If we ever do get time travel, I want to make a game show out of it.
Like, have all the contestants sign papers saying we can't be held responsible for injuries or death, and give them something to do in the past. Like, "Escape Hirsohima before the bomb drops," or "Find a way off the Titanic." It'd be fun and educational.
I just wanted to comment on time travel being possible, but not before the first time machine was built. A lot of people are disagreeing with this, but it actually does work in some conceptions of time travel.
Basically, it's the wormhole theory of time travel. You create a wormhole, one end on Earth, the other being carried by a ship going near the speed of light. When the ship stops, it's one hundred years in the future, but the wormhole it's carrying still leads to Earth from where it left. All of a sudden you have a time machine that allows you to travel from when it was built to one hundred years in the future.
Of course, this theory requires wormholes to exist, and to be somehow transportable by human methods, and any number of complications. And it could very well still be completely impossible. However, it does posit a system where the time traveller cannot go further back than the creation of the time machine, for a logical reason.
Basically what I'm saying is that while time travel may very well be impossible, a lot of the common logical objections against it may be irrelevent since the "can't go back past the creation of the time machine" idea is at least theoretically plausible.
I just wanted to comment on time travel being possible, but not before the first time machine was built. A lot of people are disagreeing with this, but it actually does work in some conceptions of time travel.
I just wanted to comment on time travel being possible, but not before the first time machine was built. A lot of people are disagreeing with this, but it actually does work in some conceptions of time travel.
TIME DOES NOT WORK THAT WAY.
Neither does physics, or science in general.
Um, actually, it does. There is nothing in our modern understanding of physics which would preclude us from logically creating a wormhole, taking one end and zooming around the galaxy really fast, and then returning. When you returned the other end of the wormhole would still be in the past, at the point in time at which you left it.
The problems with us ever realizing this goal are manifold, but they're ones of practicality. We would need an insane, insane, insane amount of energy to open and sustain a wormhole, and we would need it in a form hitherto undiscovered. The equations say that it IS theoretically possible, however.
I just wanted to comment on time travel being possible, but not before the first time machine was built. A lot of people are disagreeing with this, but it actually does work in some conceptions of time travel.
TIME DOES NOT WORK THAT WAY.
Neither does physics, or science in general.
Okay.
I'm mainly running on what I've read about Kip Thorne's stuff on the subject here, but I'm not going to pretend I have enough grouding in it to argue the point properly. Still, do you mind commenting on what exactly about it doesn't work?
I just wanted to comment on time travel being possible, but not before the first time machine was built. A lot of people are disagreeing with this, but it actually does work in some conceptions of time travel.
TIME DOES NOT WORK THAT WAY.
Neither does physics, or science in general.
Okay.
I'm mainly running on what I've read about Kip Thorne's stuff on the subject here, but I'm not going to pretend I have enough grouding in it to argue the point properly. Still, do you mind commenting on what exactly about it doesn't work?
Because if Time Travel were physically possible, and it isn't, it would be possible whenever conditions were similar to it being possible, not just because it's discovered. That's an arbitrary boundary. If it were possible, and it isn't, then what if some race on the other side of the galaxy had already discovered it? It would be possible here. It would also be possible if no other race had discovered it.
Fencingsax on
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OtakuD00DCan I hit the exploding rocks?San DiegoRegistered Userregular
You might as well say "you can only time travel back as far as the point where everyone believes time travel is real."
So in other words, the Technocracy preventing time travel from existing by making sure nobody believes it exists!
Time travel is a silly sci-fi idea. Now, universal constructors? That's what'll make humanity immortal.
SPIRIT NUKE! SPIRIT NUKE!
Seriously though. Maybe there's no time travelers because people in the future fucking know better than to mess with the past and risk screwing EVERYTHING up?
The problems with us ever realizing this goal are manifold, but they're ones of practicality. We would need an insane, insane, insane amount of energy to open and sustain a wormhole, and we would need it in a form hitherto undiscovered. The equations say that it IS theoretically possible, however.
