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Issue with time's arrow

  1. Jan 5, 2014 #1
    Firstly, my apologies for my naivety in Physics. Mathematics is not my native language. I have an idea that I'm not sure how to express and unaware of it's validity. I would appreciate it if somebody better equipped could consider this proposition.
    I've heard that time's apparent onward march is anomalous, different to the function of every other known field. I was thinking that if time did feature polarity, which it may, is it possible that the distance that a particle could travel in both directions in time may be proportional to Planck's constant over 2∏? I'm wondering if an oscillation, or even super position, within this time range into the past and into the future could be considered as the present - blurry at the planck scale and perhaps accounting for quantum phenomenon involving time. Following this line of thought, could the quantum wave be involved somehow?

    I'm dreadfully sorry if this made no sense at all. I'm trying to understand the relationships between the interesting bits of the universe.
  2. jcsd
  3. Jan 5, 2014 #2


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    I don't think so, as the ability for a particle to travel through time, even if just small distances, would most likely result in weird things happening that violate known physics. Imagine the fusion of two hydrogen to form deuterium where one of the protons decides it wants to travel backwards in time to a point before the fusion event.
  4. Jan 5, 2014 #3


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    Thermodynamics suggest time is not symmetric, despite the fact the usual equations for physical processes appear to work equally well forward or backwards in time. One thing I find fascinating is muon decay, which is not very well behaved.
  5. Jan 6, 2014 #4


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    I don't know if I would use the word anomalous. But the arrow of time is certainly a different sort of thing than a field.

    Certainly at the microscopic level all of our natural laws obey time symmetry (technically, CPT symmetry, but that's neither here nor there). The existence of an arrow of time is found nowhere in any natural laws that we have discovered. Instead, it appears to be a phenomenon intimately tied to entropy.

    Think, for a moment, how you can tell if a video is being played forward or backward. Sometimes you can tell by knowing how the entities in the video usually behave (e.g. cars usually drive forward, people usually walk forward). But that can be fooled. What can't be fooled is an event like jumping into a pool, breaking an egg, or shattering a glass. What these events have in common is an increase in entropy. We know when such a video is being played forwards or backwards, because it's just not possible, for example, for a bunch of shards of glass to jump together to form a whole glass (well, technically it's possible, it would just require looking at shards of glass for much longer than the current age of the universe to have a reasonable chance of seeing such an event). But it's very, very easy to go from a low entropy state (a whole glass) to a high entropy state (a bunch of shards of glass on the floor).

    There's nothing really fundamental about the arrow of time, then: it's all about the existence of a low-entropy state. The arrow of time is really about the existence of a low-entropy state in our very early universe.

    Btw, here's a video of Sean Carroll explaining the arrow of time:
    Last edited by a moderator: Sep 25, 2014
  6. Jan 6, 2014 #5
    A slightly off-topic question:
    Is the cosmological arrow of time a consequence the 2nd law of thermodynamics? I guess what I want to know is if the cosmological and thermodynamic arrows of time are thought to be congruent?
  7. Jan 6, 2014 #6


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    Sort of. It's directly a consequence of a low-entropy boundary condition in our early universe. The second law of thermodynamics describes why this is true.
  8. Jan 14, 2014 #7
    I guess what I'm trying to express is the plausibility of a theory that extends the idea of superposition of a subatomic particle to its relative position, or range, in time. My initial idea led me to consider [itex]_{}P[/itex]tr=[itex]_{}P[/itex]m([itex]1\frac{}{}c[/itex])[itex]\hbar[/itex], where a particle's time range equals its mass times 1 over the speed of light, times planck's constant. In my mind, this could account for such quantum phenomena such as electron orbital jumps, collapsing wave-functions, even superposition itself. I don't think particles transfer very far either direction in time, but the mean could be thought of a the present.
    With respect to entropy in macrotime, I agree with the standard model, except I've often thought that the ordering of information by intelligences might offset the increase of general disorder. And I do understand that the ordering of information is a form of work, which produces heat etc... but I consider this as catch up from either the initial state of the universe or a balancing of a supreme intelligence (blasphemy on these forums, I know). But it's particle time that I'm referring to in my original post.
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