# ChrisGraley (29.55)

## ChrisGraley's CAPS Blog

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May 17, 2010 – Comments (22)

Just some random thoughts about time and space, but mostly about time.

Those of you not into physics should not read further, but those of you that are might help me with a couple of paradoxes that I've been pondering.

1) If I'm on a ship travelling as close as possible to the speed of light and I fire a gun, even though the bullet that I fire should add it's speed to the ship's speed, physics dictate that the bullet cannot exceed the speed of light and therefore it slows the bullet down in the overall universe. My observation of the bullet on the ship makes the bullet look like it's behaving normally. An outside observer looking at my ship and myself, if they can see me, see both my ship and myself squashed like an accordion. OK, so far, I think everyone that studies Physics agrees, but here come the questions...

a)  If my ship appears compacted from the outside, then the space inside the ship should also appear compacted from the outside. The bullet should appear to have traveled a much shorter distance to the outside observer. In fact, it should look like the bullet just dropped out of the gun like an Elmer Fudd cartoon. Inside the ship, the forces controlling the gun behave as I would expect them to, but outside, the forces seem to change. In the above case, we already know that the speed of my ship is slowing down time, but at least to an outside observer, it would also appear to collapse space and at least observationally alter every other force that we can think of.

Soooo....

Question 1)  The gravity of an object has been known for a long time to distort both space and time. Einstein has made sure to show that the motion of an object distorts time, but as far as I know, no-one has put forth that the motion of an object distorts space. In the above scenario to the outside observer, we distorted space, but I don't notice anything while I'm on the ship, so the known laws of physics appear unbroken to me. Since all science is based on observation, can it be that our observations of every force would change if we had a different mass and were moving at a different speed?

Question 2) If the answer to question 1 is yes, then there has to be an equilibrium. There has to be an average mass and speed for standard observation. Would the cosmological constant come into play here?

Question 3) What are we really doing in science? We are just observing things within the mass of our observation point and the speed of our travel. We do know that at the sub atomic level, we are observing things that are massless and move faster than light. Both of these things may be why we don't have a full grasp at the quantum level.

2) Time travel is possible.

a) If travelling back to the past is at all possible, than given enough time, it would happen. So if it is possible, either humanity ended before we could figure it out, or nobody found any point in history interesting enough to visit to this point, or we visited incognito to avoid altering history. I think that human nature would have made us bold enough to try to alter history, and even if we didn't want to, humans make mistakes. Also, there is the problem of radioactive feedback. If I open a wormhole to the past, it opens to a point in time. As long as that wormhole remains open, everything that enters, travels to that same point in time including all radiation. As long as that wormhole stays open, everything arrives at the same point in time. Imagine just the solar radiation of a wormhole open for a week hitting the same spot in the same split second in time.

b) If travelling to the future was possible, the future would have to exist before you left. Technically, you are just moving faster than observable time, but if you think about it, your movements effect time itself. Even in the void of space, you will displace particles that can alter the future. This would cause fundamental laws of physics to break down before an observer in real time could understand or react. If you actually look at time as a destination, you would have to have a place to go before you could create the wormhole to get there. This creates a few problems. Namely choice and conscious thought. The future can't be linear if you have choices and a brain. The destination to dial in for the wormhole can only take you to one point in time and space and if it took you 10 seconds to get there, a choice made by someone 3 seconds after you left could make it not exist at all and I'm not sure if you would exist at the end of the trip. So if you could travel to the future, all possibilities would have to exist at the same time to make it possible. If all possibilities do exist at the same time, travel to the future is possible, but in order for that to happen, you would need an infinite number of dimensions and string theory would be obliterated

Just some stuff bouncing around in my head. I would appreciate anyone that can provide shade to my blinding stupidity.

Chris,

#1) On May 18, 2010 at 12:00 AM, goalie37 (93.67) wrote:

Nice.  Now to tie it in with what we are about here, if you do travel into the future (and then presumably travel back) please bring back some charts so we can trade it.

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#2) On May 18, 2010 at 12:25 AM, SockMarket (35.64) wrote:

your blogs are always a fun read. a few Q's and possible, but probably wrong, answers from a science novice (feel free not to answer if it gets too long):

1) "even though the bullet that I fire should add it's speed to the ship's speed"

why? for every action there is an equal and opposite reaction. Also if it does normally provide directional momentum wouldn't it depend on what direction you shoot the bullet?

