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mike Meehan

So Now We Know?

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According to the Horizon program on Aunty Beeb last night, the extent of the universe is infinite, we have both dark matter and dark energy in the universe - the dark matter is holding the universe together but the dark matter is driving it apart, however as it does so it becomes weaker because it is having to cover more volume - a bit like adiabatic cooling I suppose - so from that I take it that a point will be reached where the energy and the matter balance out and the expansion will stop?

The other matter is that there may be an infinite number of other universes , which was no more than hinted at but it is suggested that as satellite observations inproves, more evidence to support this may be forthcoming and as it is there is a goods possibility that its authenticity could be checked against the 'background radiation from the big bang which could go towards supporting this theory.

We really do live in exciting times as far as the subject of cosmology is concerned.

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Ummmm.... does this mean that 'Steady State' is back on the agenda?

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This is quite an old theory which again harks back to Quantum Mechanics, particle duality, decoherence and wavefunction collapse (or lack of), and has been discussed a little previously here. In this interpretation, the infinite universes don't occupy the same space - that is, they are physically untouchable by us, and exist as a superposition of states rather than a place where an infinite number of you's and me's exist (one's enough!).

If this were the case, and forgive me as I didn't watch the programme, but how will satellite observations help to find evidence? You can't directly look at them, should they even exist, let alone with a humble satellite.. I'm not sure how the CMB fits in either.

Pointers genuinely welcome.

There is a suggestion that 'bruises' may show in the CMB where multiverses have 'touched' one another. 'They' suggest that interactions with other universes may have occurred in the very early moments of expansion and would show up as irregularities (hotter, cooler, more dense, less dense - they don't say), and that sharper mapping of the CMB (through better satellites!) and complex algorithms may be able to pick these out. These algorithms have already found 15 areas of potential interest. We'll see...

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I'll watch in on i-player later on, if it's on....but I agree with QS, it sounds like it's old hat, not fitting in with current theoretical physics...M-theory and it's subset's String-theory & Brane-World cosmology still rules the roost for me..i.e infers dark matter is in fact the gravitational tug of ordinary matter in a parallel universe separated from our 3D universe by extra dimensions, and dark energy (cosmological constant) is the 'bounce force' pushing our 3-brane away from our 'sister' 3-brane and the force attracting our 3-brane to our 'sister' 3-brane depending on how one views it......sorry if I'm going off topic, but at least M-theory holds the possibilities of detecting the presence of parallel universes (by measuring the force of gravity on the minute scale...i.e does the inverse square law hold true at the microscopic level?)

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As it stands at the moment we exist somewhere within the one and only universe,unless the existance of other universes can be proven..............................

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As it stands at the moment we exist somewhere within the one and only universe,unless the existance of other universes can be proven..............................

Well, in an infinite single universe where there is an infinite amount of time and and infinite amount of space, there'd also be an infinite amount of possibilities.

So if this is true then there ARE an infinite amount of universes within this universe filling every part of it.

That would be the only thing that would make sense really wouldn't it?

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Well, in an infinite single universe where there is an infinite amount of time and and infinite amount of space, there'd also be an infinite amount of possibilities.

So if this is true then there ARE an infinite amount of universes within this universe filling every part of it.

That would be the only thing that would make sense really wouldn't it?

but just to throw a spanner in the works, physicists hate the word 'infinite' or 'infinity' due to the fact that as their theories are written in mathematics, then an infinity simply means that their equations are flawed, therefore their theories are incorrect!......Sorry to keep banging on about M/String theory, but with this wonderfully elegant theory, the infinities disappear, and indeed it marries the theories of the large (Relativity) with the small (Quantum Theory) something that the standard model fails to do

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I think the point here is that the multiverse theory that is being suggested lately does not need superposition. They are universes that exist in a different place, but were once squashed together at the start. The only vaguely interesting thing about the latest theory is that it may actually be testable - if these bruises can be found then at least there is some evidence that may support the theory. I must admit, modern cosmology seems to suffer from the 'theory to prove a theory' rabbit hole - e.g. what we see does not explain the movement of galaxies - ah! Dark Matter must exist, which must slow the expansion. To test it, they measured that. Oh bugger - it's accelerating! Ah - dark energy was invented to explain why dark matter is not slowing it down. Neither dark matter nor dark energy have been observed to any degree of confidence. So instead of revisiting the existing laws of gravity / GR we appear (to my numpty brain) to be down a rabbit hole that may take many years to back out from.

