Reasons To Be Cheerful - Part Whatever
ChatterBank3 mins ago
Centre Of The Universe
Where is it - where did the big bang actually take place?
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jim, as a sort of tangential question, what does that do for the meaning of "universe" and "universe"? It usually implies "everything"; would that no longer be the case? It's quite a philosophical leap from there to "sort of everything except for the other stuff".
(This isn't just a vocabulary query, obviously.)
(This isn't just a vocabulary query, obviously.)
If you scroll down on this article. there's a picture of the 'Omniverse'. I don't claim to understand it but you guys might.
http://
http://
In technical terms I think a Universe would be described as a "disconnected 4-dimensional manifold". Then the hyper-universe would be the 5+ dimensional surface in which several such disconnected universes are embedded.
The picture equivalent might be to go back to a balloon again, call that the hyper-universe, and then draw different pictures on it that are separate. Then each universe is essentially two dimensional but supported by a three-dimensional object. If you just draw them on then they are fixed and can't move, but suppose they were attached in a looser sense, they could move about and even collide. You can imagine that such an event could be dramatic.
The picture equivalent might be to go back to a balloon again, call that the hyper-universe, and then draw different pictures on it that are separate. Then each universe is essentially two dimensional but supported by a three-dimensional object. If you just draw them on then they are fixed and can't move, but suppose they were attached in a looser sense, they could move about and even collide. You can imagine that such an event could be dramatic.
There are some rather speculative expeiments looking for rings in the background radiation maps as 'evidence' of colliding Universes!
Was there a before rather depends on getting General Relativity to marry in with Quantum Mechanics.
I'm committing all sorts of sins suggesting that as you run backwards you get to zero and time stops - it's an interpretation of a singularity which is rather scientific herasy
A singularity means the maths has broken down
Thing is I'm from an experimentalist background - I look at it and ask 'is there any reason to believe there was a before ?'
'is there anything that we can't explain that having a before helps us answer?'
And I tend to think not so invoking Occam's Razor I ask for a reason
Was there a before rather depends on getting General Relativity to marry in with Quantum Mechanics.
I'm committing all sorts of sins suggesting that as you run backwards you get to zero and time stops - it's an interpretation of a singularity which is rather scientific herasy
A singularity means the maths has broken down
Thing is I'm from an experimentalist background - I look at it and ask 'is there any reason to believe there was a before ?'
'is there anything that we can't explain that having a before helps us answer?'
And I tend to think not so invoking Occam's Razor I ask for a reason
-- answer removed --
-- answer removed --
Someone once explained to me that any hypothetical 'before' universe is, quite literally, academic, since no 'information' is able to survive the 'big crunch'.
By information, I mean waves, particles, fields, forces, anything capable of influencing the behaviour of anything else or leaving detectable remnants behind is obliterated.
The tricky part is that, by extension this means that 'space' has to be drawn into the crunch and destroyed along with everything else and the limit of my understanding is that space has no physical substance. I get that gravity can cause it to bend but that's only on the local scale. If space initially expanded far faster than matter could follow, then its outermost reaches must, by now, be far out of reach of ever being drawn back by gravity, even if a collapsing universe managed to concentrate a lot of matter back together.
Having the universe make a number of false starts (like a car on a damp morning) is a fun concept but I gather there is another aspect - something about a matter/antimatter annihilation phase and the visible universe being the fraction of a percent of imbalance in the two quantities produced by the big bang.
By information, I mean waves, particles, fields, forces, anything capable of influencing the behaviour of anything else or leaving detectable remnants behind is obliterated.
The tricky part is that, by extension this means that 'space' has to be drawn into the crunch and destroyed along with everything else and the limit of my understanding is that space has no physical substance. I get that gravity can cause it to bend but that's only on the local scale. If space initially expanded far faster than matter could follow, then its outermost reaches must, by now, be far out of reach of ever being drawn back by gravity, even if a collapsing universe managed to concentrate a lot of matter back together.
Having the universe make a number of false starts (like a car on a damp morning) is a fun concept but I gather there is another aspect - something about a matter/antimatter annihilation phase and the visible universe being the fraction of a percent of imbalance in the two quantities produced by the big bang.
"/ I recall talking to you years ago about this when you insisted there was nothing before the big bang //
Funny how science evolves. One minute you're definitely talking rubbish, then later it turns out you might not be."
That's because people often seem to talk about Science as if it's a set of ideas about how the Universe works, but really it's a methodology for trying to arrive at the ideas in the first place. The method -- of investigating, accounting for errors, testing competing theoretical models, designing better models and experiments, and rinse and repeat -- is undeniably the best method for trying to understand our Universe. The theories that then emerge have survived testing so rigorous that it's safe to assume that -- as far as they go, at least -- they are correct. But that doesn't rule out a better theory coming along later, whose job it is to match all that has gone before while providing something new.
In this process, inevitably, some ideas get cast by the wayside, but sometimes they can be picked up again later when someone else manages to find out what the flaw in the idea was and how to repair it. Or, perhaps, someone makes a wild speculation that can't be substantiated (and, so, cannot be called "Science" at the time) but can be tested later, and does pass the test.