SAYS THE MAN WHOSE AVATAR IS TIMECUBE WEARING A SANTA HAT
Mr_Rose83 Blue Ridge Protects the HolyRegistered Userregular
edited December 2006
True, the idea that time travel is impossible before it is discovered is stupid. What is true however, is that no time-travel device can be configured to send an object to a point before the device was built.
Thus, we have no (human) time travellers popping up around here because no-one has built a time travel device yet (around here at any rate)...
This does not however preclude the possibility of time travel being developed by someone else at some point, someone who might not have any interest in Earth's history because they have never heard of us.
I feel like you guys have taken no physics courses, only sci-fi lit courses.
Seriously, even the guy linked in the OP with a Ph.D in Physics is completely nuts.
He thinks channeling light through a medium is equivalent to lowering c itself. It doesn't fucking work that way.
I was like "okay, he's just one of those fringe theory people" until I got to that part. He absolutely should not have a Ph.D in Physics if he thinks that.
I feel like you guys have taken no physics courses, only sci-fi lit courses.
Seriously, even the guy linked in the OP with a Ph.D in Physics is completely nuts.
He thinks channeling light through a medium is equivalent to lowering c itself. It doesn't fucking work that way.
I was like "okay, he's just one of those fringe theory people" until I got to that part. He absolutely should not have a Ph.D in Physics if he thinks that.
The more I read the more I realize that they'll give just about anyone a Ph.D just to get rid of them.
I feel like you guys have taken no physics courses, only sci-fi lit courses.
Seriously, even the guy linked in the OP with a Ph.D in Physics is completely nuts.
He thinks channeling light through a medium is equivalent to lowering c itself. It doesn't fucking work that way.
I was like "okay, he's just one of those fringe theory people" until I got to that part. He absolutely should not have a Ph.D in Physics if he thinks that.
Well, it depends what the research he did towards a PhD was on. Having a PhD doesn't suddenly turn you into an all-knowing master on whatever subject it was on.
Coldred on
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Mr_Rose83 Blue Ridge Protects the HolyRegistered Userregular
edited December 2006
Also, it's not like PhD is the highest rank you can get in the sciences.
On the other hand, would someone like to explain why channelling light through a medium wouldn't slow it down? Or did someone actually try to change a universal constant?
I feel like you guys have taken no physics courses, only sci-fi lit courses.
Seriously, even the guy linked in the OP with a Ph.D in Physics is completely nuts.
He thinks channeling light through a medium is equivalent to lowering c itself. It doesn't fucking work that way.
I was like "okay, he's just one of those fringe theory people" until I got to that part. He absolutely should not have a Ph.D in Physics if he thinks that.
I was in no way condoning the idiocy of the OP's links.
I was explaining the views of many modern physicists.
There is nothing that theoretically prevents the construction of a time "machine" in the form of a wormhole. There are many reasons why we won't be able to build one, but there's nothing that theoretically prevents it.
Also, it's not like PhD is the highest rank you can get in the sciences.
On the other hand, would someone like to explain why channelling light through a medium wouldn't slow it down? Or did someone actually try to change a universal constant?
Yeah, the idea is that light slows down in a medium, but c stays the same.
And c of course is usually called "the speed of light" but what it really is is "the speed of light in a vacuum" and of course it also controls all kinds of other things like like the propagation of forces and whatnot, which unlike photons I'm pretty sure don't change speed in a medium.
Also, it's not like PhD is the highest rank you can get in the sciences.
On the other hand, would someone like to explain why channelling light through a medium wouldn't slow it down? Or did someone actually try to change a universal constant?
Yeah, the idea is that light slows down in a medium, but c stays the same.
And c of course is usually called "the speed of light" but what it really is is "the speed of light in a vacuum" and of course it also controls all kinds of other things like like the propagation of forces and whatnot, which unlike photons I'm pretty sure don't change speed in a medium.
Wait, now I'm confused. What do you mean exactly by propagation of forces?
Don't photons mediate the electromagnetic force?
I've actually never heard about this specifically, so maybe that means something other than what I thought it means. I am on uncertain ground.
Also, it's not like PhD is the highest rank you can get in the sciences.
