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Thread: Infinite

  1. #61
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    Quote Originally Posted by profloater View Post
    Infinitely far in the future has two assumptions, one that the future has meaning apart from our perception and two, that an infinite future means anything at all except as a limit to a model. It also has limits about light speed, at one reading infinitely far in the future must be very dark since no light has arrived. Or if you accept you can only mean a future at light speed, then have you reached the point at which you observe the big bang? Not really an infinity then?
    This is why personally I don't like to consider infinities in terms of any physical meaning, but if the universe does continue in extent infinitely in space & time, then there is clearly a "physical" consequence to consider. It's a bit like the centre of a black hole for example, where general relativity predicts a physical object that is infinitely dense and infinitely small. This is an absurd concept to imagine and makes no physical sense.

  2. #62
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    Quote Originally Posted by cosmocrazy View Post
    This is why personally I don't like to consider infinities in terms of any physical meaning, but if the universe does continue in extent infinitely in space & time, then there is clearly a "physical" consequence to consider. It's a bit like the centre of a black hole for example, where general relativity predicts a physical object that is infinitely dense and infinitely small. This is an absurd concept to imagine and makes no physical sense.
    Indeed, when we say our model breaks down in a black hole or in the big bang, it means a singularity of infinity or dividing by zero. We have a model where the universe can expand faster than light, so we have to wait for whatever light comes our way, as we do for the sun and all the stars anyway. If that model is correct, and it is mainstream, then we just cannot know about the “now” we experience in local life. Everything we experience is in the past. Yet infinity is really useful in calculus, it validates the small step assumptions we make in differentials, partial differentials and integrals . There is no physical dilemma if we remember our inconsistent maths is just a model that works for most of the time. There does not have to be real infinity. But personally, a model including infinity still seems more satisfactory than magical beginnings and endings.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  3. #63
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    Quote Originally Posted by profloater View Post
    Indeed, when we say our model breaks down in a black hole or in the big bang, it means a singularity of infinity or dividing by zero. We have a model where the universe can expand faster than light, so we have to wait for whatever light comes our way, as we do for the sun and all the stars anyway. If that model is correct, and it is mainstream, then we just cannot know about the “now” we experience in local life. Everything we experience is in the past. Yet infinity is really useful in calculus, it validates the small step assumptions we make in differentials, partial differentials and integrals . There is no physical dilemma if we remember our inconsistent maths is just a model that works for most of the time. There does not have to be real infinity. But personally, a model including infinity still seems more satisfactory than magical beginnings and endings.
    There doesn't have to be real infinity but its not beyond the realms of possibility. There is no reason why space and time can not continue on for infinity even if there was what appears to be a beginning. The issue I have is to understand what this means from a physical perspective. Especially where we talk about space-time as a whole with possibility of an infinite number of events that extend an infinite distance in time and space.

    What does this really mean?

  4. #64
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    Quote Originally Posted by cosmocrazy View Post
    There doesn't have to be real infinity but its not beyond the realms of possibility. There is no reason why space and time can not continue on for infinity even if there was what appears to be a beginning. The issue I have is to understand what this means from a physical perspective. Especially where we talk about space-time as a whole with possibility of an infinite number of events that extend an infinite distance in time and space.

    What does this really mean?
    Remember reality is our model in our head and we cannot know what causes phenomena that we experience. So you can have a model including infinity of spacetime, untestable by definition, and no one can say you are wrong. Another person can have a model including an infinite deity, equally untestable, and we cannot say that is wrong either. Only a model that has an outer wall with stars stuck to it would be, in principle, testable by observation and visit. Mainstream model has a light speed limit where universe is expanding at light speed or faster. Untestable.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    Quote Originally Posted by profloater View Post
    Remember reality is our model in our head and we cannot know what causes phenomena that we experience. So you can have a model including infinity of spacetime, untestable by definition, and no one can say you are wrong. Another person can have a model including an infinite deity, equally untestable, and we cannot say that is wrong either. Only a model that has an outer wall with stars stuck to it would be, in principle, testable by observation and visit. Mainstream model has a light speed limit where universe is expanding at light speed or faster. Untestable.
    Absolutely, but it may go beyond our models and be intrinsic to the universe anyhow, we don't know and, as you say, can't test it. But as nice as it would be to know and understand, what really matters is everything that is causally connected to us.