One interesting example of this would be the fact that, in a way, Isaac Newton "predicted" the Graviton. We still don't know if this particle (the particle that is responsible for carrying gravity) exists, but the idea has gained for more popularity in the modern age and models can be very sophisticated. Isaac Newton's prediction of it comes from his observation that his own Theory of Gravity demanded the idea of masses being able to influence each other across the cosmos instantly with nothing passing between. This idea of "action at a distance" has always been troubling -- it bothered Einstein centuries later in a different way -- so Newton wondered if later something else travelling between the two masses might exist (his speculation was deliberately limited by himself, but it's clear that he expected his theory not to be the final story*):
"It is inconceivable that inanimate brute matter should, without the mediation of something else which is not material, operate upon and affect other matter, without mutual contact, as it must do if gravitation in the sense of Epicurus be essential and inherent in it. And this is one reason why I desired you would not ascribe 'innate gravity' to me. That gravity should be innate, inherent, and essential to matter, so that one body may act upon another at a distance, through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it. Gravity must be caused by an agent acting constantly according to certain laws; but whether this agent be material or immaterial, I have left to the consideration of my readers."
Not surprising, since Newton thought of light as particles too, so he was a fan of "corpuscular" theories. But the idea was dropped, as the concept of a "field" was developed, and then picked back up again later.
The idea that there was something before our present Universe, similarly, is one that has little or nothing to support it, and is unlikely ever to be testable either. The Big Bang is likely to have acted in a manner similar to shaking the Etch-A-Sketch to clear it of all that came before, so that there may just as well have been nothing as something. But it's still worth a certain amount of speculation as perhaps someone later will come up with a method of testing the idea. At the moment, I highly doubt this -- and so the idea is, for the moment, "ridiculous". But then, so are lots of ideas until the world is ready for them.
Funny how science evolves. One minute you're definitely talking rubbish, then later it turns out you might not be."
That's because people often seem to talk about Science as if it's a set of ideas about how the Universe works, but really it's a methodology for trying to arrive at the ideas in the first place. The method -- of investigating, accounting for errors, testing competing theoretical models, designing better models and experiments, and rinse and repeat -- is undeniably the best method for trying to understand our Universe. The theories that then emerge have survived testing so rigorous that it's safe to assume that -- as far as they go, at least -- they are correct. But that doesn't rule out a better theory coming along later, whose job it is to match all that has gone before while providing something new.
In this process, inevitably, some ideas get cast by the wayside, but sometimes they can be picked up again later when someone else manages to find out what the flaw in the idea was and how to repair it. Or, perhaps, someone makes a wild speculation that can't be substantiated (and, so, cannot be called "Science" at the time) but can be tested later, and does pass the test.
One interesting example of this would be the fact that, in a way, Isaac Newton "predicted" the Graviton. We still don't know if this particle (the particle that is responsible for carrying gravity) exists, but the idea has gained for more popularity in the modern age and models can be very sophisticated. Isaac Newton's prediction of it comes from his observation that his own Theory of Gravity demanded the idea of masses being able to influence each other across the cosmos instantly with nothing passing between. This idea of "action at a distance" has always been troubling -- it bothered Einstein centuries later in a different way -- so Newton wondered if later something else travelling between the two masses might exist (his speculation was deliberately limited by himself, but it's clear that he expected his theory not to be the final story*):
"It is inconceivable that inanimate brute matter should, without the mediation of something else which is not material, operate upon and affect other matter, without mutual contact, as it must do if gravitation in the sense of Epicurus be essential and inherent in it. And this is one reason why I desired you would not ascribe 'innate gravity' to me. That gravity should be innate, inherent, and essential to matter, so that one body may act upon another at a distance, through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it. Gravity must be caused by an agent acting constantly according to certain laws; but whether this agent be material or immaterial, I have left to the consideration of my readers."
Not surprising, since Newton thought of light as particles too, so he was a fan of "corpuscular" theories. But the idea was dropped, as the concept of a "field" was developed, and then picked back up again later.
The idea that there was something before our present Universe, similarly, is one that has little or nothing to support it, and is unlikely ever to be testable either. The Big Bang is likely to have acted in a manner similar to shaking the Etch-A-Sketch to clear it of all that came before, so that there may just as well have been nothing as something. But it's still worth a certain amount of speculation as perhaps someone later will come up with a method of testing the idea. At the moment, I highly doubt this -- and so the idea is, for the moment, "ridiculous". But then, so are lots of ideas until the world is ready for them.
// That's because people often seem to talk about Science as if it's a set of ideas about how the Universe works, but really it's a methodology for trying to arrive at the ideas in the first place. //
Ok to be strictly correct then, what I should have said was 'Funny how the currently accepted set of ideas about how the Universe works
evolves. One minute you're definitely talking rubbish, then later it turns out you might not be'.
Ok to be strictly correct then, what I should have said was 'Funny how the currently accepted set of ideas about how the Universe works
evolves. One minute you're definitely talking rubbish, then later it turns out you might not be'.
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