Geeky Science Question

[crackerkorean]

Ok I was thinking about this for a bit and wanted a reasonable rebuttal and/or answer.

WARNING: Some brain injury can occur if you think too hard.

Is time travel possible? My problem with the whole idea is the law of the conservation of mass. Basically stating that you cannot remove matter from a system (in this case right now in this universe).

I have one good response that requires me to read a bit but just figured that i would get your thoughts.

[Urizen]

Until man can travel past the speed of light, we are stuck where we are.:smoke:

[Sandy G]

Well, funny you should bring this up-there's an article about it in the Coast-To-Coast website. Apparently, even the great physicist Stephen Hawking cannot find anything in the laws of physics preventing it. However, it just may not be practical. I don't think we will have to worry about it in our lifetimes.

[dread31]

I kinda doubt it. And I have a suspicion that moving faster than light will just make it difficult to see, but no time travel will take place. You'll just get from point A to point B a whole lot faster.

But, what do I know, I'm just a mechanic.

Dave

[Sir.Byrd]

The grandfather paradox disproves time travel IMO
http://en.wikipedia.org/wiki/Grandfather_Paradox

[onepixel]

IF we could travel through a warp in space-time by creating a wormhole we could travel to the future but not the past.

But if travel to the past was possible there would have to be alternate realities or histories. Otherwise the paradox thing would drive you nuts.

:)

[Sir.Byrd]

I think we all shouldn't think about it cause we'll be dead by the time we could even remotely do this.

[outshined]

Currently, the science of time travel is limited to travelling into the future, which has been proved in lab experiments (in super-conducting colliders)

The catch is, one must travel at near light speed. Travelling at light speed is strictly forbidden by the laws of physics. If, say just for arguments sake, you were in a car doing light speed, and you turned on the headlights, the light would move away from you at, that's right, the speed of light!

Travelling at close to light speed is for all intents and purposes, at this time, unachievable, if ever.

One of the best books on the subject, and my personal favorite, is "Time Machines Time Travel in Physics, Metaphysics, and Science Fiction" by Paul J. Nahin.

There are some mind blowing paradoxes connected with time travel, and this book will, er, blow your mind!

[MRX37]

I believe in an infinite number of paralell universes, so perhaps the past still exists in some form.

I think a new paralell universe is created everytime an event happens... which would means billions of new universes every second... Each universe may differ in only slight ways... perhaps there is a universe in which I never posted this, but nothing else is different.

In the universe where I never posted this, no one would read this post, and the topic would probably go off in a different direction. Perhaps someone else would post something similar. Perhaps someone would flame this topic... If paralell universes exist, anything could happen in them.

[MRX37]

Another thing I would like to add:

I anticipate someone saying something like: "Well if theres paralell universes, where ANYTHING can happen, why hasnt someone contacted us from a parallel universe?"

Maybe someday they will. Maybe they never will... If anything can happen, it stands to reason that anything can just as well NOT happen.

Perhaps it has happened, but it happened to another universe almost indistinguishable from ours...

[outshined]

I believe in an infinite number of paralell universes, so perhaps the past still exists in some form.

I think a new paralell universe is created everytime an event happens... which would means billions of new universes every second... Each universe may differ in only slight ways... perhaps there is a universe in which I never posted this, but nothing else is different.

In the universe where I never posted this, no one would read this post, and the topic would probably go off in a different direction. Perhaps someone else would post something similar. Perhaps someone would flame this topic... If paralell universes exist, anything could happen in them.

This is the "Many Worlds Paradox"

Many scientists believe this is like trillions of alternative Universes, as you described so well, as tiny bubbles all stuck together in a vast conglomerate.

We cannot see them. But, perhaps, we may visit one through a worm hole.

[outshined]

Another thing I would like to add:

I anticipate someone saying something like: "Well if theres paralell universes, where ANYTHING can happen, why hasnt someone contacted us from a parallel universe?"

Maybe someday they will. Maybe they never will... If anything can happen, it stands to reason that anything can just as well NOT happen.

Perhaps it has happened, but it happened to another universe almost indistinguishable from ours...

This topic has been a fascinating one for me since I was a kid.

There is, to address your post, nothing in physics to prevent anything from happening.

A glass that has fallen from a table and shattered can, according to the laws of physics, jump right back on the table and reconstruct itself. Yes!

The reason we don't see this happen is that, while it can happen, it would take so long to occur (trillions upon trillions of years the size of the universe) that renders it a moot point.

[hypertone]

I've given this considerable thought in my younger days, and the only I answer I have for you is - drugs are bad, mmmkay.

[onepixel]

...I thought I said all that.

:)

Stephen Hawking's A Brief History in Time and The Universe in a Nutshell are excellent reads. Not only is the guy brilliant but he has a wonderful sense of humor.

[Sir.Byrd]

You guys are crazy.

[vinyldavid]

This is the "Many Worlds Paradox"

Many scientists believe this is like trillions of alternative Universes, as you described so well, as tiny bubbles all stuck together in a vast conglomerate.

We cannot see them. But, perhaps, we may visit one through a worm hole.

