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Infinite Or Closed Universe
Can any of the scientific minds here please tell me what the current scientific understanding of the universe is at the present? (or at least the general consensus). Is it closed or infinite?
I have trouble wrapping my head around either model. Is there another one that I havnt heard about.
Thanks.
I have trouble wrapping my head around either model. Is there another one that I havnt heard about.
Thanks.
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It seems to me that it rather depends on the particular branch of science that's up for debate. I really can't see why anyone should begrudge the idea that scientists would be the ones you'd turn to to answer questions about something so pure and theoretical as this one. It seems a natural consequence of the general principle that, by and large, the more you've studied a subject the more qualified you are to talk about it. I wouldn't ask a lawyer questions about particle physics, and I wouldn't ask a particle physicist questions about law (at least, in neither case would I rely on the answers given).
On the other hand, when science intersects with public policy the topic clearly becomes more open -- not so much because other people know more than scientists but because what you do with the answer starts to matter. I mean, I would love people to listen more seriously to, for example, climate scientists, and make policy accordingly, but there is clearly no obligation to, and sometimes it makes sense for public policy to lag behind the best current scientific advice. Even if that's not a problem, the answers they give, and the recommendations they make, must then be weighed against other considerations.
For matters theoretical, though, it stands to reason that there are benefits to asking people who have made a career of studying them -- either directly or through the popular science books, written by people who asked the questions for you.
On the other hand, when science intersects with public policy the topic clearly becomes more open -- not so much because other people know more than scientists but because what you do with the answer starts to matter. I mean, I would love people to listen more seriously to, for example, climate scientists, and make policy accordingly, but there is clearly no obligation to, and sometimes it makes sense for public policy to lag behind the best current scientific advice. Even if that's not a problem, the answers they give, and the recommendations they make, must then be weighed against other considerations.
For matters theoretical, though, it stands to reason that there are benefits to asking people who have made a career of studying them -- either directly or through the popular science books, written by people who asked the questions for you.
Jim, No one begrudges the idea of asking scientists questions. The problem arises when the answers become so hifalutin that the layman is given the impression – or even told outright – that the subject is beyond his comprehension. While that pretentious attitude may massage egos it does little to encourage interest – and since I like to encourage people regardless of IQ or background to ask questions – for therein lies the road to education - that, in my opinion, is a great pity. I mean, really! Apart from the fact that few come here to be lectured at length, what is the point of talking about ‘a four-dimensional compact Lorentzian Manifold’ to the layman? That’s the sort of thing that has eyes glazing over and minds beating a hasty retreat to pastures more conducive to pleasantly animated discussion that’s open for all to add their two-pennyworth.
"I think people tend to have this idea that the Big Bang is when the Universe was of zero size, so that a finite time later it would still be finite -- and therefore it can't possibly be infinite now -- but, again, what was increasing wasn't the size of the Universe but the distance between given points within it."
That's all very well, as is the balloon analogy, but it seems to be less clear when one considers the idea of running time backwards and finding a point when all is at the same infinitely dense point. You get your infinitely small but finite balloon starting point anyway. One needs a different vision for it to be already infinite somehow.
That's all very well, as is the balloon analogy, but it seems to be less clear when one considers the idea of running time backwards and finding a point when all is at the same infinitely dense point. You get your infinitely small but finite balloon starting point anyway. One needs a different vision for it to be already infinite somehow.
It's worth noting that I avoided bringing any technical language to the thread until rather late on -- when I figured it was worth making the point that the mathematics, at least, is very well-understood. Beyond that it's a matter of taste how much or how little to hold back about the subject at hand. I do my best to make the subjects I am talking about accessible, but it does rather depend on the subject audience, how interested they are, what background they have and so on.
But an unspoken truth that, at some point, has to be acknowledged, is that science at the cutting edge is ridiculously technical. Long gone are the days when giants of the field such as Poincare, Einstein and the like could reasonably call themselves experts at essentially everything under the Sun. It's perhaps a loss to science that such people are rather a lot rarer these days, but it's also a somewhat inevitable result of progress.
That's not to mean that it's inaccessible but people ought to appreciate that there is a certain amount of effort involved in order to understand the subject. The technical language isn't necessary perhaps for a cursory overview -- I think I successfully enough tried to outline the key ideas with reference to a balloon and a cube -- but at some point it simply stops working properly.
Still, let's suppose that's not all true, and that a meaningful discussion can be had without knowing much, if anything at all, about the subject. Or perhaps I should say without being as well-informed as is in principle possible, for "knowing" is indeed too strong a word. But what discussion is there to be had in that case?
By way of comparison, my own contributions to this thread have tried to explain various aspects of the answer as best I can without using the technical language (except, as I said, to make a very specific point about the boundary between physical and mathematical knowledge). On the other hand, your attempt to encourage discussion appears to amount to the following:
"...no one knows, so current scientific understanding isn’t really relevant at all."
"... it can only be a best guess ..."
"no one knows..."
"[Stephen Hawking] doesn't know either."
"Ultimately no one knows - but it's good to hypothesise."
"there's more to the universe than mathematics."
Which I can't help but feel has done very little to advance the "discussion" that you crave so much. I mean, perish the thought that informed observation and at least an *attempt* to explain the current scientific understanding should enter into any discussion about the subject, when that is expressly what was asked for in the first place!
I'm really pleased to see questions like this, like you as well. What I am trying to do is to provide an answer that deliberately is trying to paint the picture that the answers I give are incomplete and that, therefore, there is more research for the questioner to do, if they feel so inclined. I'm trying to *introduce* the subject, rather than resolve it. I should hope that encourages people plenty enough. After all, it worked well for me. Hawking's "Universe in a Nutshell" is filled with technical gobbledegook that twelve-year-old me had not a hope of understanding (and some of it I still don't) -- but it was at that moment that, thrilled by the thought of being able to one day, I set myself on the path to where I am now. I rather suspect that had his book started with "I don't know anything" and then spent the next hundred pages ranting at anyone who dared attempt to pretend that learning some maths might help them understand the answers (or our best attempts at the answers) better, he might have been rather less successful in encouraging me, and others like me, to follow in his footsteps.
But an unspoken truth that, at some point, has to be acknowledged, is that science at the cutting edge is ridiculously technical. Long gone are the days when giants of the field such as Poincare, Einstein and the like could reasonably call themselves experts at essentially everything under the Sun. It's perhaps a loss to science that such people are rather a lot rarer these days, but it's also a somewhat inevitable result of progress.
That's not to mean that it's inaccessible but people ought to appreciate that there is a certain amount of effort involved in order to understand the subject. The technical language isn't necessary perhaps for a cursory overview -- I think I successfully enough tried to outline the key ideas with reference to a balloon and a cube -- but at some point it simply stops working properly.
Still, let's suppose that's not all true, and that a meaningful discussion can be had without knowing much, if anything at all, about the subject. Or perhaps I should say without being as well-informed as is in principle possible, for "knowing" is indeed too strong a word. But what discussion is there to be had in that case?
By way of comparison, my own contributions to this thread have tried to explain various aspects of the answer as best I can without using the technical language (except, as I said, to make a very specific point about the boundary between physical and mathematical knowledge). On the other hand, your attempt to encourage discussion appears to amount to the following:
"...no one knows, so current scientific understanding isn’t really relevant at all."
"... it can only be a best guess ..."
"no one knows..."
"[Stephen Hawking] doesn't know either."
"Ultimately no one knows - but it's good to hypothesise."
"there's more to the universe than mathematics."
Which I can't help but feel has done very little to advance the "discussion" that you crave so much. I mean, perish the thought that informed observation and at least an *attempt* to explain the current scientific understanding should enter into any discussion about the subject, when that is expressly what was asked for in the first place!
I'm really pleased to see questions like this, like you as well. What I am trying to do is to provide an answer that deliberately is trying to paint the picture that the answers I give are incomplete and that, therefore, there is more research for the questioner to do, if they feel so inclined. I'm trying to *introduce* the subject, rather than resolve it. I should hope that encourages people plenty enough. After all, it worked well for me. Hawking's "Universe in a Nutshell" is filled with technical gobbledegook that twelve-year-old me had not a hope of understanding (and some of it I still don't) -- but it was at that moment that, thrilled by the thought of being able to one day, I set myself on the path to where I am now. I rather suspect that had his book started with "I don't know anything" and then spent the next hundred pages ranting at anyone who dared attempt to pretend that learning some maths might help them understand the answers (or our best attempts at the answers) better, he might have been rather less successful in encouraging me, and others like me, to follow in his footsteps.
OG -- indeed, the "balloon" analogy is unhelpful when trying to deal with finite v. infinite universes. I can't really think at the moment of an analogy that properly explains how something can be infinite and yet infinitely dense, because it would appear to defy common sense.
Maybe later I'll be able to come up with something, but for now I just wanted to say that the balloon analogy was only meant to explain one aspect of what's going on rather than all of it.
Maybe later I'll be able to come up with something, but for now I just wanted to say that the balloon analogy was only meant to explain one aspect of what's going on rather than all of it.
//Does it matter?//
Well, it does if your interested in science, astronomy, maths, physics, quantum physics, philosophy, etc.
Have to admit, ive just read all of this thread with great interest...not much understanding mind...but great interest. I'm seriously in awe of the minds of some on here who can wrap their heads around this stuff and thank you for replies. (Hope it carries on a bit longer, I'm enjoying it :-) )
Well, it does if your interested in science, astronomy, maths, physics, quantum physics, philosophy, etc.
Have to admit, ive just read all of this thread with great interest...not much understanding mind...but great interest. I'm seriously in awe of the minds of some on here who can wrap their heads around this stuff and thank you for replies. (Hope it carries on a bit longer, I'm enjoying it :-) )
Thanks Jim. My ex's son is currently at Warwick Uni studying physics. As a child he baffled me with talk of quantum mechanics and theories of time travel (all self researched). People all thought there was something a little odd with him (at one point he was tested for autism) Turned out he was something of a genius :-)
Jim, //Which I can't help but feel has done very little to advance the "discussion" that you crave so much.//
I do believe you’re smarting. My comments may not have advanced the discussion much but hopefully they have encouraged people to understand that familiarity with ‘a four-dimensional compact Lorentzian Manifold’ is not an essential requirement to participate. Ultimately we’re talking about a hypothetical scenario and therefore their ideas are just as worthy as others – and from my point of view at least, just as welcome.
I do believe you’re smarting. My comments may not have advanced the discussion much but hopefully they have encouraged people to understand that familiarity with ‘a four-dimensional compact Lorentzian Manifold’ is not an essential requirement to participate. Ultimately we’re talking about a hypothetical scenario and therefore their ideas are just as worthy as others – and from my point of view at least, just as welcome.
We seem to be moving closer to a philosophical discussion -- not that I have a problem with that, but it does feel like our two philosophies are basically incompatible.
For example, your last point seems to me to need some qualification at least. I absolutely accept that anyone can offer up ideas, regardless of what they do or do not know. But would it not be fair to say that such ideas can be critically evaluated, either against empirical evidence or against mathematical principles, and therefore either rejected or at least deemed highly implausible? If you accept that, would it not then follow that being already aware of such evidence/mathematics is beneficial to make such evaluations, and comment on what is -- and is not -- likely to be a fruitful direction of thought?
Put another way, while you might not think that knowledge of the properties of "four-dimensional compact Lorentzian manifolds" is essential to participate, would you not agree that it's probably *useful*? And if not, why not? What *do* you think is useful/essential to participate? What ideas would you personally like to offer to the discussion?
There can never be any certainty about anything in Physics, but it does seem that you have a habit of taking this statement too literally, and not allowing for the possibility of greater confidence in one idea over another. If that's a mistaken impression I apologise, but it's one I find hard to avoid given our various discussions over the years.
For example, your last point seems to me to need some qualification at least. I absolutely accept that anyone can offer up ideas, regardless of what they do or do not know. But would it not be fair to say that such ideas can be critically evaluated, either against empirical evidence or against mathematical principles, and therefore either rejected or at least deemed highly implausible? If you accept that, would it not then follow that being already aware of such evidence/mathematics is beneficial to make such evaluations, and comment on what is -- and is not -- likely to be a fruitful direction of thought?
Put another way, while you might not think that knowledge of the properties of "four-dimensional compact Lorentzian manifolds" is essential to participate, would you not agree that it's probably *useful*? And if not, why not? What *do* you think is useful/essential to participate? What ideas would you personally like to offer to the discussion?
There can never be any certainty about anything in Physics, but it does seem that you have a habit of taking this statement too literally, and not allowing for the possibility of greater confidence in one idea over another. If that's a mistaken impression I apologise, but it's one I find hard to avoid given our various discussions over the years.
I still say my preferred model - a Universe infinite in both time and space - fits the bill. Jim, what evidence is there to suggest anything other than that exists? Or are these theories simply a way of deflecting thought away from the uncomfortable idea of infinity. Quite honestly, as uncomfortable as I am with infinity I can accept it far more readily than I can some of these other ideas, particularly those that involve a "fourth dimension".
NJ -- the "fourth dimension" is time, so I am not sure that it should make you too uncomfortable. As for the rest of your post: if one takes the Big Bang theory at face value, then the Universe is (effectively) finite in time -- it has a definite beginning, and may or may not have a definite end. But what I said about space wasn't that it *isn't* infinite, but rather that we can't really *know* this with absolute certainty. Our observations will, most likely, be limited to a universe within about 100 billion light years of us, give or take, so that technically leaves the issue of whether we are in an infinite universe, or one that is finite but closed, as an open question. That's all I meant. In this context, at least, I don't think anyone is uncomfortable with the idea of infinite space, but scientists are all the same on the lookout for other possibilities.
In the light of how this thread has gone while I’ve been hard at work earning a crust, I’m going to add some comments that have been concerning me for some time.
First, I support everything Jim has said.
Moving the debate on from that, most of us who have a science-based education are concerned about the de-valuation of peer-reviewed research evidence.
As Jim says, that kind of work requires effort. In some cases, a lot of effort. It is not closed off to anyone, but getting to an advanced level of understanding all kinds of things, such as anti-biotic resistance, climate change, gravity, or cosmology – or for that matter the culture of the ancient Sumerians – takes time and effort.
Many of the issues facing the world today – from Climate change to water scarcity, to care of the elderly – are complex and require similarly complex solutions.
It worries me that it is becoming a widespread and fashionable view to reject what ‘experts’ say (I think it was Gove who famously said that he has had enough of experts), in favour of a simplistic ‘solution’ that gains thousand tweets or Facebook likes.
The current US president (among others) rejects Climate Change. It is surely no coincidence that he and his friends at the top of global corporations stand to gain from a legislative environment that ignores the damage we are doing to the planet – damage that future generations will have to manage.
This kind of attitude is turning our society into a post-truth environment where a media outlet with a strong political agenda can publish a fake news story and have it re-tweeted a thousand or more times, even though there is peer-reviewed science that demonstrates the story and re-tweets are complete fabrications.
We see this more and more. As newspapers have suffered from loss of advertising revenues, they have morphed into clickbait sites that will do anything to increase the clicks in order to boost their revenues – and simultaneously promote the values of their proprietors.
To the point where the part of Fox Entertainment that calls itself “Fox News” is essentially an entertainment channel so that it can get away with publishing outright lies, or party-political output on behalf for the US Republican Party. And yet, evidence shows that there is a large subset of the population in the United States that believes Fox is a credible news source.
Furthermore, we have sites hosted by Russians and others who deliberately put up false information in order to attract clicks and re-tweets among a public that is desperate to hear easy solutions to difficult problems.
But that’s probably too far off-topic.
What I see is powerful people and organisations deliberately de-valuing evidence-based conclusions, so that they can further their own agendas against the interests of the mass of the population.
Anyone who chooses to avoid making the effort to understand it, or give the ‘experts’ a fair hearing, is playing into their hands.
I choose to do what I can against that agenda. I’ve been fortunate to have a very good education and maybe have a half-way decent brain and have spent a lifetime listening to people from many different backgrounds and parts of the world. I choose to pay forward by trying to help public understanding of some of these issues.
But just to lighten the tone… The thing is, the experts (quite possibly me included) often don’t do themselves any favours. Research (see below) suggests that to gain credibility, those experts have to have a persona that is warm and friendly as well as having the requisite expertise.
https:/
First, I support everything Jim has said.
Moving the debate on from that, most of us who have a science-based education are concerned about the de-valuation of peer-reviewed research evidence.
As Jim says, that kind of work requires effort. In some cases, a lot of effort. It is not closed off to anyone, but getting to an advanced level of understanding all kinds of things, such as anti-biotic resistance, climate change, gravity, or cosmology – or for that matter the culture of the ancient Sumerians – takes time and effort.
Many of the issues facing the world today – from Climate change to water scarcity, to care of the elderly – are complex and require similarly complex solutions.
It worries me that it is becoming a widespread and fashionable view to reject what ‘experts’ say (I think it was Gove who famously said that he has had enough of experts), in favour of a simplistic ‘solution’ that gains thousand tweets or Facebook likes.
The current US president (among others) rejects Climate Change. It is surely no coincidence that he and his friends at the top of global corporations stand to gain from a legislative environment that ignores the damage we are doing to the planet – damage that future generations will have to manage.
This kind of attitude is turning our society into a post-truth environment where a media outlet with a strong political agenda can publish a fake news story and have it re-tweeted a thousand or more times, even though there is peer-reviewed science that demonstrates the story and re-tweets are complete fabrications.
We see this more and more. As newspapers have suffered from loss of advertising revenues, they have morphed into clickbait sites that will do anything to increase the clicks in order to boost their revenues – and simultaneously promote the values of their proprietors.
To the point where the part of Fox Entertainment that calls itself “Fox News” is essentially an entertainment channel so that it can get away with publishing outright lies, or party-political output on behalf for the US Republican Party. And yet, evidence shows that there is a large subset of the population in the United States that believes Fox is a credible news source.
Furthermore, we have sites hosted by Russians and others who deliberately put up false information in order to attract clicks and re-tweets among a public that is desperate to hear easy solutions to difficult problems.
But that’s probably too far off-topic.
What I see is powerful people and organisations deliberately de-valuing evidence-based conclusions, so that they can further their own agendas against the interests of the mass of the population.
Anyone who chooses to avoid making the effort to understand it, or give the ‘experts’ a fair hearing, is playing into their hands.
I choose to do what I can against that agenda. I’ve been fortunate to have a very good education and maybe have a half-way decent brain and have spent a lifetime listening to people from many different backgrounds and parts of the world. I choose to pay forward by trying to help public understanding of some of these issues.
But just to lighten the tone… The thing is, the experts (quite possibly me included) often don’t do themselves any favours. Research (see below) suggests that to gain credibility, those experts have to have a persona that is warm and friendly as well as having the requisite expertise.
https:/
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