On the other hand, would someone like to explain why channelling light through a medium wouldn't slow it down? Or did someone actually try to change a universal constant?
Yeah, the idea is that light slows down in a medium, but c stays the same.
And c of course is usually called "the speed of light" but what it really is is "the speed of light in a vacuum" and of course it also controls all kinds of other things like like the propagation of forces and whatnot, which unlike photons I'm pretty sure don't change speed in a medium.
Wait, now I'm confused. What do you mean exactly by propagation of forces?
Don't photons mediate the electromagnetic force?
I've actually never heard about this specifically, so maybe that means something other than what I thought it means. I am on uncertain ground.
I think, although I'm not entirely certain (although I should know this), that refractive index is a macroscopic quantity whereas when you talk about propagation of forces you're talking at a quantum level.
Edit: And of course phase velocity vs. group velocity stuff
You might as well say "you can only time travel back as far as the point where everyone believes time travel is real."
So in other words, the Technocracy preventing time travel from existing by making sure nobody believes it exists!
I think the point is that you need a receiving technogadget unit this end.
You know... the same way you couldn't hear radio signals by inventing and building one radio. You needed at least two.
The second you build the sending unit, you've built the receiving unit.
This actually has to do with the definition of time too. Whether the past is the past and has happened, the present is the present and is currently happening, and the future is the future and has not yet happened, or if the past, present, and future are all currently happening at the same time, and we're only viewing the part we exist in. If the former is true, time travel isn't possible. If the latter is true, as soon as you build the device in the present, the future has the device too, and it can be used instantly, to even travel into the further past and deliver another unit.
Isn't there a theory that says something about divergent universes? Something along the lines of; we exist in an universe that does not yet have time travel, because when one went back, he created a split.
I.E. Bob goes back in time to 1990, two universes are split, one in which he made it back, and everyone learns about time travel, and one (which we currently exist in) where he failed to make it back, or landed in a vacuum and died without a trace.
Time travel is impossible because time is a delusion, one of the main building blocks of the mental construct that is the human ego. Even on the more mundane level of time and logic, lets say you did manage to travel somewhere back or forward in time - it still wouldn't be any other time besides "right now". There is nothing other than the eternal present.
Time travel is impossible because time is a delusion, one of the main building blocks of the mental construct that is the human ego. Even on the more mundane level of time and logic, lets say you did manage to travel somewhere back or forward in time - it still wouldn't be any other time besides "right now". There is nothing other than eternal present.
Time travel is impossible because time is a delusion, one of the main building blocks of the mental construct that is the human ego. Even on the more mundane level of time and logic, lets say you did manage to travel somewhere back or forward in time - it still wouldn't be any other time besides "right now". There is nothing other than eternal present.
I don't think my, or anyone else's here for that matter, knowledge on the subject is as good as that of the Ph.D. dude.
While having a Ph.D. doesn't necessarily make him an all-knowing expert, it makes him a much more knowing expert than any of us, and he no doubt has heard the sorts of criticisms and opposition we are voicing here a billion times.
What I do know is to never call a scientist nuts. Remember the whole Galileo thing? "omg he thinks the world revolves around the sun lol"
This whole discussion reminds me of what Shinto said a while ago, about a bunch of non-experts arguing about expert subjects and that being a good definition of these forums. Not that that's a bad thing.
In any case, the person who manages to accomplish time travel, or anything groundbreaking for that matter, will be viewed with contempt and mild amusement until the very moment he accomplishes it.
Also, it's not like PhD is the highest rank you can get in the sciences.
On the other hand, would someone like to explain why channelling light through a medium wouldn't slow it down? Or did someone actually try to change a universal constant?
Yeah, the idea is that light slows down in a medium, but c stays the same.
And c of course is usually called "the speed of light" but what it really is is "the speed of light in a vacuum" and of course it also controls all kinds of other things like like the propagation of forces and whatnot, which unlike photons I'm pretty sure don't change speed in a medium.
Wait, now I'm confused. What do you mean exactly by propagation of forces?
Don't photons mediate the electromagnetic force?