If you want to know more, read Michio Kaku's Parallel Worlds. Took me a couple of tries to understand it all, but HIGHLY recommended reading. :yes: :thmbsp:

[stratmel]

It would be cool to travel back in time - take some cash to snag all the McIntosh and Dahlquist you coveted then...

[E2theNth]

Prepay a storage space for 20 years and you'd be sittin pretty.

The Grandfather Paradox is an interesting concept; I definitely think timelines are fixed to a certain degree. This isn't to say everything is all fate and you have no choice in the matter; instead I think milestones are fixed, but are different for everyone and more developmental than physical. The whole parallel time thing is too tricky because I'd hate for there to some kind of alternate me on some other plane of reality.

God forbid he listens to his 128bit mp3 rips from his Ipod on 80's gear!

[Sandy G]

I'd like to back to 1954 in some close-paralell reality & buy up a bunch of CT-100s..Maybe in THAT reality, the CRTs wouldn't go south, either...

[Darkspeed]

If you take mass out of the equation using a gyro effect, I think we will surpass lightspeed......perhaps not in our lifetime......but I think it is possible. There was a show on Coast to Coast one time some years ago, in which a guy was talking about achieving some mass-cancelling effects with gyros in a sort of flying vehicle.

ps I bet John Hutchison could figure some way to send you somewhere into time.......possibly killing you but.........lol

Always a great debate though!!!!

[cityflux]

"Time is the greatest juggler, humans are the greatest dupes" - From 'The Book Of Mirdad'. If you ever get the chance, read it!

All is one, one is all. Time can be overcome but not in the physical realm; time is a creation of the mind and an illusion. When time can be stilled in your own heart, all will be revealed.

Easier said than done :nono:

[crackerkorean]

My problem with the whole thing is how do you get around the conservation of matter and energy.
http://www.cartage.org.lb/en/themes/Sciences/Chemistry/Generalchemistry/Energy/LawofConservation/LawofConservation.htm

These are fundamentals in physics and I am curious as how these people explain getting around this. Since there is a finite amount of energy in this universe how can we remove something or person from this universe and and put it in anohter one?

Even on that same note time, at this moment that you read this "word" to the moment in you read this "word", energy is the same reguardless. So how could one remove energy/matter from right now and move it to then?

When then happens there is extra energy which cannot be done.

Time is not an illusion, time is a measurement of moments that humans created to track moments in an organized fashion. Like miles/kilometers are measurements of distance.

[outshined]

My problem with the whole thing is how do you get around the conservation of matter and energy.
http://www.cartage.org.lb/en/themes/Sciences/Chemistry/Generalchemistry/Energy/LawofConservation/LawofConservation.htm

These are fundamentals in physics and I am curious as how these people explain getting around this. Since there is a finite amount of energy in this universe how can we remove something or person from this universe and and put it in anohter one?

Even on that same note time, at this moment that you read this "word" to the moment in you read this "word", energy is the same reguardless. So how could one remove energy/matter from right now and move it to then?

When then happens there is extra energy which cannot be done.

Time is not an illusion, time is a measurement of moments that humans created to track moments in an organized fashion. Like miles/kilometers are measurements of distance.

It's called the "Conservation of Energy" and was developed by Newton and expanded by Einstein.

Just as time and space are inextricably intertwined, so is matter and energy.

There is no "extra" energy. No free lunch.

[crackerkorean]

It's called the "Conservation of Energy" and was developed by Newton and expanded by Einstein.

Just as time and space are inextricably intertwined, so is matter and energy.

There is no "extra" energy. No free lunch.

There is conservation of mass and conservation of energy, didnt mean conservation of "mass and energy"

What I am saying is that thats the problem with time travel there is no extra energy. Its finite. So when something time travels to some time else it breaks this finite rule.

Hope this makes more sense as to what my problem is what time travel.

[similost]

I remember reading somewhere that NASA had changed time in an experiment. They put a clock on a spaceship, (can't remember which flight it was, and can't find an article on it) and another on the ground and synced them. After the ship got back, they found the time on the ship was just a couple seconds or half seconds or similar off. They said it was because of the speed of the ship was much greater than the other clock was moving.. so speed does allow time travel, maybe not enough at the time being, for a human to make much notice of it, but by hurling through space at great speeds, a select few have traveled into time, albeit a minuscule distance

[outshined]

I remember reading somewhere that NASA had changed time in an experiment. They put a clock on a spaceship, (can't remember which flight it was, and can't find an article on it) and another on the ground and synced them. After the ship got back, they found the time on the ship was just a couple seconds or half seconds or similar off. They said it was because of the speed of the ship was much greater than the other clock was moving.. so speed does allow time travel, maybe not enough at the time being, for a human to make much notice of it, but by hurling through space at great speeds, a select few have traveled into time, albeit a minuscule distance

Not so much speed as gravity.

Clocks move faster, say, in the Shuttle because there is less gravitational force in space than on the Earth. The difference is, as you rightly point out, very small. Astronauts will gain about about 2-3 seconds of time when they return.

So, they are "younger" than when they left!