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I think the point here is that the multiverse theory that is being suggested lately does not need superposition. They are universes that exist in a different place, but were once squashed together at the start. The only vaguely interesting thing about the latest theory is that it may actually be testable - if these bruises can be found then at least there is some evidence that may support the theory. I must admit, modern cosmology seems to suffer from the 'theory to prove a theory' rabbit hole - e.g. what we see does not explain the movement of galaxies - ah! Dark Matter must exist, which must slow the expansion. To test it, they measured that. Oh bugger - it's accelerating! Ah - dark energy was invented to explain why dark matter is not slowing it down. Neither dark matter nor dark energy have been observed to any degree of confidence. So instead of revisiting the existing laws of gravity / GR we appear (to my numpty brain) to be down a rabbit hole that may take many years to back out from.

My understanding is that your highlighted quote is not strictly true....dark energy wasn't invented as such, rather it was re-discovered, as what had been dubbed 'dark energy' is almost certainly nothing more than Einstein's 'Cosmological Constant' which Einstein added to his original theory of relativity to try and support a static universe, however in modern physics, more explicitly the Standard Model , the mathematics have shown the cosmological constant in Einstein's equations could be physically represented in our universe as the energy density of the universe, ie a CC of 0 means a flat universe, a slightly positive CC will result in an accelerating expansion of the universe, a CC which is not infact constant but grows would result in an exponential expansion of the using culminating in a 'Big Rip' scenario, although this scenario has been widely discounted now, and a negative CC would result in a 'closed universe' scenario, culminating in a 'Big Crunch' scenario. Observations back in 1998 inferred that the CC was slightly positive

just seen FFO at the bottom of the thread, if memory serves me correctly (forgive me if I'm wrong) he has some serious knowledge of the mathematics in question and hopefully can shed some more light on this smile.png

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Fair point AJ, it was re-invented as a convenient explanation when everyone said "whoa!" when the universe didn't conform to dark matter theory. Since then, CC (again) and non-constant scalar fields (Higgs anyone?) have become fashionable. My point remains - theories to explain theories have always been a potential route to wasted effort. I'm not in any position to say this is so (no-one is at the mo) but I really wish there were more unfashionable physicists than there are.

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Fair point AJ, it was re-invented as a convenient explanation when everyone said "whoa!" when the universe didn't conform to dark matter theory. Since then, CC (again) and non-constant scalar fields (Higgs anyone?) have become fashionable. My point remains - theories to explain theories have always been a potential route to wasted effort. I'm not in any position to say this is so (no-one is at the mo) but I really wish there were more unfashionable physicists than there are.

I don't disagree with you there, no matter what theory is 'en vogue' there will always be someone who will shout out "so, theory-x is correct, so now we need a theory to explain why theory-x is correct"......and so on...but at least by always asking these questions we can expand our knowledge not just on our IMO insignificant speck of a universe on the grander scales of things, but expand our knowledge on the very possibilities of all forms of existence & reality..

The danger as you very correctly pointed out is that some theories, maybe even theories currently lauded might well be red herrings and dead ends, again I presume that only by exploring these theories will we find out.....and I agree with your point about 'unfashionable' physics in so much as the modern explosion of theoretical physics rocks the 'status-quo' of the conformists and some of the up and coming physicists are labelled as too radical & as heretics!

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but just to throw a spanner in the works, physicists hate the word 'infinite' or 'infinity' due to the fact that as their theories are written in mathematics, then an infinity simply means that their equations are flawed, therefore their theories are incorrect!......Sorry to keep banging on about M/String theory, but with this wonderfully elegant theory, the infinities disappear, and indeed it marries the theories of the large (Relativity) with the small (Quantum Theory) something that the standard model fails to do

But if we were to divide 4 by 2 = 2, then divide 2 by 2 = 1 then 1 by 2 = 0.5, then 0.5 by 2 = 0.25 and so on, we never actually reach zero and this division could carry on for infinity, so mathmatically it must exist, or have I got this wrong?