I've actually never heard about this specifically, so maybe that means something other than what I thought it means. I am on uncertain ground.
Er, well I was mostly thinking of whatever mediates the strong and weak nuclear force. And the graviton. Assuming it exists. All those move at c, right? And I doubt they slow down in a medium. Especially not the nuclear forces, I'd imagine, since they're smaller than any possible medium
Also, it's not like PhD is the highest rank you can get in the sciences.
On the other hand, would someone like to explain why channelling light through a medium wouldn't slow it down? Or did someone actually try to change a universal constant?
Yeah, the idea is that light slows down in a medium, but c stays the same.
And c of course is usually called "the speed of light" but what it really is is "the speed of light in a vacuum" and of course it also controls all kinds of other things like like the propagation of forces and whatnot, which unlike photons I'm pretty sure don't change speed in a medium.
Wait, now I'm confused. What do you mean exactly by propagation of forces?
Don't photons mediate the electromagnetic force?
I've actually never heard about this specifically, so maybe that means something other than what I thought it means. I am on uncertain ground.
Er, well I was mostly thinking of whatever mediates the strong and weak nuclear force. And the graviton. Assuming it exists. All those move at c, right? And I doubt they slow down in a medium. Especially not the nuclear forces, I'd imagine, since they're smaller than any possible medium
I might just be confused.
W and Z bosons (weak carriers) and gluons (strong carrier) normally cannot travel freely, and W and Z bosons have mass, so cannot travel at c. In fact the mass of the W and Z bosons are what limit the weak forces range, whereas the massless nature of the photon gives the electromagnetic force an infinite range.
Also, it's not like PhD is the highest rank you can get in the sciences.
On the other hand, would someone like to explain why channelling light through a medium wouldn't slow it down? Or did someone actually try to change a universal constant?
Yeah, the idea is that light slows down in a medium, but c stays the same.
And c of course is usually called "the speed of light" but what it really is is "the speed of light in a vacuum" and of course it also controls all kinds of other things like like the propagation of forces and whatnot, which unlike photons I'm pretty sure don't change speed in a medium.
Wait, now I'm confused. What do you mean exactly by propagation of forces?
Don't photons mediate the electromagnetic force?
I've actually never heard about this specifically, so maybe that means something other than what I thought it means. I am on uncertain ground.
Er, well I was mostly thinking of whatever mediates the strong and weak nuclear force. And the graviton. Assuming it exists. All those move at c, right? And I doubt they slow down in a medium. Especially not the nuclear forces, I'd imagine, since they're smaller than any possible medium
I might just be confused.
W and Z bosons (weak carriers) and gluons (strong carrier) normally cannot travel freely, and W and Z bosons have mass, so cannot travel at c. In fact the mass of the W and Z bosons are what limit the weak forces range, whereas the massless nature of the photon gives the electromagnetic force an infinite range.
Correct, and gravitational propagation has been observed to have a speed at least very similar to c.
True, the idea that time travel is impossible before it is discovered is stupid. What is true however, is that no time-travel device can be configured to send an object to a point before the device was built.
This is the correct answer, although bear in mind it only holds true for one specific type of time travel idea and that's the one the guy with the circling light beams is working on.
Time travel as achieved by wormholes etc. doesn't necessarily have this pre-requisite since you can create the wormhole in the future in such a way that it loops into the past. However on further analysis of techniques like this, it does seem to indicate some sort of chronological protection at work in the universe, in that a lot of them seem conceptually possible but then you get down and simulate the fine detail they collapse just before coming together - i.e. the universe may be suitable for life specifically because you can't do time travel in it, or something similar.
Ugh, the sidebar on that article is a bad start to the whole thing. A photon is a spin-1 particle so the fact that electrons and positrons have spin-1/2 is perfectly consistent. (Sorry you'll have to read the article to see that.)
Edit: The rest of his stuff might be fine, but talking about how you're fighting the established science community and then making a fundamental error like that, well, it's pretty dumb.
Also, it's not like PhD is the highest rank you can get in the sciences.
On the other hand, would someone like to explain why channelling light through a medium wouldn't slow it down? Or did someone actually try to change a universal constant?