[outshined]

There is conservation of mass and conservation of energy, didnt mean conservation of "mass and energy"

What I am saying is that thats the problem with time travel there is no extra energy. Its finite. So when something time travels to some time else it breaks this finite rule.

Hope this makes more sense as to what my problem is what time travel.

I think that, all else being equal, and even in the realm of time travel, the conservation rule should still apply.

It applies here and everywhere in the Universe. Even black holes have been shown, by Hawking, to release energy as well as devouring it.

[Scuzzer]

What I am saying is that thats the problem with time travel there is no extra energy. Its finite. So when something time travels to some time else it breaks this finite rule.


Finite does not mean fixed. I don't believe anyone's come up with a theory that says our universe has to have X amount of energy. Besides, some of the greatest minds in physics haven't come up with a reason why time travel is impossible, just that it's highly improbable.

[outshined]

Finite does not mean fixed. I don't believe anyone's come up with a theory that says our universe has to have X amount of energy. Besides, some of the greatest minds in physics haven't come up with a reason why time travel is impossible, just that it's highly improbable.

Time travel into the future is indeed very problematic, but not impossible.

It has been proven in particle accelerators. Particles that should last only billionths of a second will last much, much longer when accelerated to 99% of the speed of light.

This would be the same for humans travelling at that same speed, with reference to the Earth or other starting point.

Time for them would progress normally, but to us, their clocks would appear to be standing still. We would watch this for years and years, with only a few hours of time seen passing for them.

They would return to find that we are long dead and gone, while they are only a few years even a couple of decades older.

[Scuzzer]

This would be the same for humans travelling at that same speed, with reference to the Earth or other starting point.

Time for them would progress normally, but to us, their clocks would appear to be standing still. We would watch this for years and years, with only a few hours of time seen passing for them.



Agreed, but that's where the highly improbable comes from. Since mass increases the faster you go it takes so much energy to accelerate a spaceship to any significant fraction of the speed of light that it might as well be impossible. You'd also need twice as much energy because it would take the same amount to slow down as to accelerate.

I think the more interesting question is: Can we transmit information to the future and could they then transmit back to us? Perhaps we could devise a way (micro wormhole?) to transmit and receive information outside of space-time. It might be difficult though because once you turned on the receiver everyone from the future would be broadcasting to you at the same time! Perhaps we'd need the FCC to stipulate bandwidth allocations before the thing was even built.

[jimfet]

Can ya'll get me a bag of that stuff?

[crackerkorean]

Can ya'll get me a bag of that stuff?

Scary thing is there is no bag involved.....for me anyway. I cannot speak for anybody else.

[dread31]

Not so much speed as gravity.

Clocks move faster, say, in the Shuttle because there is less gravitational force in space than on the Earth. The difference is, as you rightly point out, very small. Astronauts will gain about about 2-3 seconds of time when they return.

So, they are "younger" than when they left!


If the clocks move faster due to lower gravitational force, then couldn't it be said that this is due to a mechanical function, and not to an actual warpage in time itself? The parts of the the clock (Even if they are atomic particles.) being able to move somewhat more freely in a low, or no gravity situation?

I would think the perception of time, from the vantage point of the astronauts themselves, gauged against the succession of events in their environment, would remain constant. In other words, they would age the same, whether in space, or on earth. It would merely be the accuracy of the instrument that has skewed.:scratch2:

Dave

[outshined]

Agreed, but that's where the highly improbable comes from. Since mass increases the faster you go it takes so much energy to accelerate a spaceship to any significant fraction of the speed of light that it might as well be impossible. You'd also need twice as much energy because it would take the same amount to slow down as to accelerate.

I think the more interesting question is: Can we transmit information to the future and could they then transmit back to us? Perhaps we could devise a way (micro wormhole?) to transmit and receive information outside of space-time. It might be difficult though because once you turned on the receiver everyone from the future would be broadcasting to you at the same time! Perhaps we'd need the FCC to stipulate bandwidth allocations before the thing was even built.

Transmitting info into the future was addressed by Rosen and Einstein, in the "ERP" or, Einstein-Rosen Paradox. It was an attempt to show how two particles, leaving at the source at the same time at light speed, could "know" what the other particle was doing.

This was to refute Niels Bohr's assertion that there is no correlation. Einstein called it "spooky action at a distance" Bohr won the argument.

But, you are correct about the fact that it takes, if travelling at light speed, an infinite amount of energy. Also, the ship, as it were, would take on an infinite amount of mass. This alone proves that time travel, or interstellar travel, with the technology of conventional propulsion will never come into play.

Transmitting into the future seems like a viable way to "get there" But, normal microwave, radiowave and other forms of radiation capable of data retention will disperse after only about 50 light years into space. Beings on other planets will not be watching re-runs of I Love Lucy... Even light itself loses mass and energy after a long period, although one can argue that the light coming from a Quasar 12 billion light years away still has energy because we can detect it.

Also, what about people living in the future? If backwards time travel were possible, then where are they? If the future holds the key to travelling back in time, at some point a visitor would have travelled back to tell us. But, therein lies another paradox! Not to mention no one would believe such a person, unless he can prove what he says by demonstrating the super advanced technology.