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But if we were to divide 4 by 2 = 2, then divide 2 by 2 = 1 then 1 by 2 = 0.5, then 0.5 by 2 = 0.25 and so on, we never actually reach zero and this division could carry on for infinity, so mathmatically it must exist, or have I got this wrong?

I should've have pointed out that what I meant was if the solution to the equation is an infinity then the equation is flawed. In your scenario Mike, yes the division can be carried on an infinite number of times, but it will always give you a finite answer smile.png

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Fair point AJ, it was re-invented as a convenient explanation when everyone said "whoa!" when the universe didn't conform to dark matter theory. Since then, CC (again) and non-constant scalar fields (Higgs anyone?) have become fashionable. My point remains - theories to explain theories have always been a potential route to wasted effort. I'm not in any position to say this is so (no-one is at the mo) but I really wish there were more unfashionable physicists than there are.

IMHO, not really being qualified at all and an absolute duffer as far as the maths are concerned, I think that very often progress can be made by thinking out of the box.

Or what was it some said about when investigating something like this and all the lines are shown to be impossible, then the impossible becomes possible.

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It's like Zeno's paradox. If you go the other way, it adds up to one smile.png

Good grief I just mentioned him in another thread. Osborne can never catch up with Gordon. Like the tortoise.

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This is quite an old theory which again harks back to Quantum Mechanics, particle duality, decoherence and wavefunction collapse (or lack of), and has been discussed a little previously here. In this interpretation, the infinite universes don't occupy the same space - that is, they are physically untouchable by us, and exist as a superposition of states rather than a place where an infinite number of you's and me's exist (one's enough!).

If this were the case, and forgive me as I didn't watch the programme, but how will satellite observations help to find evidence? You can't directly look at them, should they even exist, let alone with a humble satellite.. I'm not sure how the CMB fits in either.

Pointers genuinely welcome.

As the program said - if you were to draw a triangle on the face of the earth with the base line was along the souther states of America and the apex was at the north pole, it would not be a true triangle and the sum of the angles would be greater than 180 degrees because the earth is a sphere and the lines would in fact be following great circle routes.

After that it gets more complicated but is based on making measurements with a triangle - as light travels through space, it can be bent by various gravitational influences - by making an extemely thin triangle with the base being a line between two satellites and the apex at the end of the observable universe, they were able to differentiate between a finite spherical universe which is collapsing, or one which is expanding, then if the angles did make up 180 degrees their result was that the universe is flat and infinite. About this point I am getting completly lost, so I have to trust that they know what they are talking about.

However I find the whole concept of finity and infinity, multi universes, parallel universes, fifth dimensions and more absolutely fascinating and believe that as we find out more we will understand some of the things mankind has wondered about since the dawn of time.

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I should've have pointed out that what I meant was if the solution to the equation is an infinity then the equation is flawed. In your scenario Mike, yes the division can be carried on an infinite number of times, but it will always give you a finite answer smile.png

Yes, but isn't that only if you stop at a specific point along the way?

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Yes, but isn't that only if you stop at a specific point along the way?

No, there will always be a finite solution, no matter how many times you divide....the only way you would get to zero is to divide zero by itself, and using your halving equation, you'd never get to that scenario

to save any possible confusion is that if you have an equation, say for example a simple equation that shows the following solution....if A & B are finite numbers then "A / B = ∞"....then the equation is flawed

...I think?

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Why do people always look Gore's an 'edge' to things , a start , middle and end?

It's better to leave you mind wide open to everything you can , that way you don't miss anything.

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No, there will always be a finite solution, no matter how many times you divide....the only way you would get to zero is to divide zero by itself, and using your halving equation, you'd never get to that scenario

to save any possible confusion is that if you have an equation, say for example a simple equation that shows the following solution....if A & B are finite numbers then "A / B = ∞"....then the equation is flawed

...I think?

The mind boggles:)

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