Page 1 of 3 123 LastLast
Results 1 to 30 of 71

Thread: Question about time...

  1. #1
    Join Date
    Jun 2004
    Location
    Lugano, Switzerland
    Posts
    6,878

    Question about time...

    I know I am probably opening a can of worms here, but I have a rather simplistic question which has bugged me since childhood.

    The old model of the universe was that the universe always existed, will always exist for eternity. Problem here, I never could understand how we could ever reach the present, since the past was eternally long.

    Then the theory of the Big Bang showed up, and the question was what was before t=0? How could it start up?

    Now we speak of multiverses, bubble universes, branes colliding to create the Big Bang for our universe, etc. So these extend back infinitely (back to square one)

    So the question is: how could we ever have reached the (elusive, constantly changing) present if the past is infinite?

  2. #2
    Join Date
    Mar 2008
    Posts
    5,333
    I wouldn't say there is anything simplistic about the question, its rather a difficult one to answer, since we don't really know. The model of the big bang suggests that there was "nothing" before the start of the universe we observe today. That doesn't mean that it is certain there was nothing. "How could it start up?" a question that I mull over a lot myself. I think we are so accustomed to cause and effect it's difficult for us to conceptualise a situation where something could just happen from nothing, not even time.


    If the universe always existed, what do we mean by the "universe". The observational evidence strongly suggests that the universe we live in had a beginning and quite possibly will have an end. But is what we observe just a spec in an infinite ocean of universe/s? we don't know, and might never know.


    I think when we try to conceptualise infinity, especially infinite time, it raises questions about what time really is, what it means. Why is there an arrow of time? or is this just a point of view? We experience/measure time to follow a direction at a constant rate relative to our own frame of reference. But each frame of reference may experience/measure different rates of time relative to other frames. So if there is no universal time frame reference then this takes us right back to the question of what does this mean for time regarding the "start" of the universe?

    For example, a photon of light experiences no time or space. Therefore for the photon does the universe exist yet? Is there a start or an end?
    Last edited by cosmocrazy; 2017-Dec-01 at 09:42 AM.

  3. #3
    Join Date
    Mar 2010
    Location
    United Kingdom
    Posts
    6,610
    Quote Originally Posted by cosmocrazy View Post
    The model of the big bang suggests that there was "nothing" before the start of the universe we observe today.
    No it does not. The model says that the observable universe expanded from a hot dense state a finite time ago. And that is all it says.

    Quote Originally Posted by cosmocrazy View Post
    For example, a photon of light experiences no time or space. Therefore for the photon does the universe exist yet? Is there a start or an end?
    This is an extrapolation of SR concepts into an invalid domain.

  4. #4
    Join Date
    Jun 2004
    Location
    Lugano, Switzerland
    Posts
    6,878
    Our physics breaks down as we approach t=0 for the start of the big bang. Steven Weinberg in his book, "The First Three Minutes" uses this as a starting point, since going back closer is not possible, it leads to a singularity and infinity in our current theories.

  5. #5
    Join Date
    Jun 2002
    Posts
    32
    I think the theory "How to get from an infinite past to the present" is not a problem. It's just like a variable t which could be any negative value, or zero, or any positive value - it doesn't "get from there to here", it just is.

    Problems would be practical problems: If stars use up their hydrogen in fusion, then all across the universe there'd be less and less hydrogen compared to other elements over time. But right now we observe there's still plenty of it, so the fusion couldn't have started an infinite time ago.

  6. #6
    Join Date
    Jun 2004
    Location
    Lugano, Switzerland
    Posts
    6,878
    Quote Originally Posted by FrankWSchmidt View Post
    I think the theory "How to get from an infinite past to the present" is not a problem. It's just like a variable t which could be any negative value, or zero, or any positive value - it doesn't "get from there to here", it just is.

    Problems would be practical problems: If stars use up their hydrogen in fusion, then all across the universe there'd be less and less hydrogen compared to other elements over time. But right now we observe there's still plenty of it, so the fusion couldn't have started an infinite time ago.
    Except we are not talking about abstract mathematics. Saying it just is, I do not find satisfying...