This is a fun subject, but also a serious one. If we can travel into the future, just as a thought experiment for now, at least, we would be able to bring back cures for disease, social and self sustaining, peaceful ways of governing, etc, because more than likely, these things would exist through wisdom and the belief that it is better to be a peaceful civilization.

I believe that through Quantum Mechanics, we will one day be able to transmit, instantaneously, data to the future, where it may be picked up by a superior race of beings. They would undoubtably be so much more technologically advanced than ourselves, that the info we send may just prove to be a passing curiosity to them, and we will not receive a reply.

[outshined]

If the clocks move faster due to lower gravitational force, then couldn't it be said that this is due to a mechanical function, and not to an actual warpage in time itself? The parts of the the clock (Even if they are atomic particles.) being able to move somewhat more freely in a low, or no gravity situation?

I would think the perception of time, from the vantage point of the astronauts themselves, gauged against the succession of events in their environment, would remain constant. In other words, they would age the same, whether in space, or on earth. It would merely be the accuracy of the instrument that has scewed.:scratch2:

Dave

No... Clocks, move slower on the ground level of the Empire State Building than on the observation deck. The time effect is real.

This is a function of spacetime and gravity, and is incorporated into our biological clocks as well.

Particles (atoms, electrons, and sub atomic particles all follow this natural course of nature, without regard to whether or not it's "right")

These are the frames of reference that are part of Einsteins Special Theory of Relativity. My frame of reference is right for me, but not for you, at close to light speed. I might see something in your future, even though the event happens only once, but, they are valid in our perspective frames of reference.

[similost]

No... Clocks, move slower on the ground level of the Empire State Building than on the observation deck.

This is a function of spacetime and gravity, and is incorporated into our biological clocks as well.

Particles (atoms, electrons, and sub atomic particles all follow this natural course of nature, without regard to whether or not it's "right")

These are the frames of reference that are part of Einsteins Special Theory of Relativity. My frame of reference is right for me, but not for you, at close to light speed. I might see something in your future, even though the event happens only once, but, they are valid in our perspective frames of reference.

I think we are only talking mechanical clocks here being hampered by gravity. I can't see how a digital all electronic clock could be effected by gravity. Seems gravity wouldn't have enough effects on electrons to effect the pace of time being kept.

I'd also like to see something that backs up the fact of time of two clocks seperated by 1200 feet or so would be effected by gravity that much.. we would be talking such a small difference in gauss, it would almost not be measurable..

[pahtcenter77]

Go back in time?

Possibly re-live an in-excess-of-twenty-five-year marriage?

Uh...............??????

[outshined]

I think we are only talking mechanical clocks here being hampered by gravity. I can't see how a digital all electronic clock could be effected by gravity. Seems gravity wouldn't have enough effects on electrons to effect the pace of time being kept.

It is definitely a little crazy sounding, but, it is true.

Any device is made of particles at the sub atomic level, and if you had a clock, such as an atomic clock, then it would seem to make more sense.

All matter is subject to this seemingly impossible way that matter behaves in varying degrees of gravitational fields, but, does indeed, behave accordingly.

And, yes, the effect is very subtle at this level, but has been measured and verified.

[outshined]

Go back in time?

Possibly re-live an in-excess-of-twenty-five-year marriage?

Uh...............??????

It is still not known whether backwards time travel is possible. Some physicists have worked out the math, and the general theory is that if we can go faster than light, then we can travel back in time.

The problem is, we cannot go faster than light by "conventional" means. And the paradoxes are insurmountable, as far as we can tell, unless the "Many Worlds" theory is correct.

If I could go back, with the knowledge I have now, I would return as almost super human, and with around $1 billion trillion bucks. (And that would be chump change. lol)

[Arkay]

Time travel is actually very easy, once you know how. I've done it! :yes: It is true that it only works towards the future, not the past, so don't worry about the grandfather paradox and all that stuff.

Actually, I've been doing it constantly (AFAIK) for almost fifty years already, traveling right through time, always towards the future... it's quite a ride, although not always quite what one's imagination could wish for.

:D

[Scuzzer]

This was to refute Niels Bohr's assertion that there is no correlation. Einstein called it "spooky action at a distance" Bohr won the argument.


The "spooky action at a distance" thing still throws me for a loop. Allow two particles to entangle, move them a large distance apart and they still act like they're connected even though information would have to move faster than light to make it happen.

Weirdness like that is not only theorized but proven, leaving me to believe that we've barely scratched the surface when it comes to quantum events.

As to your point about where are all the "future" people. I'd guess that you'd need to build a portal on this end for time travel to work and until one is built you won't have any "future vacationers" visiting us. On the other hand it would be like my receiver comment above. If you built a successful time travel port you'd know it as soon as you switched it on because a few million(?) people would come pouring out.

[outshined]

The "spooky action at a distance" thing still throws me for a loop. Allow two particles to entangle, move them a large distance apart and they still act like they're connected even though information would have to move faster than light to make it happen.