Yeah, the idea is that light slows down in a medium, but c stays the same.
And c of course is usually called "the speed of light" but what it really is is "the speed of light in a vacuum" and of course it also controls all kinds of other things like like the propagation of forces and whatnot, which unlike photons I'm pretty sure don't change speed in a medium.
Wait, now I'm confused. What do you mean exactly by propagation of forces?
Don't photons mediate the electromagnetic force?
I've actually never heard about this specifically, so maybe that means something other than what I thought it means. I am on uncertain ground.
Er, well I was mostly thinking of whatever mediates the strong and weak nuclear force. And the graviton. Assuming it exists. All those move at c, right? And I doubt they slow down in a medium. Especially not the nuclear forces, I'd imagine, since they're smaller than any possible medium
I might just be confused.
W and Z bosons (weak carriers) and gluons (strong carrier) normally cannot travel freely, and W and Z bosons have mass, so cannot travel at c. In fact the mass of the W and Z bosons are what limit the weak forces range, whereas the massless nature of the photon gives the electromagnetic force an infinite range.
Ugh, the sidebar on that article is a bad start to the whole thing. A photon is a spin-1 particle so the fact that electrons and positrons have spin-1/2 is perfectly consistent. (Sorry you'll have to read the article to see that.)
I feel like you guys have taken no physics courses, only sci-fi lit courses.
Seriously, even the guy linked in the OP with a Ph.D in Physics is completely nuts.
He thinks channeling light through a medium is equivalent to lowering c itself. It doesn't fucking work that way.
It kind of does, actually. I mean, Snell's Law is a byproduct of light being actually different speeds within different media, and if you manage to get a particle faster than the localized speed of light, you get Cherenkov radiation, which is weird shit.
I've never had anyone actually explain why light slows down in media, but there's more to it than you might think.
I feel like you guys have taken no physics courses, only sci-fi lit courses.
Seriously, even the guy linked in the OP with a Ph.D in Physics is completely nuts.
He thinks channeling light through a medium is equivalent to lowering c itself. It doesn't fucking work that way.
It kind of does, actually. I mean, Snell's Law is a byproduct of light being actually different speeds within different media, and if you manage to get a particle faster than the localized speed of light, you get Cherenkov radiation, which is weird shit.
I've never had anyone actually explain why light slows down in media, but there's more to it than you might think.
Ugh, the sidebar on that article is a bad start to the whole thing. A photon is a spin-1 particle so the fact that electrons and positrons have spin-1/2 is perfectly consistent. (Sorry you'll have to read the article to see that.)
Edit: The rest of his stuff might be fine, but talking about how you're fighting the established science community and then making a fundamental error like that, well, it's pretty dumb.
I also seriously doubt that the professor threatened him for asking a question. It screams made up.
Dramatization:
"We don't talk about that," the professor said coldly, narrowing his eyes on me. "And you," he emphasized the word, thrusting a pudgy finger at me, "won't either." He collected himself and put his hand palm-down on the table. "That is, not if you want to pass this course."
Afterwards, I overheard him in the teacher's lounge. "I doubt we'll have any more problems with Mr. Hoston," he cackled loudly and very sinisterly. His remark was met with much hooting from the entire gathered scientific establishment. "No, I solved that problem. Inform the Overlord!"
Realizing their plot, it dawned on me that I could not sit idly by and allow the conspiracy to continue. I must major in French literature and write about physics on the Internet.
I feel like you guys have taken no physics courses, only sci-fi lit courses.
Seriously, even the guy linked in the OP with a Ph.D in Physics is completely nuts.
He thinks channeling light through a medium is equivalent to lowering c itself. It doesn't fucking work that way.
It kind of does, actually. I mean, Snell's Law is a byproduct of light being actually different speeds within different media, and if you manage to get a particle faster than the localized speed of light, you get Cherenkov radiation, which is weird shit.
I've never had anyone actually explain why light slows down in media, but there's more to it than you might think.
But c never changes. It's the speed of light in a vacuum.
