4 ms·

Physicist here. Although I am not really a "cosmologist," I have studied cosmology, and have spent a lot of time pondering the the big bang because I think it i

Physicist here. Although I am not really a "cosmologist," I have studied cosmology, and have spent a lot of time pondering the the big bang because I think it is interesting, and because so many people like you misunderstand it. The universe did not come from nothing. Consider the following two claims: * The universe has a finite age. * The universe has always existed. Both of these claims are true. It might seem that if something has always existed, it must have existed for infinitely long. No so. At every time in history, the universe has existed, even though the age is finite. Your intuition might disagree. But recognize your intuition has been developed under very peculiar circumstances on the surface of the Earth. You should be skeptical of your own intuition when studying things outside of your usual experience. In this case, human intuition says two things: * There was always something before. * There was always something 5 minutes before. In ordinary human life, both claims are true. That's what your intuition says. But for the universe as a whole, only the first claim is true, and the second claim is false. Even though it is true that there was always something "before" (for any time you give me, I can divide that time in two and give you an earlier time), it is nevertheless not true that there was always something 5 minutes before (pick 4 minutes after the big bang, and 5 minutes earlier than that is simply undefined [1]). Big Bang theory is a self-consistent, meaningful mathematical theory. It does not fly in the face of logical reasoning. Rather, it is a spectacular case-in-point of the power of logical reasoning to describe and explain the universe. Your second point is that the Big Bang disobeys the first law of thermodynamics, which is the conservation of energy. False. You are assuming there was a period of time when there was no energy, and then suddenly energy came into being. That's not what happened. The energy has always been around, for all time, and thus the first law is not violated. [1] It so happens that "negative time", or even time t=0, is equally as meaningless as Elephant Time or Verb Time. They are all undefined.

itistoday 16y ago
I understand perfectly well your point of view, you don't need to lecture me on it, I've heard it many times before, as I alluded previously. The universe did not come from nothing. Consider the following two claims: * The universe has a finite age. * The universe has always existed. Both of these claims are true. This is a perfect example of the reasoning I described, thank you. Here's the other bit: [1] It so happens that "negative time", or even time t=0, is equally as meaningless as Elephant Time or Verb Time. They are all undefined. I understand this concoction you've formulated, but it isn't very convincing. There's absolutely no evidence that this interpretation of the word "always" is true, and further, it's a violation of Occam's Razor. It would be simpler to take "always" literally, but you are in fact, through what amounts to simple verbal trickery, changing its meaning. You can state it's "meaningless" to speak of t=0, but you provide zero backup for this, other than it satisfies your fantasy. You can state it's "meaningless" to ask what happened X minutes before the Big Bang, but again, this is only in the service of satisfying your fantastical theory. Meanwhile, back in the Universe and the realm of Logic, it's very meaningful to ask what happened at "t=0", because such a state did exist. It even existed in your Big Bang Theory, which states there was an "initial state." It is highly improbable (if not provably impossible), that such an "initial state" is realistically feasible, and it certainly violates Occam's Razor. Your "initial state" has no explanation. You in fact vehemently object to any attempts at an explanation, deriding them as "undefined." This is faith in its purest form. Sorry, but I think you are a very religious man and don't realize it. Thank you, however, for the wonderful illustration of my point, I can use it as a historical example of the problem. :-)
- itistoday 16y ago
  To those downvoting me, you're welcome to speak up. This is a game of logic, and I was hoping that this community could keep the religious knee-jerk reactions down to a minimum. :-\
  - yafujifide 16y ago
    FWIW, I did not downvote you. But you still do not seem to comprehend the fact that the standard theory assumes time is finite. In order to disprove such a theory, you cannot just assume that time is infinite, because you are assuming the conclusion. If you convince me that you actually understand this, I will continue responding to you.
    - itistoday 16y ago
      FWIW, I did not downvote you. I know, HN doesn't allow downvoting of responses. :-p But you still do not seem to comprehend the fact that the standard theory assumes time is finite. Really? I thought I was very clear in demonstrating that I understood this through and through, hence the accusation of faith. I did not simply use an assumption that time is infinite as disproof, in fact I did not disprove BBT at all in my response, but merely gave reasons why I thought it was extremely unlikely to have a start.
      - jmathes 16y ago
        You sound like a crackpot. You don't sound like you understand physics. You also sound cranky. If you want to have a discussion, you should stop using grandiose language.
  - deleted 16y ago
    [deleted]
  - tlholaday 16y ago
    itistoday, do you agree that atomic clocks appear to run more slowly as the gravitational field gets stronger?
joshuacc 16y ago
"It so happens that "negative time", or even time t=0, is equally as meaningless as Elephant Time or Verb Time. They are all undefined." I'm very curious about the assertion that t=0 is meaningless. Is this the conclusion of a line of reasoning, or is it an axiom assumed in order to make the theory work? It looks like the latter to me, but that may just be because I'm not familiar with the literature and concepts.
- yafujifide 16y ago
  In the standard theory, t=0 is a "singularity." Energy density becomes infinite, for example, at t=0. What that really means is that t=0 is undefined in the same sense that 1/0 is undefined. Consider the function 1/x. For all positive x, 1/x is defined. As you approach x=0 from the right, 1/x approaches infinity. Same thing for the density of the universe. But the point 1/0 itself is undefined, even though the limit is well defined from the right. Likewise, t=0 itself is undefined, even though the density is well defined for all times greater than t=0. I wouldn't really consider this an "assumption." It is actually a consequence of assuming that the universe is expanding in accordance with the law of gravity and that energy is conserved. The only way to do it is to construct a "metric" ( http://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre%E2%80%93Robertson%E2%80%93Walker_metric http://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre... ) where a bunch of parameters are undefined at t=0, but well-defined thereafter.
  - joshuacc 16y ago
    Thanks for the explanation. I think part of my confusion arises from the (apparently) mistaken idea that t=0 is equivalent to "the first moment of time." But it looks like t=0 is closer to "before the first moment of time". In a certain sense, that's a contradiction, because you can't have "before" time, but in another sense it's the only way to speak of that which (logically, not necessarily chronologically) precedes time. Would you say that's a decent summary, given that I'm translating from scientific terms to more philosophical terms?
    - yafujifide 16y ago
hugh3 16y ago
It so happens that "negative time", or even time t=0, is equally as meaningless as Elephant Time or Verb Time. They are all undefined But Hammer Time is still okay, right?

itistoday 16y ago

I understand perfectly well your point of view, you don't need to lecture me on it, I've heard it many times before, as I alluded previously. The universe did not come from nothing. Consider the following two claims: * The universe has a finite age. * The universe has always existed. Both of these claims are true. This is a perfect example of the reasoning I described, thank you. Here's the other bit: [1] It so happens that "negative time", or even time t=0, is equally as meaningless as Elephant Time or Verb Time. They are all undefined. I understand this concoction you've formulated, but it isn't very convincing. There's absolutely no evidence that this interpretation of the word "always" is true, and further, it's a violation of Occam's Razor. It would be simpler to take "always" literally, but you are in fact, through what amounts to simple verbal trickery, changing its meaning. You can state it's "meaningless" to speak of t=0, but you provide zero backup for this, other than it satisfies your fantasy. You can state it's "meaningless" to ask what happened X minutes before the Big Bang, but again, this is only in the service of satisfying your fantastical theory. Meanwhile, back in the Universe and the realm of Logic, it's very meaningful to ask what happened at "t=0", because such a state did exist. It even existed in your Big Bang Theory, which states there was an "initial state." It is highly improbable (if not provably impossible), that such an "initial state" is realistically feasible, and it certainly violates Occam's Razor. Your "initial state" has no explanation. You in fact vehemently object to any attempts at an explanation, deriding them as "undefined." This is faith in its purest form. Sorry, but I think you are a very religious man and don't realize it. Thank you, however, for the wonderful illustration of my point, I can use it as a historical example of the problem. :-)

itistoday 16y ago
To those downvoting me, you're welcome to speak up. This is a game of logic, and I was hoping that this community could keep the religious knee-jerk reactions down to a minimum. :-\
- yafujifide 16y ago
  FWIW, I did not downvote you. But you still do not seem to comprehend the fact that the standard theory assumes time is finite. In order to disprove such a theory, you cannot just assume that time is infinite, because you are assuming the conclusion. If you convince me that you actually understand this, I will continue responding to you.
  - itistoday 16y ago
    FWIW, I did not downvote you. I know, HN doesn't allow downvoting of responses. :-p But you still do not seem to comprehend the fact that the standard theory assumes time is finite. Really? I thought I was very clear in demonstrating that I understood this through and through, hence the accusation of faith. I did not simply use an assumption that time is infinite as disproof, in fact I did not disprove BBT at all in my response, but merely gave reasons why I thought it was extremely unlikely to have a start.
    - jmathes 16y ago
      You sound like a crackpot. You don't sound like you understand physics. You also sound cranky. If you want to have a discussion, you should stop using grandiose language.
- deleted 16y ago
  [deleted]
- tlholaday 16y ago
  itistoday, do you agree that atomic clocks appear to run more slowly as the gravitational field gets stronger?

joshuacc 16y ago

"It so happens that "negative time", or even time t=0, is equally as meaningless as Elephant Time or Verb Time. They are all undefined." I'm very curious about the assertion that t=0 is meaningless. Is this the conclusion of a line of reasoning, or is it an axiom assumed in order to make the theory work? It looks like the latter to me, but that may just be because I'm not familiar with the literature and concepts.

yafujifide 16y ago
In the standard theory, t=0 is a "singularity." Energy density becomes infinite, for example, at t=0. What that really means is that t=0 is undefined in the same sense that 1/0 is undefined. Consider the function 1/x. For all positive x, 1/x is defined. As you approach x=0 from the right, 1/x approaches infinity. Same thing for the density of the universe. But the point 1/0 itself is undefined, even though the limit is well defined from the right. Likewise, t=0 itself is undefined, even though the density is well defined for all times greater than t=0. I wouldn't really consider this an "assumption." It is actually a consequence of assuming that the universe is expanding in accordance with the law of gravity and that energy is conserved. The only way to do it is to construct a "metric" ( http://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre%E2%80%93Robertson%E2%80%93Walker_metric http://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre... ) where a bunch of parameters are undefined at t=0, but well-defined thereafter.
- joshuacc 16y ago
  Thanks for the explanation. I think part of my confusion arises from the (apparently) mistaken idea that t=0 is equivalent to "the first moment of time." But it looks like t=0 is closer to "before the first moment of time". In a certain sense, that's a contradiction, because you can't have "before" time, but in another sense it's the only way to speak of that which (logically, not necessarily chronologically) precedes time. Would you say that's a decent summary, given that I'm translating from scientific terms to more philosophical terms?
  - yafujifide 16y ago

hugh3 16y ago

It so happens that "negative time", or even time t=0, is equally as meaningless as Elephant Time or Verb Time. They are all undefined But Hammer Time is still okay, right?