Weirdness like that is not only theorized but proven, leaving me to believe that we've barely scratched the surface when it comes to quantum events.

As to your point about where are all the "future" people. I'd guess that you'd need to build a portal on this end for time travel to work and until one is built you won't have any "future vacationers" visiting us. On the other hand it would be like my receiver comment above. If you built a successful time travel port you'd know it as soon as you switched it on because a few million(?) people would come pouring out.

It bothers me, too, that although the ERP seems to work out beautifully, and was a stroke of, dare I say "genius" on Einsteins part, it violates Einsteins own law that says nothing can travel faster than light! Yet, it seems to be true... We're obviously missing something, and the culprit is QM at its' very heart.

About the time portal; I can see your point. But, what if an intrepid astronaut made a round trip journey at 99% light speed to Alpha Centauri, turned around, re-accelerated and came back to Earth. He would certainly be in our future, although there wasn't a time portal built here before he left.

Could he not just return the same way he left? I don't know the answer, but it's a thought. Then again, there may be people from the future here right now, whos' mission it is to record the history of this period. They would then go "back" to the future and report their findings.

If they are here, and causality really does play a role in backwards time travel, meaning that future events could and would be changed, then it makes sense that our friends from the future cannot interact with us in any way.

[sleddogman]

As has been noted, one has to keep in mind that as one approaches the speed of light, time (as we know it) slows down. The difference noted between the two clocks mentioned (ground and space shuttle) has nothing to do with gravity, but rather the speed at which both clocks are/have traveled -- relative to each other. Gravity is only a factor if the clocks are mechanical. If they're digital, then it's a moot point. However small the difference, the faster you go relative to a stationary object that you're comparing it to, the slower time becomes.

So, a clock in orbit whizzing around at thousands of miles an hour faster than the clock on the ground will experience a minute time shift because it's traveling faster than the clock on the ground (i.e., a bit closer to the speed of light.) Do you fly a lot in jet airplanes at 400-500 mph? Every time you do you've added minute factions of seconds to your lifespan based on the duration of the time spent in the cabin compared to if you had just been standing on the ground.

Riddle me this, Batman: If a clock on Earth is moving at 25,000 mph (the rotational speed of the planet) compounded by the Earth's rotational speed around the Sun and a clock is placed far enough out in space so that it's merely another object traveling at the basic speed of the revolving Milky Way galaxy, would the clock on Earth run faster than the clock out in suspended space? :scratch2:

[onepixel]

So what happens when you bend and slow down the speed of light? With enough bends to a specific endpoint, a direct line would beat it there.

:D

[outshined]

Time travel is actually very easy, once you know how. I've done it! :yes: It is true that it only works towards the future, not the past, so don't worry about the grandfather paradox and all that stuff.

Actually, I've been doing it constantly (AFAIK) for almost fifty years already, traveling right through time, always towards the future... it's quite a ride, although not always quite what one's imagination could wish for.

:D

Well, I can't argue with you too much!

We tend to think of time and space as seperate things... But, they are not. We also tend to think of time as a linear, unstopable consequence of existance, much to my dissatisfaction, if you ask me.

But the means to flit through spacetime is, I believe, quite possible. Now, here's where I meant that I'm dissatisfied with the consequence of linear time: There's apparently nothing we can do to change it. At least not yet. And when and if we do, I won't be around to see it realized.

Pity...

[outshined]

So what happens when you bend and slow down the speed of light? With enough bends to a specific endpoint, a direct line would beat it there.

:D

Good try:thmbsp: If you take the straight line approach, its' light will still be the same speed, though not quite as fast as light in zero gravity. They arrive at the same time.

But, again, the laws that govern speed, light and gravity all follow the rules, no matter how we try to bend them. :no:

[outshined]

As has been noted, one has to keep in mind that as one approaches the speed of light, time (as we know it) slows down. The difference noted between the two clocks mentioned (ground and space shuttle) has nothing to do with gravity, but rather the speed at which both clocks are/have traveled -- relative to each other. Gravity is only a factor if the clocks are mechanical. If they're digital, then it's a moot point. However small the difference, the faster you go relative to a stationary object that you're comparing it to, the slower time becomes.

So, a clock in orbit whizzing around at thousands of miles an hour faster than the clock on the ground will experience a minute time shift because it's traveling faster than the clock on the ground (i.e., a bit closer to the speed of light.) Do you fly a lot in jet airplanes at 400-500 mph? Every time you do you've added minute factions of seconds to your lifespan based on the duration of the time spent in the cabin compared to if you had just been standing on the ground.

Riddle me this, Batman: If a clock on Earth is moving at 25,000 mph (the rotational speed of the planet) compounded by the Earth's rotational speed around the Sun and a clock is placed far enough out in space so that it's merely another object traveling at the basic speed of the revolving Milky Way galaxy, would the clock on Earth run faster than the clock out in suspended space? :scratch2:

It takes 250M years for the Galaxy to rotate once. We've been around 20 times.

The clock out in space, away from any influence of gravity, and is stationary will always run faster, relative (reference frame) to the terrestrial clock.