As I understand it - granted, I only learned about this one is a very introductory physics course, so it may not be entirely true, or even inherently flawed, like a lot of what I learned in that class - the reason light slows down in a medium is because the photons are absorbed by particles - say, an electron - and then spit back out a bit later as the particle returns to a lower energy state.
I mean, unless we're talking about gravity, a media doesn't really distort the world around it to make light go slower. Media are still mostly empty space (how would you define a medium?). So, if that class was correct, the individual free photons are still always traveling at c, but the net speed of the light is reduced because the photons are being constantly stopped by the particles of the medium.
Ugh, the sidebar on that article is a bad start to the whole thing. A photon is a spin-1 particle so the fact that electrons and positrons have spin-1/2 is perfectly consistent. (Sorry you'll have to read the article to see that.)
Edit: The rest of his stuff might be fine, but talking about how you're fighting the established science community and then making a fundamental error like that, well, it's pretty dumb.
I also seriously doubt that the professor threatened him for asking a question. It screams made up.
Dramatization:
"We don't talk about that," the professor said coldly, narrowing his eyes on me. "And you," he emphasized the word, thrusting a pudgy finger at me, "won't either." He collected himself and put his hand palm-down on the table. "That is, not if you want to pass this course."
Afterwards, I overheard him in the teacher's lounge. "I doubt we'll have any more problems with Mr. Hoston," he cackled loudly and very sinisterly. His remark was met with much hooting from the entire gathered scientific establishment. "No, I solved that problem. Inform the Overlord!"
Realizing their plot, it dawned on me that I could not sit idly by and allow the conspiracy to continue. I must major in French literature and write about physics on the Internet.
I'm not buying it.
Hahahaha! I've heard this story, sold to me on the Steorn forums as someone's own. Of course I knew it was bullshit then (just about everyone there seems to feel slighted by science in some way and what's to stick it to 'dem physicists) but it's now even more hilarious that the whole thing was ripped from somewhere else.
Ugh, the sidebar on that article is a bad start to the whole thing. A photon is a spin-1 particle so the fact that electrons and positrons have spin-1/2 is perfectly consistent. (Sorry you'll have to read the article to see that.)
Edit: The rest of his stuff might be fine, but talking about how you're fighting the established science community and then making a fundamental error like that, well, it's pretty dumb.
I also seriously doubt that the professor threatened him for asking a question. It screams made up.
Dramatization:
"We don't talk about that," the professor said coldly, narrowing his eyes on me. "And you," he emphasized the word, thrusting a pudgy finger at me, "won't either." He collected himself and put his hand palm-down on the table. "That is, not if you want to pass this course."
Afterwards, I overheard him in the teacher's lounge. "I doubt we'll have any more problems with Mr. Hoston," he cackled loudly and very sinisterly. His remark was met with much hooting from the entire gathered scientific establishment. "No, I solved that problem. Inform the Overlord!"
Realizing their plot, it dawned on me that I could not sit idly by and allow the conspiracy to continue. I must major in French literature and write about physics on the Internet.
I'm not buying it.
Hahahaha! I've heard this story, sold to me on the Steorn forums as someone's own. Of course I knew it was bullshit then (just about everyone there seems to feel slighted by science in some way and what's to stick it to 'dem physicists) but it's now even more hilarious that the whole thing was ripped from somewhere else.
Wait, what? I just wrote that.
I seriously doubt a professor would act that way, is all.
As I understand it - granted, I only learned about this one is a very introductory physics course, so it may not be entirely true, or even inherently flawed, like a lot of what I learned in that class - the reason light slows down in a medium is because the photons are absorbed by particles - say, an electron - and then spit back out a bit later as the particle returns to a lower energy state.
I don't think this is entirely correct. I mean, it is one process, but I'm pretty sure it's not a process specifically related to Snell's law since there's a lot of research focussed on slowing down light which seems to be very much about slowing down the same beam of light. And they can do some impressive stuff - get it down to only a few meters per seconds which is an enormous reduction.
I would *guess* that the Snell's law process would be related to the interaction of the electromagnetic field of a light beam with the stationary fields of the material it's passing through, because you're right, matter is mostly empty space under one assumption, but that space is actually most definitely quite full of electric and magnetic fields from atoms.