    "Truth, well that depends on your point of view"

  6. #66
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    Quote Originally Posted by profloater View Post
    But personally, a model including infinity still seems more satisfactory than magical beginnings and endings.
    Well, I think the opposite about beginnings at least, everything had to start somewhere. Nothing magical about that. A timeline that has "always been" seems impossible to me.

    Either way, we can't find out the "real truth". Only what observation shows us. So we're limited in time (T=0 cutoff in the past, future hasn't happened yet and keeps surprising us anyway) and space (lightspeed limit of the Observable Universe).
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by Noclevername View Post
    Well, I think the opposite about beginnings at least, everything had to start somewhere. Nothing magical about that. A timeline that has "always been" seems impossible to me.
    I don’t see why “everything has to start somewhere.” Maybe the universe has a discrete beginning, maybe not, but I don’t see why one is more reasonable than the other. Maybe time is a property that has no boundaries or maybe it does.

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  8. #68
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    Quote Originally Posted by Noclevername View Post
    Either way, we can't find out the "real truth". Only what observation shows us. So we're limited in time (T=0 cutoff in the past, future hasn't happened yet and keeps surprising us anyway) and space (lightspeed limit of the Observable Universe).
    Oh, and there have been attempts to go past T=0. Basically, theoretical advances and some evidence might give an indication of something coming before. Nobody has come up with something that passes muster, but we canít rule out the possibility someone will eventually.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." ó Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

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    Quote Originally Posted by Van Rijn View Post
    Oh, and there have been attempts to go past T=0. Basically, theoretical advances and some evidence might give an indication of something coming before. Nobody has come up with something that passes muster, but we can’t rule out the possibility someone will eventually.
    There might always be something new and unforeseen, as I said future developments can catch us off guard. But right now, the sign says No Trespassing Beyond This Point.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  10. #70
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    Quote Originally Posted by Noclevername View Post
    Well, I think the opposite about beginnings at least, everything had to start somewhere. Nothing magical about that. A timeline that has "always been" seems impossible to me.

    Either way, we can't find out the "real truth". Only what observation shows us. So we're limited in time (T=0 cutoff in the past, future hasn't happened yet and keeps surprising us anyway) and space (lightspeed limit of the Observable Universe).
    Well there you have it. A magical beginning is for me, something out of nothing. A whole universe of pluses and minuses. But as you say you can take your pick, untestable. As for time, we may have to learn how flexible that is. It does run slower in a stronger gravity field. So going back to a condensed universe, it might have been running slower and slower, making the big bang a very slow expansion. It only seems fast to us now when we talk of milliseconds into the bang, what would that mean to an observer then?
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  11. #71
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    Quote Originally Posted by profloater View Post
    Well there you have it. A magical beginning is for me, something out of nothing. A whole universe of pluses and minuses. But as you say you can take your pick, untestable. As for time, we may have to learn how flexible that is. It does run slower in a stronger gravity field. So going back to a condensed universe, it might have been running slower and slower, making the big bang a very slow expansion. It only seems fast to us now when we talk of milliseconds into the bang, what would that mean to an observer then?
    It moves relatively slower in a G field. So in the local frame, a millisecond is a millisecond regardless. To an observer "back then" the passage of time would not be slow.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  12. #72
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    Quote Originally Posted by Noclevername View Post
    It moves relatively slower in a G field. So in the local frame, a millisecond is a millisecond regardless. To an observer "back then" the passage of time would not be slow.
    Ok but we talk about the first microseconds , the first milliseconds, and most people think those are today microseconds etc. And we are talking about the whole universe getting going, so singularity seems to be an undersatement. This is not an average black hole thing!