As I've said, clocks, no matter how they keep time, will always be under the influence of their gravitational field.

Two clocks in a zero gravity situation can only be judged by one frame of reference to each other, even though they are "supposed" to be keeping exact time with respect to one another. The reason they don't, and it's true in the real sense, is the different frame of reference.

At close to light speed, each frame of reference is true for each observer.

[onepixel]

Good try:thmbsp: If you take the straight line approach, its' light will still be the same speed, though not quite as fast as light in zero gravity. They arrive at the same time.

But, again, the laws that govern speed, light and gravity all follow the rules, no matter how we try to bend them. :no:

Are you saying light that is bent and travels farther will arrive at the same time as a direct line?

Any implications on Harvard physicist Lene Hau's expirement of slowing down the speed of light to 38 mph. On a good day I could beat that on my bike.

Ain't science cool?

:D

[outshined]

Are you saying light that is bent and travels farther will arrive at the same time as a direct line?

Any implications on Harvard physicist Lene Hau's expirement of slowing down the speed of light to 38 mph. On a good day I could beat that on my bike.

Ain't science cool?

:D

Science is cool!

You must remember, refractive bending of light slows down the speed of light. But, if we are to measure with accuracy, then we cannot change the rules.

In every day life, a straight line is always the shortest distance. Or, is it?

Experiments done on curved objects prove otherwise. I must admit, I'm not too familiar with this assertion. A parallel can be seen with refracted light.

Now, how does the Prof. slow down light to 38 mph?!

[onepixel]

I'm not talking about bending light through refraction, but bending it with a black hole. Where space/time is warped through massive gravitational forces.

DIY... how to slow down time.
http://www.hno.harvard.edu/gazette/1999/02.18/light.html

Seems Prof. Hau went as far as to stopping light.
http://www.physics.wsu.edu/Announcements/Upcoming/Hau.html

[outshined]

I'm not talking about bending light through refraction, but bending it with a black hole. Where space/time is warped through massive gravitational forces.

DIY... how to slow down time.
http://www.hno.harvard.edu/gazette/1999/02.18/light.html

Seems Prof. Hau went as far as to stopping light.
http://www.physics.wsu.edu/Announcements/Upcoming/Hau.html

This is fascinating stuff. Like a laser, but many, many times more coherent. Although the hardware used is pretty exotic, I hope this application will find its' way to the practical applications mentioned.

One use that wasn't mentioned, but might be possible, is to use this slowed light in a scanning-tunneling electron microscope. The greatly reduced energy could be used to observe particles (atoms, mostly) without knocking them around.

To get really crazy... Might it be possible to one day get around the Heisenberg Principle, where one can measure both the position and the momentum of an atom?:scratch2:

That would be tremendous. And then, theoretically anyway, we can predict the entire future of the Universe if this were known.

Whoa.

[Sandy G]

Another thing about going the speed of light, or presumably faster: Basically, it can't be done. I remember from when I WASN'T napping in a hiskule physics class that the closer you approach the speed of light, the more INFINITELY heavier you become, & you decrease infinitely in length as well. Supposedly, to go the speed of light in say a Saturn-5 rocket would require more energy than has ever existed on earth, & as you approached the speed of light, yr spaceship would get shorter & shorter... This is all part of the screwy world of quantum mechanics & physics, where Schrodlinger's Cat can be dead & alive at the same time, & other nonsensical, but apparently true, impossibilities.

[outshined]

"...This is all part of the screwy world of quantum mechanics & physics, where Schrodlinger's Cat can be dead & alive at the same time, & other nonsensical, but apparently true, impossibilities.[/QUOTE]

Quantum Mechanics can be totally mind blowing.
I've tried to explain, the best I could, anyway, the paradox of Schrodingers Cat and its' implications, but I don't think anyone believed it's true.

One other reality of QM is the tenet that nothing (in the sub atomic world) is real. Much like Schrodingers Cat, you have to look at it, and, in the process, become intertwined with the experiment, thereby becoming part of the particle, so to speak.

But, one can't say a particle is real, or even exists, without first looking at it or "collapsing the wave function" Same as looking in the box with the cat in it to see whether she's dead or alive.

I find this all very good stuff. But, I don't think it'll get legs here, unless other, interested parties want to chime in.

Most, but not all, of QM's tenets have been shown to be true in lab tests.

[sleddogman]

Science is cool!

In every day life, a straight line is always the shortest distance. Or, is it?

Experiments done on curved objects prove otherwise. I must admit, I'm not too familiar with this assertion. A parallel can be seen with refracted light.

Don Herbert, aka Mr. Wizard (rest his soul), explained way back in my grade school days that the shortest distance between two points on a sphere, like the Earth, is known as The Great Arc, which equates to the diameter of the sphere. Therefore, the shortest distance will always be where the sphere's diameter passes through both points.

Airlines always try to fly the shortest distance using The Great Arc, especially over long distances. For example, Chicago to Tokyo takes the plane up through Minnesota, into Canada, across the Aleutian islands of Alaska and then down along the Russian Kamchatka peninsula towards Japan. When this flight path is drawn on a flat map, the result is a curve that represents the diameter (or equator) of the Earth passing through both cities.

[dread31]

So, if time travel is only possible (Supposedly.) into the future, then once in the future, you could not return, right? Say we find a way to time travel, ummm---tomorrow morning. Hypotheyically. A dude steps into the machine and, (pffft), disappears. How do we know it was a success? He can't come back and report, now can he? And if, (Again, hypothetically.), he went, oh, a hundred years ahead. Wouldn't the people he encounters already be accustomed to time travel? So, he zaps into the future, only to find out that nobody gives a s**t. ("Yeah, so what?"). Kind of sad if you think about it.

I say that unless we can acheive two way time travel that there is no point in bothering. Go ahead in time to tell folks something they already know?

I dunno, I guess it would be cool to be the time traveler. See how certain things turn out.

Dave

[outshined]

Don Herbert, aka Mr. Wizard (rest his soul), explained way back in my grade school days that the shortest distance between two points on a sphere, like the Earth, is known as The Great Arc, which equates to the diameter of the sphere. Therefore, the shortest distance will always be where the sphere's diameter passes through both points.

Airlines always try to fly the shortest distance using The Great Arc, especially over long distances. For example, Chicago to Tokyo takes the plane up through Minnesota, into Canada, across the Aleutian islands of Alaska and then down along the Russian Kamchatka peninsula towards Japan. When this flight path is drawn on a flat map, the result is a curve that represents the diameter (or equator) of the Earth passing through both cities.

Thanks for clarifying.

[outshined]

So, if time travel is only possible (Supposedly.) into the future, then once in the future, you could not return, right? Say we find a way to time travel, ummm---tomorrow morning. Hypotheyically. A dude steps into the machine and, (pffft), disappears. How do we know it was a success? He can't come back and report, now can he? And if, (Again, hypothetically.), he went, oh, a hundred years ahead. Wouldn't the people he encounters already be accustomed to time travel? So, he zaps into the future, only to find out that nobody gives a s**t. ("Yeah, so what?"). Kind of sad if you think about it.

I say that unless we can acheive two way time travel that there is no point in bothering. Go ahead in time to tell folks something they already know?

I dunno, I guess it would be cool to be the time traveler. See how certain things turn out.

Dave

Dave, You're thinking in terms of absolute space and time. To travel into the future, a "machine" will not work. If there were such a machine, and you hit the forward lever (as in "The Time Machine" with Rod Taylor) you would instantaneously be destroyed into atoms.

One can travel into the future. This is a fact, limited only by present technology. I'm sure that plans would be laid down explaining what is taking place, who is going, and when they will return. They would be waiting for him to return.

But, I do see a paradox that you allude to. Namely, the time traveller goes 100 years into the future, and returns. But, in that 100 that has passed (Earth time) we have invented time travel. BUT, how does the technology exist in the first place in order to send the traveller into the future? We must have had to come up with it somehow. Maybe the traveller invented it himself.

So, the original traveller goes into the future, where time travel is commonplace. But, again, if it's invented in the future, how did he get there?

This same paradox will always exist, no matter when forward time travel is realized.

The only way out of the paradox will be for the traveller, who discovers that he is in the history books as being the first time traveller! How do the future inhabitants of Earth know this? Well, after the traveller arrives into the future, he stays.

Since this has already happened in the future, the people are well aware of the traveller and might be waiting for him to appear.

Dave, here's another little tid bit: You can travel (yes, you) into, say, next Monday. OK. You then return to the present, and time travel to the Sunday right before the Monday you originally went to. If you wait at the same exact spot you were on Monday, you will see yourself appear on Monday!

Tomorrow I will post a mind blowing paradox of time travel, which would have grave, though unforseen consequences. Stay tuned!

[outshined]

Don Herbert, aka Mr. Wizard (rest his soul), explained way back in my grade school days that the shortest distance between two points on a sphere, like the Earth, is known as The Great Arc, which equates to the diameter of the sphere. Therefore, the shortest distance will always be where the sphere's diameter passes through both points.

Airlines always try to fly the shortest distance using The Great Arc, especially over long distances. For example, Chicago to Tokyo takes the plane up through Minnesota, into Canada, across the Aleutian islands of Alaska and then down along the Russian Kamchatka peninsula towards Japan. When this flight path is drawn on a flat map, the result is a curve that represents the diameter (or equator) of the Earth passing through both cities.

Yes, indeedy! Thanks for this very good analogy, it's what I was alluding to.

[outshined]

"...This is all part of the screwy world of quantum mechanics & physics, where Schrodlinger's Cat can be dead & alive at the same time, & other nonsensical, but apparently true, impossibilities.

Niels Bohr once said "If it sounds crazy, then it won't do, because it's not crazy enough"

[onepixel]

So, if time travel is only possible (Supposedly.) into the future, then once in the future, you could not return, right?


You can return. You could time travel to a "point", 1000 years into the future. But return a second after you left. From that reference point you would have not traveled back in time.

:)

[outshined]

I'd like to add one more thing... Purely a thought experiment.
Suppose time travel becomes a reality, and we are free to travel into the future at will.

Well, how far can we go? One hundred years? A million? If we can always travel farther and farther into the future, then why not go all the way 'till the end of the Universe? (Our Universe, that is)

There should be no reason why we couldn't. But, this implies that the future is there, in real terms. So? Well, then the entire history of the Universe has already taken place, and we are simply watching it unfold as it happens.

This takes away any need for a god or supreme being. There is no free will. I'm typing this because it was destined to be. I cannot take it back. It was not my choice... Some will say it was my choice, because I had to think about doing it, go to my puter, log on to AK, and start typing away.

I say that, since it has happened, it was destiny, not free will.

Gonna be a lonely place in a Universe with nothing but burnt out stars and a few helium atoms here and there. The hydrogen is long gone...

[outshined]

British philosopher Jonathan Harrison posed the following astonishing situation. (1979)

A young lady, one Jocasta Jones, one day finds an ancient deep freezer containing the solidly frozen young man. She thaws him out and discovers his name is Dum and that he possesses a book that describes how to make both a deep freezer and a time machine.
They marry. Soon they have a baby boy and name him Dee. Years later, after reading his fathers book, Dee makes a time machine. Dee and Dum, taking the book with them, get into the machine, and begin a trip into the past. Running out of food during the lengthy journey Dee kills his father and eats him.
Arriving in the past, Dee destroys the time machine, builds a deep freezer (using the book), gets into it and... wakes up to find a young lady, one Jocasta Jones, has thawed him out.
When asked his name, he replies Dum, shows Jocasta his book, they marry, and...

Did Jocasta commit a logically possible crime? This issue is but one of an ocean of puzzles found in this story! Jocastas crime, of course, is that she has seemingly (if unwittingly) commited incest; readers who remember their Greek mythology, and the story of Oedipus and who his mother/wife was, will now see why Harrison named his heroine as he did.
But, what of Dees crime? He has, after all, eaten his father. But, perhaps it isn't a crime after all, because Dee and Dum are one in the same, and is it a crime to eat yourself? One response to this story is that it is so extravagant in its' implications, that it will be regarde by many as a dubious assumption on which it rests, namely, the possibility of time travel.

A more thoughtful response, which also makes the interesting observation that not only has Jocasta committed incest, but has done so with a single act of intercouse. The events in a causal loop do not happen endlessly, but rather only once, and Jocasta thaws Dum (Dee) out just once, marries him just once, and the two consummate their marriage only once.

Ordinarily we think it takes two sexual acts to commit incest, with the first resulting in the birth of a child, and the second being union with the child, but this is not so in a causal loop. Time travel IS an odd business.

Another rebuke to the story makes the telling point that irrespective of physics, the story is biologically flawed, and fatally so. As it goes, "Dee is the son of Dum and Jocasta. So Dee obtained half his genes from Dum and half from Jocasta. But Dum is diachronically identical with Dee, and is therefore genotypically identical with him (i.e. himself) That is, Dee is BOTH Genotypically IDENTICAL with and DISTINCT with Dum, which is absurd.

But Harrison dismisses this a "mere law of nature, not of logic"
Can one person be two people? In time travel, it just might be so.

[sleddogman]

I'm thinking of reinstating my previous signature line in honor of this thread... :D



http://i85.photobucket.com/albums/k55/sleddogman/Ad.jpg

[outshined]

I'm thinking of reinstating my previous signature line in honor of this thread... :D



http://i85.photobucket.com/albums/k55/sleddogman/Ad.jpg

this link isn't working, at least not for me... Funny, it's not in your post but when I try to quote it, it appears. But, still doesnt work. :scratch2:

[sleddogman]

this link isn't working, at least not for me... Funny, it's not in your post but when I try to quote it, it appears. But, still doesnt work. :scratch2:
Might be because it's in my Photobucket account. Here it is as an attachment in case you wanted it.

[Kyle85318531]

Man, for some reason, I find the subject of time travel really depressing..

That sig is awesome though, nonetheless. :D

Ky

[Sandy G]

I did some time-traveling about 10,15 years ago. Can't tell you how I did it, that's still classified, and, erm, the statute of limitations may not have run out. I CAN tell you I went to Alton, Illinois, in 1958. Big deal. They kept playing that Art & Dotty Todd song "Chanson D'Amour"-"Rat-ta-dat-da-da..." over & over. I was glad to get back.

[outshined]

Might be because it's in my Photobucket account. Here it is as an attachment in case you wanted it.

Where did you find this ad?! It's unreal, and tailor made for this thread.
Now I'm super curious what it was all about. Something nefarious, if you ask me.

[outshined]

[QUOTE=Kyle85318531;1774260]Man, for some reason, I find the subject of time travel really depressing..

Why depressing?

I'm just curious about it. I wouldn't mind going back in time. See dinos, ancient Rome, try and shake Einsteins hand (and tell him I'm from the future LOL) etc.

It would be a verrrry profitable venture as well, wouldn't you say? :banana:

[chillwolf]

I have time traveled during some of my out of body experiences! So it is possible, but not in the physical plane. :sigh: