Conservation of matter

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My interest in time travel is mostly curiosity.

However, I've wondered... if the conservation of energy and matter is true, how would that apply to time travel?

If matter is not destroyed then when you time travel to another time, your matter must still exist in your "starting time." Do you now exist in two places? I.e., the typical storyline of a person "disappearing" from one time and appearing in another doesn't make much sense to me.

Additionally, the matter you are made of has always existed. So if you time travel back to 100 years ago, your matter was somewhere. When you "appear" in the other time, where does your physical being come from? Does something in the other time have to disappear to allow you to form? Or has, somehow, new matter appeared in the old time and matter disappaered in the original time? This would seem to be state that the conservation of matter is not true.

If, by appearing in another time, your physical being is created at the expense of whatever your matter was a part of back then (or will be in the future), then it seems to me that this would be detectable by matter disappearing without explanation whenever anything time traveled into our time. This hasn't been detected, has it?

If it hasn't, then it seems to me that either time travel isn't possible or the conservation of matter isn't true.


Craig Steiner
I, personally, do not believe that matter would disappear from one time-line and reappear in another (as seen in the "Back To The Future" movies). Because time is relative to any particular observer, the finite matter which currently exists in the Universe will not increase or decrease but will "appear" to the observer in a different time-line than any other observer. Another way to put this is, "traveling" through time can not be done in the same manner as traveling through space. I believe that time travel would somehow involve shifting relativity. By shifting the time-framed observations of observers, we would cause the observers to shift in time relative to the time traveler. Matter doesn't increase or decrease -- only it's relative relationship to the infinite number of observers in the Universe.

Sound kinda wacky? Got anything better?

Re:Re:Conservation of matter

It seems awfully esoteric to me. Not that I can say it's wrong (who can!)...

In my opinion, time travel can be useful for one of two things: 1) Observing what happened or what will happen. 2) Participating in what happened or what will happen.

Your theory of shifting relative to the observer is ok, but I think that in that case we'd be limited to just #1--just being an observer. We wouldn't really "be there" or be able to participate.

To a certain extent, we can already do that. We look back in time when we look at the stars. If it were possible to send a probe with a super powerful telescope such that, right now, it was 87 light years away, we'd be able to look back at the Atlantic ocean and get REAL footage of the Titanic hitting the iceberg. As an observer, we would have "traveled back in time"--obviously, without actually doing so.

What I think I don't believe (note my uncertainty) is that we can time travel into the future. To get to the future, we'd have to "shift reality" to a reality that will be formed by an infinite number of "decisions" which haven't taken place yet.

The past, in a sense, exists (or existed). It exists as history, as things that have already happened. The infinite number of decisions ocurred to cause what happened to happen. The future, on the other hand, doesn't exist yet. Just as the universe is expanding and we can't go beyond the "edge" of the expanding universe, time is also "expanding" and we can't go beyond the edge of where it has expanded to (the present).

It also seems to me that if we can't go into the future, then we can't actually go into the past. If we could, it would seem logical that we could go back, grab somebody and take them "back to the future" (excuse the pun). To our future. For us, 1999 already exists. For them, it hasn't happened yet and just as we can't go to the future, nor should they be able to go to theirs. But if we're already there, does it make any sense that we could return to where we came from but somebody standing next to us couldn't go with us?

And if we assume that time is a collection of infinite alternate realities, each determined by all the decisions and actions made to get to that point, if we were to time travel into the future, what alternate reality would we arrive in?

Craig Steiner
Re:Re:Re:Conservation of matter

I think your thinking about this is logically sound (Craig): The observer from the future may be able to observe our 'now' but would be unable to participate; whereas travelling to the future is untenable.

Yet, from a purely practical standpoint I think perhaps things have the potential to work better the other way around: The individual traveling through space-time at 90% light-speed returns to an earth that has aged perhaps 150 years, while he himself (we don't have any fems here so I won't worry about being politically correct on the gender thing) has aged only a few months. That person is quite able to participate, whereas it seems quite impossible for our space-time journeyman to go back to his original time.

I don't really care if this is not really "time travel" but only "time dilation", the fact is that, theoretically at least, this works. The relativistic space-time traveller has left one time and arrived in another time -- not that we're not all doing this to a much lesser (un-dilated?) extent every "minute" of our lives.
Radioactive half-lifes at light speed

I agree, that's time dilation. In my opinion it's really only time travel if you leave the time you're in, arrive at another time, and then can come back to where you were. The idea of being 87 light years away and looking back at Earth to see the Titanic crash isn't time travel any more than we are time traveling when we look at the stars.

