think they've proved Dark Matter to exist yet?

No, and they never will because nothing ever gets proven in that way. All it takes is for the same model of dark matter to be useful in lots of different situations (such as forming galaxies) and people will continue to use it. They will stop when either some inescapable prediction of dark matter theory turns out not to be the case or a better theory emerges that explains more phenomena with fewer assumptions.

if it hasn't been proven and remains theoretical, how can a theory of galaxies being very hard to form without it?

All it means is that if you don't include some dark matter and you work out the implications of all the other theories we know about, galaxies take much longer to form than is actually the case. It means that All-our-theories-minus-dark-matter is wrong.

whenever I hear astro physicists say the magic words "for reasons we don't know about yet" (B Cox says that a lot), I switch off as the rest of the sentence is not theory but pure conjecture

Can you give an example? I can imagine people saying this about some observed phenomenon which is not conjecture at all.

[themos]

Earlier on in this thread, the new one (to me) about the Big Bang happening everywhere all at once goes against the previous grain of galaxies - and consequently the Universe moving away and expanding outwards at rapid speed.

Mental pictures only take you so far. That's why cosmologists communicate with mathematical formulae and not just diagrams.

[Skybrowser]

Thanks Themos - that's easy to follow. On the "for reasons we don't yet understand" if you watch any of Brian Cox's shows when he's explaining stuff, origin of stars, black holes, the universe etc. he says that. I've heard similar stuff from other people in the know too. Can't give you a specific example at 10.30pm on a cold and bleak March night, but the term was used in the sense of trying to explain something to the viewer.

It's said in such a way that you're focus is turned away from that statement and more towards the next bit - that's when theory becomes conjecture - or pure guess work.

I know this is guesswork from a highly informed source, but the sceptic in me actually hears the "reasons we don't yet understand" line and thinks, this is hokum - you don't actually know but you're continuing the thread of thought which conveys that you actually do.

Sorry if that sounds negative - absoloutely not my intention. It's just that there have been so many genuine discoveries, in particular over the last few years that I find the thought processes of some individuals who purport themselves and get acknowledged as experts subsequently making statements that seem a bit misleading. I mean, that they are not stating fact, but they seem, or rather are portraying what they to be fact.

[JulianO]

I didn't even think they've proved Dark Matter to exist yet? Maybe I'm wrong. if it hasn't been proven and remains theoretical, how can a theory of galaxies being very hard to form without it? That's a theory on a theory and doesn't work in my eyes. Hands held up if it dark matter has been proven to exist.

Well - it depends on what you require as proof. Can you go down to the store and buy a bottle of dark matter - no - because we're not sure what it is.

Would our Milky Way or the Andromeda galaxy hang together without dark matter? No it wouldn't. The outside stars are moving too fast for the amount of visible matter to be held onto. They should be flying off at a considerable speed, but they're not.

So - you postulate extra "dark" matter which if it formed a halo around the galaxies would make everything right with what we observe, and also fix a number of other awkward issues (like missing mass in gravitational lenses, and the weight of galaxy clusters being off by considerable amounts).

Alternatively you tinker with gravity and say it doesn't work quite the same way on big scales and meddle with the equations to try and fix it up. So far there hasn't been a theory that stacks up with all observed phenomenon.

So we're a little like being in the state where we could use electricity, make a theory of it and equations that work for it, without actually understanding what it's made of.

Simulations of galaxy formation have been done, and if you just include regular matter they don't form (at least in any sensible time). If you throw in the right amount of dark matter, they do form and look much like what we see.

So - the jury is still out on if dark matter really exists as in tangible proof - but I'd say 99% of astronomers believe it does based on multiple lines of evidence, many of them relying on it in every day experiments and observations.