    Besides the point. I would prefer the bang came from a previous compression than a fresh start. It is just my problem with something out of nothing even if it is just positives and negatives in balance. If we could do that trick, boy what an engine we could make. If the big bang was just a pregnant pause, we could have the pregnant pause in a nozzle engine. But we donít want a universe starting up in our rocket.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  13. #73
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    Quote Originally Posted by profloater View Post
    Ok but we talk about the first microseconds , the first milliseconds, and most people think those are today microseconds etc.
    Well, they are. Time passes at the same rate when there's no "outside" events to compare it to, and the whole Universe was the same density, so experienced time at the same rate.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    Quote Originally Posted by profloater View Post
    Ok but we talk about the first microseconds , the first milliseconds, and most people think those are today microseconds etc. And we are talking about the whole universe getting going, so singularity seems to be an undersatement. This is not an average black hole thing!
    It’s the opposite. Time has slowed down dramatically. What was a nanosecond then, now takes billions of years, that’s how slowly things are happening now.

    You just don’t notice how slow things are now, because all physical processes, including those involved in your perception, have slowed down.
    You have meddled with the primal forces of nature, and I won't have it!

  15. #75
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    Quote Originally Posted by 21st Century Schizoid Man View Post
    It’s the opposite. Time has slowed down dramatically. What was a nanosecond then, now takes billions of years, that’s how slowly things are happening now.

    You just don’t notice how slow things are now, because all physical processes, including those involved in your perception, have slowed down.
    Ok, it still distorts our visualisation.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  16. #76
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    Quote Originally Posted by profloater View Post
    Ok, it still distorts our visualisation.
    OK, assume that's true.

    Physics and cosmology are often counter-intuitive. We "expect" nature to conform to what we think should happen, and it sometimes disappoints us. That's why we have science, to correct our misapprehensions and model what's happening more accurately than imagination alone.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  17. #77
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    Quote Originally Posted by Noclevername View Post
    OK, assume that's true.

    Physics and cosmology are often counter-intuitive. We "expect" nature to conform to what we think should happen, and it sometimes disappoints us. That's why we have science, to correct our misapprehensions and model what's happening more accurately than imagination alone.
    I am not sure what you mean but it is not our normal experience that time slows. However it actually slows in a concentrated spacetime field near a big mass. So a new universe just popping into existence should actually slow time down quite a lot, as observed from here. If there was a t=0 it was a slow start. Infinitely slow? Not sure what the model says, normally the model breaks down at the interesting moment.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  18. #78
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    Quote Originally Posted by profloater View Post
    So a new universe just popping into existence should actually slow time down quite a lot, as observed from here.
    bold mine

    What does this mean? Time slowing is relative to one's reference frame. If all the Universe had the same mass density it would not make sense to talk of time being "slower" since the passage of time is what determines slowness. The whole Universe would have the same reference frame. Time then would be consistent with our own sense of time now.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  19. #79
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    Quote Originally Posted by Noclevername View Post
    bold mine

    What does this mean? Time slowing is relative to one's reference frame. If all the Universe had the same mass density it would not make sense to talk of time being "slower" since the passage of time is what determines slowness. The whole Universe would have the same reference frame. Time then would be consistent with our own sense of time now.
    I am hinting at the moment of the bang as singularity since this is an infinity thread. The relativity model does not apply in a singularity. Maybe the whole big bang is too big a subject for just a simple infinity.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  20. #80
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    Quote Originally Posted by profloater View Post
    I am hinting at the moment of the bang as singularity since this is an infinity thread. The relativity model does not apply in a singularity. Maybe the whole big bang is too big a subject for just a simple infinity.
    The "moment of the bang" is not covered by BBT because it's outside of what we can model. BBT starts with an existing Universe, not its origin.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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