Monday, August 13, 2012

Time Is But a Measure of Change


I saw another episode of the thought provoking TV-series Through the Wormhole, and here I go again: this time about time. I doubt that it exists as an entity of its own. It's just a convention we choose in order to note and measure change. That's all there is: change.

I find it amusing that Einstein, who revolutionized time by making it relative, only implies it in his famous formula E=mc^2. Energy is timeless, so is mass, but c, which stands for the speed of light, needs time to have a quantity. It travels this distance in that time.

What really happens is that the light changes location, being constantly on the move. It was there, now it's here. And it went this way. That's just as true for any object in the universe. Planets move, galaxies move, continuously. Time is a way of describing change, but it isn't the change. The movement is. Time is a tool by which the observer can measure the change.

Light is again odd in this perspective, since time ceases to exist at its speed. If you could travel at the speed of light, time would stretch out infinitely. You would remain in the instant forever. That makes it impossible for you to at all perceive that you exist. So, light has no subjective existence. It only exists to us observers, traveling at a lesser speed.

So, with Einstein's formula as well as with other methods, we measure time by an entity that is timeless by nature.

Anyway, Einstein was far from the first to realize the relativity of time. That's how we all experience it. Sometimes it's slow, sometimes fast, and sometimes we forget about it completely, as if it ceased to exist for a while. The Wormhole episode mentioned how time goes faster the older we get, even presenting a formula for it. Alas, I know that.

What we relate to, and the whole universe with us, is change. If nothing changed, it would be like no time. Existence would be completely immeasurable. In all practicality, it would not exist.

The complexity of the universe as we experience it allows for countless changes. Every situation is in some way unique, separable from every other event. The sun rises and sets, day after day, but the view is never identical.

We live in a cosmos where its parts interact in patterns so complicated that no pattern is repeated. It's caused by what's called entropy, but I prefer the word disorder. Cracks in the uniformity increase. That causes change, which gives us the ability to perceive time passing.

Choosing time as a measure of change, we jump to conclusions about the universe. Because time consists of a past and a future, we search for a beginning and an end. Change in itself makes no such demand. We also expect some kind of continuity and consistency – again, that's nothing change in itself postulates.

Everything changes. Time, too. Maybe there could suddenly be a change of change, so that it stopped. If so, there would be no way of observing it.

The idea of change being a core ingredient in the world is well-established in ancient Eastern thought. It's even the title of one of the oldest Chinese books, I Ching, The Book of Change, traditionally used for divination. If you want to understand what might happen, you must start by accepting that everything changes, whether you like it or not. Be consoled by the fact that if there were no change, we wouldn't be.

Time is a line from the past to the future, but we really have no other experience of it than the moving point on the line that is the present. At any given moment, we are in the present, with both the past and the future elsewhere. That's how we experience it. Time is not a boat ride, but a stream passing us as we stand firmly in the middle of ourselves.

I look in the mirror and can compute, although with some difficulty, that I've grown older. Well, my face has. But me, I'm the same. It doesn't happen to what's really me, whatever that is. Time is no illusion, but it's not an adequate description of what we go through in our lives. It's just one way of looking at it.

12 comments:

  1. If you travel at the speed of light,
    time would stretch out infinitely for an outside spectator,
    not for the person traveling at the speed of light.

    Time is a line from the past to the future.

    Yes, but what if time has two or more dimensions?
    Then thoses virtual particles popping in and out of existence
    would not seem so strange?

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    1. What would be the time experience of somebody traveling at the speed of light?

      In a multidimensional universe, surely time can have a couple of them. That would mean the possibility of shortcuts and traveling just about anywhere in time.

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    2. Time slows down when you approach the speed of light.
      This is because atomic particles don't decay as quickly near the speed of light.

      But to reach the actual speed of light that requires an infinite amount of energy.
      Alcubierre drive might solve the problem,
      but for that to work we need negative energy, whatever that is?


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    3. Of course, according to present physics we can't travel at the speed of light. It wouldn't be a pretty sight if we tried.

      But how about light - does it age at all? If not, it reamins in an eternal present.

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    4. A photon is massless, this is why it can travel at lightspeed.
      So the question is can something without mass age?

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    5. My impression is that light is massless because the law of relativity demands it of something with that speed. But it has mass in the sense that it's affected by gravity. I might misunderstand.

      Anyway, the question is if something without mass can change. If it can, this might be possible to describe as ageing. If it can't, then it can't age either.

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    6. I found the formula for time in relation to velocity, on the NASA website:

      "The standard equation for 'time dilation' is that the time passing on Earth will equal the time on the object * 1/sqrt(1-((v*v)/(c*c))), where v is the velocity of the object and c is the speed of light. At v=c this goes to infinity, or in other words, time would stop for an object moving at the speed of light. This is not a problem because objects can't go at the speed of light -- it would take an infinite amount of energy (and their mass would also become infinite).
      Dr. Eric Christian"

      So it seems that to photons it's an eternal now.
      Also, isn't the formula surprisingly simple and elegant?

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    Replies
    1. The existence of an arrow of time does not rule out a flow of time.
      Logically, however, if time did flow, it need not be in the direction indicated by the arrow.
      Time could flow from future to past, and an observer would then
      see events "going backwards" relative to our own experience of the world.

      Or in Einsteins own words:

      "The distinction between past, present, and the future is
      only a stubbornly persistent illusion."

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    2. Maybe time is flowing backwards in our universe. How would we notice it?

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    3. I guess we would not notice it, because we
      have nothing to compare with?

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    4. That's my guess, too. Time going this way or that makes no difference for those enclosed by it.

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