Posts
Like, have all the contestants sign papers saying we can't be held responsible for injuries or death, and give them something to do in the past. Like, "Escape Hirsohima before the bomb drops," or "Find a way off the Titanic." It'd be fun and educational.
Basically, it's the wormhole theory of time travel. You create a wormhole, one end on Earth, the other being carried by a ship going near the speed of light. When the ship stops, it's one hundred years in the future, but the wormhole it's carrying still leads to Earth from where it left. All of a sudden you have a time machine that allows you to travel from when it was built to one hundred years in the future.
Of course, this theory requires wormholes to exist, and to be somehow transportable by human methods, and any number of complications. And it could very well still be completely impossible. However, it does posit a system where the time traveller cannot go further back than the creation of the time machine, for a logical reason.
Basically what I'm saying is that while time travel may very well be impossible, a lot of the common logical objections against it may be irrelevent since the "can't go back past the creation of the time machine" idea is at least theoretically plausible.
TIME DOES NOT WORK THAT WAY.
Neither does physics, or science in general.
Um, actually, it does. There is nothing in our modern understanding of physics which would preclude us from logically creating a wormhole, taking one end and zooming around the galaxy really fast, and then returning. When you returned the other end of the wormhole would still be in the past, at the point in time at which you left it.
The problems with us ever realizing this goal are manifold, but they're ones of practicality. We would need an insane, insane, insane amount of energy to open and sustain a wormhole, and we would need it in a form hitherto undiscovered. The equations say that it IS theoretically possible, however.
Okay.
I'm mainly running on what I've read about Kip Thorne's stuff on the subject here, but I'm not going to pretend I have enough grouding in it to argue the point properly. Still, do you mind commenting on what exactly about it doesn't work?
Because if Time Travel were physically possible, and it isn't, it would be possible whenever conditions were similar to it being possible, not just because it's discovered. That's an arbitrary boundary. If it were possible, and it isn't, then what if some race on the other side of the galaxy had already discovered it? It would be possible here. It would also be possible if no other race had discovered it.
SPIRIT NUKE! SPIRIT NUKE!
Seriously though. Maybe there's no time travelers because people in the future fucking know better than to mess with the past and risk screwing EVERYTHING up?
Thus, we have no (human) time travellers popping up around here because no-one has built a time travel device yet (around here at any rate)...
This does not however preclude the possibility of time travel being developed by someone else at some point, someone who might not have any interest in Earth's history because they have never heard of us.
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well this IS the internet.
He thinks channeling light through a medium is equivalent to lowering c itself. It doesn't fucking work that way.
I was like "okay, he's just one of those fringe theory people" until I got to that part. He absolutely should not have a Ph.D in Physics if he thinks that.
The more I read the more I realize that they'll give just about anyone a Ph.D just to get rid of them.
On the other hand, would someone like to explain why channelling light through a medium wouldn't slow it down? Or did someone actually try to change a universal constant?
Nintendo Network ID: AzraelRose
DropBox invite link - get 500MB extra free.
I was in no way condoning the idiocy of the OP's links.
I was explaining the views of many modern physicists.
There is nothing that theoretically prevents the construction of a time "machine" in the form of a wormhole. There are many reasons why we won't be able to build one, but there's nothing that theoretically prevents it.
And c of course is usually called "the speed of light" but what it really is is "the speed of light in a vacuum" and of course it also controls all kinds of other things like like the propagation of forces and whatnot, which unlike photons I'm pretty sure don't change speed in a medium.
Don't photons mediate the electromagnetic force?
I've actually never heard about this specifically, so maybe that means something other than what I thought it means. I am on uncertain ground.
Edit: And of course phase velocity vs. group velocity stuff
I think the point is that you need a receiving technogadget unit this end.
You know... the same way you couldn't hear radio signals by inventing and building one radio. You needed at least two.