  7. #7
    Join Date
    Apr 2011
    Location
    Norfolk UK and some of me is in Northern France
    Posts
    7,126
    Quote Originally Posted by gzhpcu View Post
    Except we are not talking about abstract mathematics. Saying it just is, I do not find satisfying...
    yes but the whole idea is based on a maths model isn't it? You cannot expect to get a feel for time in that model of the distant past if you don't believe the maths as a backwards prediction model. Most of what we have to work on is observation of stars using the electromagnetic spectrum and then maths to form a model of how they got there. Then we add particle work here on Earth but it's mostly looking at stars and maths.
    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

  8. #8
    Join Date
    Oct 2009
    Location
    a long way away
    Posts
    9,989
    I can't really see a problem. There are an infinite number of integers, but 5 still exists. And the universe might be spatially infinite, but we are still "here". We didn't have to get here from an infinite distance away.

  9. #9
    Join Date
    Jun 2004
    Location
    Lugano, Switzerland
    Posts
    6,878
    Quote Originally Posted by profloater View Post
    yes but the whole idea is based on a maths model isn't it? You cannot expect to get a feel for time in that model of the distant past if you don't believe the maths as a backwards prediction model. Most of what we have to work on is observation of stars using the electromagnetic spectrum and then maths to form a model of how they got there. Then we add particle work here on Earth but it's mostly looking at stars and maths.
    Math does not help me. I am talking about existence, not abstract symbolisms created by the mind.

  10. #10
    Join Date
    Oct 2005
    Posts
    25,700
    The way I would put it is, time is not a thing, it is a concept that we have developed because it has worked for us. This does not imply it must always work for us in every situation-- there may be situations in which we need to replace the notion with something else. This always happens, it's how science advances. So we have two ways to frame questions like:
    1) What existed before the beginning of time?
    or
    2) When time has a beginning, can it be the same time that we normally think of, or do we need a new concept there?
    I rather feel the second question is the one more likely to bear scientific fruit, but of course experimental verification is quite tricky in this area!

    Just as an example of the kind of thing I'm talking about, relativity already forced us to radically change our concept of time. We used to think time was universal, ticking along for all things in the universe just the same way. That turns out to be completely wrong when objects pass each other at speeds near c. Instead, each object has its own proper time. However, in the very early universe when the energy scales were ghastly large, there were not "things" that could survive, they were constantly appearing and disappearing, destroyed in timescales shorter than what we would normally regard as a tick of a clock. So if there are no things that could have a proper time, then there is not proper time, the whole notion essentially dissipates. And of course photons don't have proper time in the first place. So a Big Bang model that invokes an initial singularity (which you need to be able to talk about "before" the "beginning") already invokes an invalid use of the time concept at that singularity, just by virtue of how fast the particles are moving and how shortlived they are-- even when we stick to the concept of time that has been found to work in high-energy experiments. One might even be tempted to conclude that in the limit as all particles are highly relativistic, the clocks we can imagine for them all cease to tick-- so we have a "beginning" to time right there, it is born from a state of extreme time dilation, almost like the proverbial caveman coming out of deep freeze.
    Last edited by Ken G; 2017-Dec-01 at 03:40 PM.

  11. #11
    Join Date
    Oct 2009
    Location
    a long way away
    Posts
    9,989
    Maybe if you don't think of time as something that "flows" or something we move through, but just as a set of coordinates then it is no more problematical that were are "now" than that we are "here". Neither requires us to have come from an infinite distance.

  12. #12
    Join Date
    May 2005
    Posts
    7,713
    Quote Originally Posted by Strange View Post
    I can't really see a problem. There are an infinite number of integers, but 5 still exists. And the universe might be spatially infinite, but we are still "here". We didn't have to get here from an infinite distance away.
    An infinite number of integers in both directions, too

    Quote Originally Posted by gzhpcu View Post
    Math does not help me. I am talking about existence, not abstract symbolisms created by the mind.
    But, if you can abstractly manage the mathematical example, doesn't it give you a good handle on the actual?

  13. #13
    Join Date
    Jun 2004
    Location
    Lugano, Switzerland
    Posts
    6,878
    Theories apart, subjectively, time passes for me. I remember yesterday, when I graduated, when I went to elementary school... a chain of events. That is what I am alluding to. Not mathematical concepts.

  14. #14
    Join Date
    Oct 2009
    Location
    a long way away
    Posts
    9,989
    Quote Originally Posted by gzhpcu View Post
    Theories apart, subjectively, time passes for me. I remember yesterday, when I graduated, when I went to elementary school... a chain of events. That is what I am alluding to. Not mathematical concepts.
    You can start from "now" and work back as far as you like. You didn't have to start from infinity to get here though.

  15. #15
    Join Date
    Apr 2011
    Location
    Norfolk UK and some of me is in Northern France
    Posts
    7,126
    Quote Originally Posted by gzhpcu View Post
    Theories apart, subjectively, time passes for me. I remember yesterday, when I graduated, when I went to elementary school... a chain of events. That is what I am alluding to. Not mathematical concepts.
    Do you find memories have time and date attached to them or do you have milestones like you know the year you graduated as a separate fact? Some people do seem to have tagged memories, others are ordered by intensity with no strong sense of how long ago or indeed sequence. A chain of events as a chronicle has no intergral evidence attached until we allocate cause and effect with time, that every effect has to have an earlier cause. This simple idea breaks down if you ask about a beginning.
    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. #16
    Join Date
    Oct 2005
    Posts
    25,700
    Quote Originally Posted by gzhpcu View Post
    Theories apart, subjectively, time passes for me. I remember yesterday, when I graduated, when I went to elementary school... a chain of events. That is what I am alluding to. Not mathematical concepts.
    You just described a concept. Are you saying it only counts as such if it is not mathematical? Besides, what I said applies equally to the description you just gave-- none of those things you said would make any sense at the beginning of the universe, so your own concept of time doesn't make sense there either, nor does the experimentally verified one.

    Look more closely at your logic here. You are saying that you have found the concept of a "chain of events," pieced together using a mental capacity you call memory, is a useful way to build a concept of time. That is certainly true, we've all found that to be the case. But we build our concepts based on what works, just as you did here, we don't tell the universe what has to make sense first, and then require that it must obey. That isn't what you did when you built the concept you just described, so it is also what you should not do when you talk about the evidence that the universe had a beginning, or a singularity, or just a period of extreme difference from now, however you like to look at it.

    The key point I'm making here is that, over and over in the history of science, we have found that our own experiences, those we use to get a sense of "what is" on an everyday basis, sample an extremely tiny corner of what actually is, even if you hold that the concept of "what actually is" makes sense independently of what we can experience and how we can make sense of that. As such, in science we constantly find that we need to update "what is" when our awareness extends to new spheres well outside common experience. You have a tendency to discount everything that is not in your common experience, labeling it as "mathematical" in nature, but why would you think that your own tiny corner of experience has some kind of monopoly on how reality works? It seems to me that one of the first steps of science is to adopt a stance of not knowing, rather than a stance of pre-knowing. You didn't pre-know anything when you were born into this world, why start now?

    Don't get me wrong, I agree that saying it took an infinite time to "get here" is a problematic notion, I don't think that would have ever been a working concept of time. But neither should we expect our everyday notion to apply universally. We always need to be ready to throw out a model, any model no matter how fundamental, when we reach the domain where it just doesn't make sense any more, or is found to disagree with observations, or where we cannot even provide operational definitions for what we are talking about. That's if we will use science as our tool, and no sharper one exists.
    Last edited by Ken G; 2017-Dec-01 at 04:45 PM.

  17. #17
    Join Date
    Jun 2004
    Location
    Lugano, Switzerland
    Posts
    6,878
    Quote Originally Posted by profloater View Post
    Do you find memories have time and date attached to them or do you have milestones like you know the year you graduated as a separate fact? Some people do seem to have tagged memories, others are ordered by intensity with no strong sense of how long ago or indeed sequence. A chain of events as a chronicle has no intergral evidence attached until we allocate cause and effect with time, that every effect has to have an earlier cause. This simple idea breaks down if you ask about a beginning.
    Look: my grandparents were born, my parents were born, I was born. A clear sequence.

  18. #18
    Join Date
    Jun 2004
    Location
    Lugano, Switzerland
    Posts
    6,878
    Quote Originally Posted by Ken G View Post
    You just described a concept. Are you saying it only counts as such if it is not mathematical? Besides, what I said applies equally to the description you just gave-- none of those things you said would make any sense at the beginning of the universe, so your own concept of time doesn't make sense there either, nor does the experimentally verified one.
    I am speaking from my point of view. From what I experience. Things which have a time sequence in my life. I am saying I do not need math for this simple example.

    Quote Originally Posted by Ken G View Post
    Look more closely at your logic here. You are saying that you have found the concept of a "chain of events," pieced together using a mental capacity you call memory, is a useful way to build a concept of time. That is certainly true, we've all found that to be the case. But we build our concepts based on what works, just as you did here, we don't tell the universe what has to make sense first, and then require that it must obey. That isn't what you did when you built the concept you just described, so it is also what you should not do when you talk about the evidence that the universe had a beginning, or a singularity, or just a period of extreme difference from now, however you like to look at it.
    Are you questioning the red shift of galaxies, pointing towards the Big Bang?

    Quote Originally Posted by Ken G View Post
    The key point I'm making here is that, over and over in the history of science, we have found that our own experiences, those we use to get a sense of "what is" on an everyday basis, sample an extremely tiny corner of what actually is, even if you hold that the concept of "what actually is" makes sense independently of what we can experience and how we can make sense of that. As such, in science we constantly find that we need to update "what is" when our awareness extends to new spheres well outside common experience. You have a tendency to discount everything that is not in your common experience, labeling it as "mathematical" in nature, but why would you think that your own tiny corner of experience has some kind of monopoly on how reality works? It seems to me that one of the first steps of science is to adopt a stance of not knowing, rather than a stance of pre-knowing. You didn't pre-know anything when you were born into this world, why start now?
    I naturally assume when I am looking at my wristwatch observing that the second hand is moving that time is passing for me. When I look at the moon and see it moving during the night, I assume time is passing. I go play tennis: I toss the ball in the air and hit a serve. Time passing. I learned all this as I grew up. I had no pre-knowledge. It is experience.

    Quote Originally Posted by Ken G View Post
    Don't get me wrong, I agree that saying it took an infinite time to "get here" is a problematic notion, I don't think that would have ever been a working concept of time. But neither should we expect our everyday notion to apply universally. We always need to be ready to throw out a model, any model no matter how fundamental, when we reach the domain where it just doesn't make sense any more, or is found to disagree with observations, or where we cannot even provide operational definitions for what we are talking about. That's if we will use science as our tool, and no sharper one exists.
    If everything I observe and experience, reinforces my concept of time, then I will grow to accept it. Quite obviously, I am talking about our macro world.

    Stephen Hawking posited three arrows of time:
    1) psychological time: things we remember are in the past.
    2) Entropic time: universe moves from a state of order to a state of disorder.
    3) cosmological time: arrow of time moves forward in inflationary state

    He argued that the first two are the same: To create memories neurons align themselves in a certain way. This requires energy, which results in our body heating up a little bit, which means total entropy increases. Our memory only increases when entropy increases. So the two arrows must point in the same direction.

    He argued that these two notions are the same.


  19. #19
    Join Date
    Apr 2011
    Location
    Norfolk UK and some of me is in Northern France
    Posts
    7,126
    Quote Originally Posted by gzhpcu View Post
    I know I am probably opening a can of worms here, but I have a rather simplistic question which has bugged me since childhood.

    The old model of the universe was that the universe always existed, will always exist for eternity. Problem here, I never could understand how we could ever reach the present, since the past was eternally long.

    Then the theory of the Big Bang showed up, and the question was what was before t=0? How could it start up?

    Now we speak of multiverses, bubble universes, branes colliding to create the Big Bang for our universe, etc. So these extend back infinitely (back to square one)

    So the question is: how could we ever have reached the (elusive, constantly changing) present if the past is infinite?
    I suppose you are thinking of infinity as a number too big to think about. When I was younger I always though infinity of the past was more satisfactory than a beginning. So when the Big Bang was proposed I preferred to see that as a stage, a node if you like. If you think of a solar system it could be timeless cycling around for ever or it could be evolving out of dust, but the whole universe is a big thing to arrive out of nothing, but that is not what the current model says. The BB is a singularity in the maths or a point beyond which we cannot see backwards.
    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. #20
    Join Date
    May 2005
    Posts
    7,713
    Quote Originally Posted by gzhpcu View Post
    I am speaking from my point of view. From what I experience. Things which have a time sequence in my life. I am saying I do not need math for this simple example.
    Need math? Math is just a tool that can aid in understanding. It's a powerful tool, too, if you reject it you're just limiting your understanding.
    Stephen Hawking posited three arrows of time:
    1) psychological time: things we remember are in the past.
    2) Entropic time: universe moves from a state of order to a state of disorder.
    3) cosmological time: arrow of time moves forward in inflationary state

    He argued that the first two are the same: To create memories neurons align themselves in a certain way. This requires energy, which results in our body heating up a little bit, which means total entropy increases. Our memory only increases when entropy increases. So the two arrows must point in the same direction.

    He argued that these two notions are the same.
    Of course they're the same by that description. The second is a physical law, the first is described by a physical process. If it is a physical process, which I have no reason to doubt right now.

  21. #21
    Join Date
    Jun 2004
    Location
    Lugano, Switzerland
    Posts
    6,878
    Quote Originally Posted by grapes View Post
    Need math? Math is just a tool that can aid in understanding. It's a powerful tool, too, if you reject it you're just limiting your understanding.

    Of course they're the same by that description. The second is a physical law, the first is described by a physical process. If it is a physical process, which I have no reason to doubt right now.
    Guess I did not make myself clear. I just said that I do not math in this instance, i.e., sequencing my memories...

  22. #22
    Join Date
    Mar 2004
    Posts
    15,779
    Executive summary: Everything has a beginning -- unless it doesn't.
    0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 ...
    Skepticism enables us to distinguish fancy from fact, to test our speculations. --Carl Sagan

  23. #23
    Join Date
    Aug 2005
    Location
    location
    Posts
    12,410
    Anchor points. Even if time and space are infinite, anchor points give us both an orientation and a reference for reckoning. Unless one posits that time is infinitely indivisible (i.e. Zeno's Paradox) in such a way that there is no fixed scale from moment to moment (ignoring Planck Time), time can still be counted at a rate of 1 second per second. Just because something is infinite, doesn't mean it's infinitesimal. For all we know, it's not infinite, but merely looks that way.

    Think of it as a treadmill. You see the belt rotate over the front roller, and if you look behind, you can see it disappear over the rear roller, and if you see markings on the belt, you can discern both sequence and rate. However, you may not know how long the belt is. It could be a simple loop that connects back to the front roller using the shortest path possible, or it could be many yards longer, supported by more wheels and motors that allow it to support its movement. It could have loops and rollers that are much larger and much smaller, allowing the speed to appear faster or slower to other entities on that part of the treadmill, but you don't know about that since you can't see it. All you see is the treadmill between the rollers in front of and behind you, and its rate. For all you know, the markings are painted on just before it comes into view and erased as soon as it disappears, but that doesn't make it any less real, to you at least.

    Or think of it as industrial baking. If you've ever watched "How It's Made," you'll understand. A dough mixing machine pours a continuously made dough onto a conveyor. It goes under various hoppers, and gets stuff added to it. Then it goes through a cutter, is baked, and is then cooled and packaged. To someone at a certain point on the conveyor, it looks like the dough is never ending. However, when we look at the bigger picture, we realize it's being part of a cycle that is discrete and non-infinite.
    Et tu BAUT? Quantum mutatus ab illo.

  24. #24
    Join Date
    Oct 2005
    Posts
    25,700
    Quote Originally Posted by gzhpcu View Post
    Are you questioning the red shift of galaxies, pointing towards the Big Bang?
    Quite the opposite, I'm describing the logical ramifications of those redshifts.
    I naturally assume when I am looking at my wristwatch observing that the second hand is moving that time is passing for me.
    I know, that's what I said.
    When I look at the moon and see it moving during the night, I assume time is passing. I go play tennis: I toss the ball in the air and hit a serve. Time passing. I learned all this as I grew up. I had no pre-knowledge. It is experience.
    That's all what I just said, read it again. Here is what you are doing. You have all the experiences you just named, and you built a concept of time from them. None of them occurred anywhere near the beginning of the universe, and among many other things, none of them hold a candle to the extreme energy scales of those early times (based on interpretation of galactic redshifts). In particular, as I said, there were no objects we have ever observed that existed for a "proper time" long enough to rise to the level of what you call "existence" when you are talking about moons and tennis balls. What's more, you had no "pre-knowledge" of moons or tennis balls when you were born, you built that knowledge from experience. But then, you take your construction, and you extrapolate it into realms you have not experienced, yet you are surprised when your constructions seem to fail you. I'm saying you should never find that experience particularly surprising-- that's what you have experienced your whole life, a need to rebuild your concepts when exposed to a whole new set of situations. This is also what physics had to do, when it discovered that the Earth is not the only thing that is responsible for gravity, when it discovered that motion does not need a cause to continue in friction-free environments, when it discovered that particles and waves share similar rules of behavior, and when it discovered that time does not tick along universally for all objects-- but instead every object has its own time, if indeed it exists long enough to support a notion of the passage of time for that object. The question that the early moments of an energy density singularity force us to ask is, how long must a particle exist before we can apply a concept of the passage of proper time to that particle? And when every particle has a different proper time, does anything you've ever experienced in your life, that contributed to your concept of time, apply at all?
    Quite obviously, I am talking about our macro world.
    But that's just it, you're not talking about our macro world. Look back at your OP, and notice that you asked a question that involves t=0, so why do you think that is about our macro world?
    Stephen Hawking posited three arrows of time:
    1) psychological time: things we remember are in the past.
    2) Entropic time: universe moves from a state of order to a state of disorder.
    3) cosmological time: arrow of time moves forward in inflationary state
    Ah, but that is quite a bit more than just three arrows of time, those are three very different types of time! In particular, they are not at all the same thing. The first is a mental construct that is not measured with a clock at all. The second applies to large systems that can support a concept of proper time for the whole system, like a functioning timepiece, which of course is quite a bit different from the elapsed proper time of all the components of that system (like people, if the system is a universe). The third engenders a set of operational definitions that cobble together a host of different reference frames into a mathematical entity called the "comoving frame" in cosmology. Above all, it seems quite likely that all three of those concepts of time lose their operational support as one approaches t=0.
    He argued that the first two are the same: To create memories neurons align themselves in a certain way. This requires energy, which results in our body heating up a little bit, which means total entropy increases. Our memory only increases when entropy increases. So the two arrows must point in the same direction.

    Now, the important thing is that all three of those "types" of time play well together in the context of our own experiences, so we suffer no existential angst around the issue of "which is the real time." But we don't have to stress these notions very far before disconnects do appear, and we find they cannot all be the same. The natural conclusion is that none of them are the "actual thing that time is," they are all just useful mental constructs that we call "time", analogous to all the useful mental constructs we call "a computer" or "a phone," or any of the other countless useful constructs we invoke every day that are not "the actual thing that a computer is" or "the actual thing that a phone is."
    He argued that the first two are the same: To create memories neurons align themselves in a certain way. This requires energy, which results in our body heating up a little bit, which means total entropy increases. Our memory only increases when entropy increases. So the two arrows must point in the same direction.
    Yes, the arrows are the same, but the times are not. The arrow is a tiny component of the concept of time.
    He argued that these two notions are the same.
    I doubt he argued the notions are the same, because it is very easy to find counterexamples. If you've ever heard the expression "time flies when you're having fun," that's an obvious counterexample to the claim that the notion of psychological time is the same as the notion of entropic time.

  25. #25
    Join Date
    Oct 2005
    Posts
    25,700
    Quote Originally Posted by 01101001 View Post
    Executive summary: Everything has a beginning -- unless it doesn't.
    Or put this way: the concept of a beginning is a useful notion for everything-- except when it isn't. What's more, sometimes sticking too literally to that notion actually becomes a barrier to understanding. I can ask anyone-- when did you begin? Is finding a literal answer to that question useful to your understanding of yourself, or an impediment to it?

  26. #26
    Join Date
    Jan 2002
    Location
    The Valley of the Sun
    Posts
    8,820
    We don't know that there was a beginning of the universe. Maybe the diameter of the universe was a Planck length 1 second before the the Big Bang, of a Planck length a second before that, ⅛ of a Planck length a second before that, etc. Then it would have been doubling in diameter every second until it got big enough for us to theorize about. Since for each second before that it would have been half the size that it was a second later, there would have never been a time when its diameter was zero. There need not have been a beginning.

    I think there's a problem with the universe being infinitely old only if it had a beginning. Then infinite time would have had to have passed between two events, the beginning and now. We would never have gotten to this point in time. But if there was no beginning then only finite time would have to have passed between any two events. Just like on a number line with infinite numbers, the difference between any two numbers is finite.

  27. #27
    Join Date
    Jun 2004
    Location
    Lugano, Switzerland
    Posts
    6,878
    Or maybe to put it another way: how can I get to the present from the past?

  28. #28
    Join Date
    Oct 2005
    Posts
    25,700
    Indeed, how do you know you are "in" the present in the first place? How much time is in a "now", such that you could have "gotten there" in some perceptual sense? If you say that "now" is an instant, then it's pretty clear "you" aren't there, as "you" don't do anything in an instant. Or if you say "now" is whatever period of time it takes for you to formulate the concept you call "now", then one "now" cannot "turn into" another, as there are no lines drawn in those shifting sands, flowing through the hourglass. These concepts are always much more vague than we tend to admit to ourselves, but they work for us-- as long as we don't take them too literally.

  29. #29
    Join Date
    Jun 2004
    Location
    Lugano, Switzerland
    Posts
    6,878
    The present is a moving target. It is like frames of a motion picture. Now is dynamic. I can not freeze the present, the clock moves constantly. The present is what I am currently experiencing. But in terms of the universe, I could approximate it and say it is today, using our calendar as a reference point. One rotation of our planet.

  30. #30
    Join Date
    May 2008
    Location
    The Netherlands
    Posts
    14,204
    Quote Originally Posted by gzhpcu View Post
    The present is a moving target. It is like frames of a motion picture. Now is dynamic.
    Not to a photon, at c. So why should time adhere to your description or our perception when we reach another limit, where t reaches zero and speed might cease to have meaning?

    Quote Originally Posted by Ken G View Post
    If you've ever heard the expression "time flies when you're having fun," [...]
    I heard it as "times are fun when you're having flies", but the one expressing it was a bit green.
    ____________
    "Dumb all over, a little ugly on the side." -- Frank Zappa
    "Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
    "This is really very simple, but unfortunately it's very complicated." -- publius

    Moderator comments in this color | Get moderator attention using the lower left icon:
    Recommended reading: Forum Rules * Forum FAQs * Conspiracy Theory Advice * Alternate Theory Advocates Advice

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •