Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: EvaH on 21/08/2020 13:53:16
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Sadiq asks:
Since light elements are transforming into heavier elements in stars, is it true to predict that one day there will be no new born star?
What do you think?
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Yes. This is part of the heat death scenario of the Universe. Star formation cannot continue forever.
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Sadiq asks:
Since light elements are transforming into heavier elements in stars, is it true to predict that one day there will be no new born star?
What do you think?
No. Probably there are many scientists who predict that the universe is infinite and eternal, and if right, there must be grand scale processes that recycle physical matter into its constituent wave energy, and then parlay that wave energy back into matter across the universe. The universe would be in the perpetual process of recycling its matter and energy in a matter-to-wave energy, wave energy-to-matter scenario.
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No. Probably there are many scientists who predict that the universe is infinite and eternal, and if right, there must be grand scale processes that recycle physical matter into its constituent wave energy, and then parlay that wave energy back into matter across the universe. The universe would continually be in the perpetual process of recycling its matter and energy in a matter-to-wave energy, wave energy-to-matter scenario.
The problem with that is the metric expansion of space. Eventually, every particle will be too far apart from any other particle to interact with it. So you still eventually get heat death. This assumes, of course, that expansion will continue indefinitely. If it stops or reverses, then you can have the eventual reversal of entropy as you say.
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Sadiq asks:
Since light elements are transforming into heavier elements in stars, is it true to predict that one day there will be no new born star?
What do you think?
No. Probably there are many scientists who predict that the universe is infinite and eternal, and if right, there must be grand scale processes that recycle physical matter into its constituent wave energy, and then parlay that wave energy back into matter across the universe. The universe would continually be in the perpetual process of recycling its matter and energy in a matter-to-wave energy, wave energy-to-matter scenario.
The only valid mechanism proposed for this outcome is called "wishful thinking".
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No. Probably there are many scientists who predict that the universe is infinite and eternal, and if right, there must be grand scale processes that recycle physical matter into its constituent wave energy, and then parlay that wave energy back into matter across the universe. The universe would continually be in the perpetual process of recycling its matter and energy in a matter-to-wave energy, wave energy-to-matter scenario.
The problem with that is the metric expansion of space. Eventually, every particle will be too far apart from any other particle to interact with it. So you still eventually get heat death. This assumes, of course, that expansion will continue indefinitely. If it stops or reverses, then you can have the eventual reversal of entropy as you say.
In that post, where I referred to an infinite and eternal universe, I was going on what may be the general consensus that there is expansion of space going on, and the expansion of space would logically result in separation of particles, leading to heat death. But in science there is a re-thinking of generally accepted ideas going on at all times, and if we agree that the current thinking is that space is expanding, there are legitimate questions that have gone unanswered:
What is the universe expanding into?
Is new space coming into existence all the time?
Does the consensus scenario mean that the existing universe is finite, surrounded beyond that by emptiness or nothingness?
Will new stars form in the new space, and out of what?
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In that post I referred to an infinite and eternal universe
For which there is no evidence and against which there has been evidence for some time.
https://en.wikipedia.org/wiki/Olbers'_paradox
But in science there is a re-thinking of generally accepted ideas going on at all times,
Yep.
But science isn't in the habit of ignoring evidence.
We can only look at this universe, and the laws it has lead to a heat death.
Of course, we can't rule out the idea that it gets eaten by a really big dog.
But to say that we think it will, is a it silly.there are legitimate questions that have gone unanswered:
Not all unanswered questions fit that category.
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In that post I referred to an infinite and eternal universe
For which there is no evidence and against which there has been evidence for some time.
https://en.wikipedia.org/wiki/Olbers'_paradox
But in science there is a re-thinking of generally accepted ideas going on at all times,
Yep.
But science isn't in the habit of ignoring evidence.
We can only look at this universe, and the laws it has lead to a heat death.
Of course, we can't rule out the idea that it gets eaten by a really big dog.
But to say that we think it will, is a it silly.there are legitimate questions that have gone unanswered:
Not all unanswered questions fit that category.
Lol, "a really big dog"? Can you be more specific about the evidence that the universe is finite?
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Can you be more specific about the evidence that the universe is finite?
See: https://en.wikipedia.org/wiki/Cosmic_microwave_background
Or, more colloquially:
The CMBR shows that the universe is not eternal - that it was distinctly different in the past compared to now (eg hotter and denser); if the current acceleration of expansion continues, it will be distinctly different in the future compared to now (eg no new stars forming).
The CMBR says that as far as we can see in all directions, all matter was condensed into a much smaller, much hotter fireball until about 300,000 years after the Big Bang.
- There was a finite start to the universe we can see
- Matter was denser then, and less dense now, so if new matter is being created (and there is no evidence for this), it is being created at such a low rate that the density of the universe is declining
- Extrapolating forward, matter will get so sparse that new stars can't form
Whether the universe is infinite or not is unresolved - but it has no bearing on this question.
- You could imagine an infinite number of other observers, so far away from us that light from us will never reach them (or vice versa), so they are beyond our horizon
- But these other observers can only see back to the CMBR too. This forms a horizon in the past beyond which light cannot penetrate
Perhaps some day we will be able to detect relics of the Big Bang in neutrinos or gravitational waves, and that will push back our horizon in the past to perhaps 1 second after the Big Bang.
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What is the universe expanding into?
It doesn't need to be expanding into anything. It's just expanding.