This actually has to do with the definition of time too. Whether the past is the past and has happened, the present is the present and is currently happening, and the future is the future and has not yet happened, or if the past, present, and future are all currently happening at the same time, and we're only viewing the part we exist in. If the former is true, time travel isn't possible. If the latter is true, as soon as you build the device in the present, the future has the device too, and it can be used instantly, to even travel into the further past and deliver another unit.
I.E. Bob goes back in time to 1990, two universes are split, one in which he made it back, and everyone learns about time travel, and one (which we currently exist in) where he failed to make it back, or landed in a vacuum and died without a trace.
I don't think my, or anyone else's here for that matter, knowledge on the subject is as good as that of the Ph.D. dude.
While having a Ph.D. doesn't necessarily make him an all-knowing expert, it makes him a much more knowing expert than any of us, and he no doubt has heard the sorts of criticisms and opposition we are voicing here a billion times.
What I do know is to never call a scientist nuts. Remember the whole Galileo thing? "omg he thinks the world revolves around the sun lol"
This whole discussion reminds me of what Shinto said a while ago, about a bunch of non-experts arguing about expert subjects and that being a good definition of these forums. Not that that's a bad thing.
In any case, the person who manages to accomplish time travel, or anything groundbreaking for that matter, will be viewed with contempt and mild amusement until the very moment he accomplishes it.
Er, well I was mostly thinking of whatever mediates the strong and weak nuclear force. And the graviton. Assuming it exists. All those move at c, right? And I doubt they slow down in a medium. Especially not the nuclear forces, I'd imagine, since they're smaller than any possible medium
I might just be confused.
Time travel as achieved by wormholes etc. doesn't necessarily have this pre-requisite since you can create the wormhole in the future in such a way that it loops into the past. However on further analysis of techniques like this, it does seem to indicate some sort of chronological protection at work in the universe, in that a lot of them seem conceptually possible but then you get down and simulate the fine detail they collapse just before coming together - i.e. the universe may be suitable for life specifically because you can't do time travel in it, or something similar.
Edit: The rest of his stuff might be fine, but talking about how you're fighting the established science community and then making a fundamental error like that, well, it's pretty dumb.
Ah. OK, thanks
The problematical nature of photon spin
It kind of does, actually. I mean, Snell's Law is a byproduct of light being actually different speeds within different media, and if you manage to get a particle faster than the localized speed of light, you get Cherenkov radiation, which is weird shit.
I've never had anyone actually explain why light slows down in media, but there's more to it than you might think.
http://en.wikipedia.org/wiki/Refractive_index#The_speed_of_light
And saddam_whatever mind actually explaining that link? I can't be arsed to wade though it and all the follow ups.
Dramatization:
"We don't talk about that," the professor said coldly, narrowing his eyes on me. "And you," he emphasized the word, thrusting a pudgy finger at me, "won't either." He collected himself and put his hand palm-down on the table. "That is, not if you want to pass this course."
Afterwards, I overheard him in the teacher's lounge. "I doubt we'll have any more problems with Mr. Hoston," he cackled loudly and very sinisterly. His remark was met with much hooting from the entire gathered scientific establishment. "No, I solved that problem. Inform the Overlord!"
Realizing their plot, it dawned on me that I could not sit idly by and allow the conspiracy to continue. I must major in French literature and write about physics on the Internet.
I'm not buying it.
As I understand it - granted, I only learned about this one is a very introductory physics course, so it may not be entirely true, or even inherently flawed, like a lot of what I learned in that class - the reason light slows down in a medium is because the photons are absorbed by particles - say, an electron - and then spit back out a bit later as the particle returns to a lower energy state.
I mean, unless we're talking about gravity, a media doesn't really distort the world around it to make light go slower. Media are still mostly empty space (how would you define a medium?). So, if that class was correct, the individual free photons are still always traveling at c, but the net speed of the light is reduced because the photons are being constantly stopped by the particles of the medium.
I seriously doubt a professor would act that way, is all.
I would *guess* that the Snell's law process would be related to the interaction of the electromagnetic field of a light beam with the stationary fields of the material it's passing through, because you're right, matter is mostly empty space under one assumption, but that space is actually most definitely quite full of electric and magnetic fields from atoms.