"we already know that the speed of my ship is slowing down time, but at least to an outside observer, it would also appear to collapse space and at least observationally alter every other force that we can think of."

It seems to me that a relativly easy explanation would be that time is simply another dimension--one we can't yet recognize. If that were true the bullet could actually be moving through time... is this true?

also, partly unrelated, is the speed of light the speed of time?

Q1:

"no-one has put forth that the motion of an object distorts space"

I thought spacetime was a distortion of both. Thats what wiki says, do they have it wrong?

2)  "If travelling back to the past is at all possible, than given enough time, it would happen"

:)

"So if it is possible, either humanity ended before we could figure it out, or nobody found any point in history interesting enough to visit to this point, or we visited incognito to avoid altering history. I think that human nature would have made us bold enough to try to alter history, and even if we didn't want to, humans make mistakes."

I would argue that

1) if we ever get intelligent enough to time travel we will probably be reasonable enough to understand the effects of altering history. People would realize that if they do, it is quite likely that they would never be born, so there would be ample reason to both be careful and to not alter it's course

2) mistakes can be corrected, remember, we can go back in time :). If someone makes a mistake (think of the famous butterfly story, the title escapes me now) one can always go back and keep the foot from striking the butterfly.

3) An alternate possibility is that we may finally come to grips with death (personally and as a species) and if that is the case we may have no need to do more than travel back, incognito, and watch. Since it would likely be computer controlled there would be VERY little chance for error.

"As long as that wormhole remains open, everything that enters, travels to that same point in time including all radiation. As long as that wormhole stays open, everything arrives at the same point in time. Imagine just the solar radiation of a wormhole open for a week hitting the same spot in the same split second in time."

If you can manipulate time to this extent, and such strong forces as wormholes, don't you think that we could open and close them simultaneously? I can't think through it all but it is the only thing that makes sense.

2b)

"If travelling to the future was possible, the future would have to exist before you left"

ah, back to my completely unfounded theory that time is just a dimension. Suppose it was, before and after would be like right and left. To someone in 1 dimension going right or left (and forward and back) would seem like magic, kind of like time travel.

If that were the case it would simply be like walking diagonally to a new spot, there would be no before or after to create the problem

"If you actually look at time as a destination, you would have to have a place to go before you could create the wormhole to get there."

But that assumes that you look at time as a linear concept that only moves in 1 direction (at a time, so to speak) and controlls movements within one particular time. I don't know of a good reason why it should, other than that it makes sense to our minds...

My theory is that the reality we preceive only exists in the mind of animals, why? because this is as much of "true" reality as we can preceive and process. So, to really answer quantum physics Q's we must forget the "reality" we know. Kind of a scary thought, but I don't know of another way around it.

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#3) On May 18, 2010 at 12:27 AM, starbucks4ever (99.14) wrote:

"The gravity of an object has been known for a long time to distort both space and time.  Einstein has made sure to show that the motion of an object distorts time, but as far as I know, no-one has put forth that the motion of an object distorts space."

I think you may be confusing Special and General relativity. Time dilation and length contraction are both Special Relativistic effects, and they are due to motion and given by the Lorentz formula. The "distortion" of spacetime due to mass is the basis of General Relativity and it's an entirely different effect that is governed by different equations. As you pointed out yourself, the length of the ship does contract, just as it should in agreement with Special Relativity.

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#4) On May 18, 2010 at 12:58 AM, actuary99 (86.22) wrote:

"1) If I'm on a ship travelling as close as possible to the speed of light and I fire a gun, even though the bullet that I fire should add it's speed to the ship's speed, physics dictate that the bullet cannot exceed the speed of light and therefore it slows the bullet down in the overall universe. "

This is not true.

Traveling "as close as possible to the speed of light" is not possible. For every speed that is less than the speed of light, I can name a speed that is closer than the speed of light.

Second, the bullet does not slow down in the overall universe. The bullet does add its speed to the ship's speed. Relative to you, firing the gun, the bullet travels as fast as it would if you were "stationary" (assuming a vacuum). Even to the observer who is stationary relative to your ship, the bullet's speed exceeds that of the ship, although the observed difference between the velocity of you and the velocity of the bullet is smaller than it is from your frame of reference.

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#5) On May 18, 2010 at 1:14 AM, actuary99 (86.22) wrote:

Einstein's theory, from what I understand, would imply time travel is impossible.

But I would argue time travel is impossible for the same reason Microsoft Excel can't handle circular references. The way people think about traveling backward in time is silly. Everyone seems to assume if you went into the past that you would know what you know in the present. I was born in 1984. If I went back in time to 1986 and know what I know now, I wouldn't be back in 1986, because in 1986, I didn't know what I know now. I'd be in some fake past that was intrinsically different than 1986. So if I stayed in the fake past until the future point where I traveled back into the past, the future (formerly known as the present) would be fake as well, rendering my original trip into the past to be... blah blah infinite loop.

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#6) On May 18, 2010 at 8:07 AM, JakilaTheHun (99.91) wrote:

I'm far, far from an expert on Physics, but my guess is that your hypothetical scenario would be impossible to begin with.  A bullet would not travel very fast in relation to the speed of light.  Therefore, in order to theoretically 'exceed' the speed of light, you would have to already be travelling just a smidge below the speed of light.  However, the properties of the ship, the gun, the bullet, and you would have already changed radically at that point.

A scenario I've often wondered about:

You are traveling on a ship travelling at 3/4 the speed of light.  You are moving directly away from Earth.  However, your ship is part of a reality TV show that is being beamed back to Earth.  How would the people on Earth see you?

I'm assuming it would be in super slow motion, right?  (Since you are travelling away from the Earth at near-light speed, while the transmission would only be able to travel towards Earth at light speed).

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#7) On May 18, 2010 at 8:23 AM, ChrisGraley (29.55) wrote:

daniel, I'll have to wait till after work to reply.

zloj, I think that we agree.

actuary, I think that you misunderstood "as possible" as meaning what Physics would allow and I meant it as meaning what humans could accomplish.

I'm pretty sure that you wouldn't forget what you know in a trip to the past, but here's a paradox for you. If you traveled back in time 10 minutes, then at that point in time there would be 2 of you. If the one that traveled back in time decided to simply wait 10 minutes and the one that was in the past always decided to travel 10 minutes back in time, then you have just created an endless supply of clones. I'm not sure what would happen if you bumped into one of those clones.

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#8) On May 18, 2010 at 8:33 AM, neskolf2 (94.26) wrote:

This is what you do if you bump into clones:

http://www.metacafe.com/watch/986236/the_simpsons_homers_got_a_gun_4_some_clones/

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#9) On May 18, 2010 at 9:38 AM, Seansonfire (34.98) wrote:

"I think that human nature would have made us bold enough to try to alter history"

How would you even know if our current reality or timeline has not been altered by a time traveler that came back, and say drove an asteroid into the earth around the time of the Dinosaurs to allow mammals to become the dominate species of earth.  To assume that we would some how know if a Time Travel has altered our reality is impossible so asking that question is irrelevant.

Q1: can it be that our observations of every force would change if we had a different mass and were moving at a different speed?

Yes.  You have to remember the only true constant in the Universe is the speed of light; everything else bends to allow for the speed of light to stay constant.  Everything.  It turns out that many so called "constants", planks constant etc., actually are not constant, and can change in extreme cases, i.e. at very high speeds or in extreme gravity.

Q2:There has to be an average mass and speed for standard observation. Would the cosmological constant come into play here?

There is an average mass and speed, but determining what that is would be impossible, until you have a "Theory of Everything" connecting Quantum Theory and the Theory of General Relativity.  I believe it has been proven that there is no cosmological constant, as the Universe is always expanding.

Question 3) What are we really doing in science?

I can't say for science as a whole, but I think for Physics they are trying to find the point for which we can say, all of these constants vary because of X by a factor of Y, with an error of Z.  Understanding that would allow you to determine extremes, averages, and ranges for which Physics can be deployed to understand the universe, and also provide insight into phenomena that we don't fully understand (like time travel, black holes, and the expansion/eventual contraction of the universe?).

2) Time travel is possible.

Time Travel is possible, but only going forward not going backward.  This can be done by one of two methods 1) Approaching the Speed of Light for which Time slows down, 2) Being in close proximity to a Super Massive Object, like a black hole, which actually causes time to slow down.  (The earth is actually massive enough to slow down time slightly each day compared to the time in Space around us.  Satellites have to recalibrate their internal clocks for this discrepancy on a regular basis)

b) If travelling to the future was possible, the future would have to exist before you left.

No and Yes. If arriving at the future was possible through time travel then the future would have to exist when you arrived.  If traveling to the future was possible you could do it, and during your trip the Universe could implode and you would never arrive at your future destination. All you are really doing when Time Traveling to the Future is arbitraging the time that you experience with the time that the rest of the universe (namely earth) would experience.  In this case you are slowing down time for you while the rest of the Universe stays on "normal time".

If you are intersted in these type of discussions, I suggest you check out one of the Science forums, where people much smarter than I could probably explain these concepts better. (Sciforum.com)

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#10) On May 18, 2010 at 9:51 AM, USNHR (30.05) wrote:

If you traveled back in time 10 minutes, then at that point in time there would be 2 of you. If the one that traveled back in time decided to simply wait 10 minutes and the one that was in the past always decided to travel 10 minutes back in time, then you have just created an endless supply of clones. I'm not sure what would happen if you bumped into one of those clones.

You are only doubled up for 10 minutes, there is always one going back 10 minutes for your endless supply... however what becomes and endless supply is you living through time... every 10 minutes another you lives through your life. But this isn't happening simultaneously, it is 10 minutes apart.

So the question would be... why doesn't the me sitting in my office chair now, not sit on top of the me, that was here 10 minutes ago sitting in my office chair, or the me that will be here in 10 minutes not sit on me.

Maybe time only exists in the now. So I can't experience the 10 minutes ago/future me.

As for the worm hole, maybe this is why we can't use them. Becuase they can't hold a stationary point in time at one end of the worm hole  (past) and a moving point in time at the other end of the hole (present, now).

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#11) On May 18, 2010 at 9:57 AM, binve (< 20) wrote:

Hey Chris! Sorry I got to this thread late, so most of the observations I would make habe been made by others. But this one

>>Inside the ship, the forces controlling the gun behave as I would expect them to, but outside, the forces seem to change.

might be the problem. I know you are trying to start from a "controlled location" for your thought experiment, but I think this is not a good assumption at relativistic speeds. As since light speed is a theoretical upper limit than means that particles that have mass can only *approach* the speed of light and not ever reach it. This would make the energy requirements to reach light speed expoential / logarithmic. I am saying this to illustrate that forces in the extreme energy density (based on the requirements I just described) of a spacecraft near light speed probably aren't "normal" in any sense of the word.

Not very useful to the conversation, I know, but just a thought :)..

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#12) On May 18, 2010 at 10:41 AM, ChrisGraley (29.55) wrote:

Lot's of good thoughts here.

I can't wait to get home from work to discuss some of these.

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#13) On May 18, 2010 at 2:52 PM, lemoneater (62.62) wrote:

I talked to my favorite science person at lunch. My husband:) He told me that there were many more obstacles to time travel than to flight itself so just because humans have flown, it doesn't necessarily follow that they will be able to travel through time. Before humans flew, we knew flight itself was possible from observing birds and flying bullets, but we do not have any equivalent examples for time travel.

Since I couldn't think of any examples in the natural world of actual time travel, I took a quantum leap and asked what about God? Doesn't he travel through time? His answer was that God transcends time. He is eternal with no beginning or ending. But he enters time when he wishes to interract with humans: Immanuel--God with us.

Well, Chris, I took your question beyond the realm of Science, but somehow it seems appropriate with such a topic as time travel!

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#14) On May 18, 2010 at 3:06 PM, portefeuille (99.10) wrote:

could people here quit writing about physics if I promise to quit writing about "politics"?

russiangambit is of course still allowed to write about physics ...

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#15) On May 18, 2010 at 3:07 PM, portefeuille (99.10) wrote:

(just kidding. go on if you can't help it, hehe ...)

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#16) On May 18, 2010 at 6:21 PM, blesto (30.62) wrote:

"Since all science is based on observation, can it be that our observations of every force would change if we had a different mass and were moving at a different speed?"

Hmmm. No. Everything's relative eh?

For an outside observer to be able to observe, they would need to be at the same speed as you.

When you get an engine that can approach the speed of light we can conduct an experiment.

If reverse time travel were possible, (we're already time traveling foward) then it has already happened and we are now on a different time line. Again.

Again.

I believe you were a seasteader in another time line.

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#17) On May 18, 2010 at 7:23 PM, SolarisKing (< 20) wrote:

#14. heh. I wondered when you would show up.

I think it's hilarious that you didn't bother answering the questions. I think i will join you in your casual observation of the phenomena and also refrain.

Hey fools. A book you might like is 'Dancing Woo Li Masters', and makes reading physics fun.

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#18) On May 18, 2010 at 8:20 PM, ChrisGraley (29.55) wrote:

Oh, now that I have my tinfoil hat on, I've got more!

If a wormhole is essentially a hole in space much like when you put a piece of fabric under a magnifying glass and you see the the space between the threads, and space is a void, then a wormhole is a hole in a void?

If light is composed of massless particles, why is it effected by gravity?

If my ship was a large orb spinning at near the speed of light but not travelling in any direction, would it still slow time? What if I isolated myself so  I wasn't spinning with the rest of the orb?

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#19) On May 18, 2010 at 8:32 PM, blesto (30.62) wrote:

If they ever figure out "Dark Matter", then you should have some good answers to those questions.

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#20) On May 18, 2010 at 10:32 PM, Seansonfire (34.98) wrote:

If a wormhole is essentially a hole in space much like when you put a piece of fabric under a magnifying glass and you see the the space between the threads, and space is a void, then a wormhole is a hole in a void?

I think you need to think about a wormhole as totally flat, it does not take up any space or mass on either side of itself.  The "tunnel" of a wormhole does not actually exist (when you pass through it you actually just move from point A to point B automatically) as if you were stepping through a doorway. Think about it this way, a worm hole is a doorway that has one side in New York City and the other side in Paris, and you can move between the two as easily as you would move through a regular doorway.  The other idea between wormholes that is interesting is that on either side of a wormhole, the time does not have to be the same.  So it could be a doorway from 1982 in New York City to 2001 in Paris.  Although I think the farther apart the time the less stable the wormhole would be, as the only wormholes that currently have been "observed" are on the quantum level and are only a split second apart, and last for less them a millisecond.

If light is composed of massless particles, why is it effected by gravity?

You are correct, Light does not have mass. Gravity actually bends the space-time around it and thus it looks like light is actually bending around massive objects, but it is really just flowing as it would in a vacuum.  Total weird to conceptualize, believe me you need to Google it to understand it.

If my ship was a large orb spinning at near the speed of light but not travelling in any direction, would it still slow time? What if I isolated myself so  I wasn't spinning with the rest of the orb?

No idea on this one, I don't know centrifugal forces that well.  Need a real physicist for that one.

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#21) On May 23, 2010 at 10:53 AM, Teacherman1 (< 20) wrote:

I think you got it right Lemoneater. There is only one who has stepped out of Etermnity and into Time and He didn't write a book about it. At least not a book on Physics. But like you probably do, I think that one day we will have all the answers to the questions Chris has put forth, when we too step out of time and into eternity.

Time is a human concept and exists only in our limited perception. From the viewpoint of God, there is no time. There is no beginning and no end, only eternity, which has always been and will always be.

Have a nice Sunday everyone. Mental exercises are good and can produce some useful results, as long as you realize that your ultimate understanding will always be limited.

It's also good for the Spirit as well as the Soul.

JMO, but in this case, worth much more than I am charging for it.

In keeping with the basic purpose of this Community:

Buy banks, or don't, based on your own understanding of Time and what will happen in it. :)

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#22) On May 24, 2010 at 10:41 PM, l3jardin (< 20) wrote:

Not a pro in General Rel or Wormholes, but I am at least a real live physicist, and I did used to teach Special Rel.  So:  I'm impressed that you realized that the apparent forces would be different!  Don't know if I'm answering your question here, but just in case you didn't know, mass also changes relativistically, inversely to length (i.e., as gamma); so if a bullet were traveling 87% of c (root-3 over 2 the speed of light), it would appear twice as massive to a stationary observer.

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