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Can you be more specific about the evidence that the universe is finite?
See: https://en.wikipedia.org/wiki/Cosmic_microwave_background (https://en.wikipedia.org/wiki/Cosmic_microwave_background)
Or, more colloquially:
The CMBR shows that the universe is not eternal - that it was distinctly different in the past compared to now (eg hotter and denser); if the current expansion continues, it will be distinctly different in the future compared to now (eg no new stars forming).
OK, you can say that, so would it be fair to restate that to say, the CMBR implies that the expansion of the observable universe may have had a beginning, perhaps 14 billion years ago or so, because it appears to be expanding and cooling from a much denser and hotter state in the past. The entire universe may or may not equate to the "observable universe" though, so we just don't have enough information to answer the question difinitevly in regard to the entire universe.
The CMBR says that as far as we can see in all directions, all matter was condensed into a much smaller, much hotter fireball until about 300,000 years after the Big Bang.
- There was a finite start to the universe we can see
- Matter was denser then, and less dense now, so if new matter is being created (and there is no eveidence for this), it is being created at such a low rate that the density of the universe is declining
- Extrapolating forward, matter will get so sparse that new stars can't form
Whether the universe is infinite or not is unresolved - but it has no bearing on this question.
Never-the-less, the fact remains that we are only privy to knowledge extracted from the observable universe, so it seems a natural inclination to speculate beyond that, and that speculation takes us out of the realm of Science and into the realm of speculation. But not all speculative questions are out side of the realm of science. Science has to include questions that are open to investigation, as long as there is some consensus amongst the scientific community that the questions are legitimate avenues for investigation. I'm not talking about where Bored Chemist chided me that "some big dog ate it", but valid questions that are being worked by the scientific community.
- You could imagine an infinite number of other observers, so far away from us that light from us will never reach them (or vice versa), so they are beyond our horizon
- But these other observers can only see back to the CMBR too. This forms a horizon in the past beyond which light cannot penetrate
There are interesting scenarios and there are definitely horizon issues when discussing cosmology.Perhaps some day we will be able to detect relics of the Big Bang in neutrinos or gravitational waves, and that will push back our horizon in the past to perhaps 1 second after the Big Bang.
Evidence supports an event, the Big Bang event, perhaps 14 billion years ago, that caused the observed expansion of the observable universe. But are we being too presumptuous if we conclude that the Big Bang was the only such event in all of space and time? If the horizon is receding from us at the speed of light, there is still a finite amount of space across which it would have traveled in the given 14 billion years. What rules out the speculation that there are adjacent amounts of space, and even an endless amount of space beyond? I wouldn't want science to be based solely on such conclusions, but science is busy on advancing in all meaningful directions :)
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Can you be more specific about the evidence that the universe is finite?
More specific than this?
https://en.wikipedia.org/wiki/Olbers%27_paradox
Why? Isn't it enough, or don't you think it goes dark at night?
Never-the-less, the fact remains that we are only privy to knowledge extracted from the observable universe, so it seems a natural inclination to speculate beyond that, and that speculation takes us out of the realm of Science and into the realm of speculation.
Which is pretty much the same as saying
The only valid mechanism proposed for this outcome is called "wishful thinking".
Because the properties of this universe predicta heat death.
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I'm not talking about where Bored Chemist chided me that "some big dog ate it",
Your evidence is exactly as good as that which supports the "dog eats it" hypothesis.
Both are possible. neither has a plausible mechanism.
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What rules out the speculation that there are adjacent amounts of space, and even an endless amount of space beyond?
Notheing.
And nothing rules it in either.
It's a guess.
Stop pretending that it is science rather than wishful thinking.
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What rules out the speculation that there are adjacent amounts of space, and even an endless amount of space beyond?
Notheing.
And nothing rules it in either.
It's a guess.
Stop pretending that it is science rather than wishful thinking.
My mistake. I should be posting in the New Theories sub forum. Obviously if everything points to a future heat death of the universe there must have been a beginning. Do you think that the beginning was a natural event, and do you think that it makes sense that the beginning followed nothingness?
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Obviously if everything points to a future heat death of the universe there must have been a beginning.
Can you explain how that is obvious?
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Obviously if everything points to a future heat death of the universe there must have been a beginning.
Can you explain how that is obvious?
I guess I'm wrong about it being obvious, [shrug]. My suggestion is that the universe has always existed, and will always exist. After thinking about a future heat death, I guess that does not mean that the universe will end. I just don't know where the heat escapes to unless you think the universe is finite and inflating. I always consoled myself that if that was the case, given infinite time, that the heat death would have already occurred if it was going to.
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a future heat death
One of the misleading things about the "heat death of the universe" is that it is not hot.
In fact, it is very close to absolute zero - much closer than the current CMBR, which has a temperature of 2.7 degrees above absolute zero.
When everything has the same, low temperature, it is not possible for machines to work off a temperature difference.
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I guess I'm wrong about it being obvious, [shrug].
Not necessarily, it’s just that to me the one doesn’t exclude the other in terms of possible options.
My suggestion is that the universe has always existed, and will always exist.
Heat death doesn’t exclude that possibility, it is just the form that that existence takes.
I just don't know where the heat escapes to unless you think the universe is finite and inflating.
The heat doesn’t escape anywhere, it just evens out and everything stops working. The idea was originally put forward in the late 1700s, well before any thoughts of expansion.