What you say, traveling at 90% the speed of light, and coming back after 150 earth years having only aged 15 years yourself gets you "to the future." But you haven't really time traveled--you've just done something to effectively extend your life.

Plus it hasn't been determined if, traveling at 90% the speed of light, one could really live longer. Perhaps you can. But perhaps traveling at 90% the speed of light 70 years pass in 7 years. Perhaps you die after what you think is 7 years. Do we really know?

I agree that what you say should happen: The person will feel that 15 years have passed when really 150 years have passed. The question is, will that person still be alive in 10 years? I have a feeling we won't really know until we try.

Here's a related question: What happens if you are traveling at 90% the speed of light and you have some radioactive material with you with a half-life of 100 years. If you travel for 100 earth years, you will feel that only 10 years have passed. How much of the radioactive material you have with you will have decayed? Can radioactive decay be used as a universal measure of time, regardless of the speed at which the radioactive material is traveling?

Craig Steiner
Re:Radioactive half-lifes at light speed

There once lived a girl named Miss Bright,
who could travel faster than light.
She departed one day in a relative way,
and returned on the previous night!

This old limerick states what might happen when we travel at light speeds. In my opinion, I do NOT think this would be the case. As Einstein stated, it's all a matter of relativity. When we speak of "traveling close to the speed of light" -- we must specify, "relative to what?". If we speak of traveling at light speed relative to the earth, then the earth will be traveling at light speed relative to the traveler. I believe that the two will cancel eachother, and therefore will result in no time differece for the traveler or the observer.

Imagine, if you will, a universe that contained only ONE entity... YOU! Now, you decided to buz around this totally empty universe in your warp drive space ship. You say to yourself, "I think I will travel at two times light speed today". Well, the concept of speed could not possibly exist because there is nothing else in your empty universe to relate your speed to! Motion, is only motion when you have some external reference. Now, let's say you have a buddy to share this otherwise empty universe with. He takes off in his warp drive ship at light speed away from you. Now, he can say that he is moving away from you at light speed, or he can say that you are moving away from him at light speed. Either observation would be correct. So, WHO would age, and who would NOT age in this case? Get my point? Because they would move away from eachother at light speed, NEITHER would age any differently relative to eachother. And neither would age any differently relative to any OTHER entities or celestrial bodies in our "normal" universe as we know it.

Enough rambling... Now what do you think about this concept?
Re:Re:Radioactive half-lifes at light speed

What do I think of this concept?

My understanding is that experiments have already been conducted that show time dilation does occur. This time dilation happened at much, much less than the speed of light and the time difference was obviously small. But regardless of the numbers, my understanding is that time dilation has already been proven.

That being case, as logical as what you say sounds, my thought is that something with your concept is wrong. But I'm neither Einstein nor a physicist, so I can't tell you where your logic went astray.

Craig Steiner
Re:Re:Re:Radioactive half-lifes at light speed

You're absolutely correct about the experiments, Craig. I recall reading about an experiment done where a very accurate and precise clock was flown in a rocket (Space Shuttle?) at a very high rate of speed. When the clock was recovered, it was compared with a similar clock that had remained on Earth during the flight. There was a small, but measurable difference between the two (by a few nanoseconds, or a few picoseconds(?)). That experiment was not sufficient evidence to convince me that some sort of time dilation occurred. I believe the difference was more likely caused by something a little more mundane (e.g., vibration from the space craft, high radiation fields in space, accel/decel effects on the clock's electronic components, etc.).

IF time dilation does actually occur due to the relative speeds of moving objects, then there must be an almost infinite number of time dilations taking place all the time in our universe! Think of all the stars, planets, asteroids, etc. that are moving around like molecules in a boiling pot of water. The relative speeds of these bodies must be creating all sorts of time dilations. BUT I believe the net effect is zero! When you perform signal-averageing on "noise", the result you obtain is ZERO! So therefore, because of these canceling effects, time dilation will not, does not, and can not occur. Time dilation is nothing more than a mind game, played by theoretical physicists (and by Hollywood Producers).
Re:Re:Conservation of matter

Wouldnt the second law of thermodynamics mean that no matter can be removed from the Universe?
Re:Re:Conservation of matter

Ever used a word-processing program?
Traveling with the body is like using MOVE, instead of COPY and DELETE.