Is it Physically Possible to Travel BACKWARDS in Time?

[Annapolis]

Atomic clocks are still subject to the laws of physics, and that experiment is largely flawed due to the atmospheric interference of space and our upper atmosphere.

The only way they would be able to conclusively prove time dilation exists is by having two perfect vacuums (which don't exist) and then using a device that actually measures time in a non rate-of-change sort of way.

We have no method of 'measuring time' without using the rate of change of a physical object we created. Even atomic clocks are subject to the duress of atmospheric pressure, especially when flying at high speeds in the upper atmosphere.

- G forces
- Vibrations
- Solar flares
- electromagnetic energy
- space debris impact

So until you can eliminate all those factors, you will not get an accurate reading on an atomic clock at high speeds.

I don't really know who told you that time dilation was still "up in the air" to physicists, but the field is so far beyond accepting time dilation as true that I don't really know where to begin. In essence you're denying that Einstein's relativity constant is actually in effect ever. If you read his paper "on the electrodynamics of moving bodies" you'll see that the theory was developed because of an innate paradox without taking into considering the effect of relativity. The paradox involves electric and magnetic forces in different reference frames. His proof works with force dilation and others but you can't have force dilation without time dilation.

Also, if time does not exist then what are we measuring with our watches and clocks? Sure we invented units for time and ways to measure it, but there has to be something there originally to measure that separates occurrences of events.

[Prokne]

Atomic clocks are still subject to the laws of physics, and that experiment is largely flawed due to the atmospheric interference of space and our upper atmosphere.

The only way they would be able to conclusively prove time dilation exists is by having two perfect vacuums (which don't exist) and then using a device that actually measures time in a non rate-of-change sort of way.

We have no method of 'measuring time' without using the rate of change of a physical object we created. Even atomic clocks are subject to the duress of atmospheric pressure, especially when flying at high speeds in the upper atmosphere.

- G forces
- Vibrations
- Solar flares
- electromagnetic energy
- space debris impact

So until you can eliminate all those factors, you will not get an accurate reading on an atomic clock at high speeds.

Any exterior forces that affect the decay of atoms in an atomic clock are taken into account when it calculates time. The experiment isnt flawed at all ad if you wanted to you could put an atomic clock in geosynchronous orbit and have another orbiting at the same altitude at a very high speed and get the same result.

[Deleted]

How can you time travel if there isn't time?

[Prokne]

Wow, when you have no facts, I guess straw men and ad hominem attacks will suffice, amirite? The relevant facts are that general relativity makes assumptions about the universe that observed testable facts don't jive with. Such as the famous Fizeau experiment. Not only that, but gravity doesn't create work. If it's a force, a la F=M·A, then it should add work, according to Newtonian physics, correct? Gravity doesn't add work, so it's outside of our ability to quantify. Fg=G(m1m2/r^2) isn't actually a constant, it's a working model; iron for instance seems to decline gravity in a local system.

Go read a physics primer. It will tell you we know nothing about gravity; and as crazy as it seems, I'l go with Bohr, Lawrence, and Planck when it comes to the provable science behind time travel.

Force does not mean work. Work=F X D where force and distance are vectors. If the force is perpendicular to the direction of the movement then no work is being done. This applies to an object orbiting another at a constant distance.

In another scenario two objects are placed a certain distance apart and in the absence of other forces they will attract each other because of gravity and move towards each other - work being done.

Also every part of relativity that we have the technology to prove has been correct so your statement that observable facts dont jive with it is false.

[tenzing21]

I don't really know who told you that time dilation was still "up in the air"

Ad hom attacks or rebuttals, are not actual rebuttals. It doesn't matter if the Easter Bunny told him time dilation doesn't occur. Either time dilation occurs as posited, or it doesn't. The source of the info is irrelevant to scientists. Lay persons might get their panties in a bunch if it doesn't come from Physics Today, but who cares.

The field is so far beyond accepting time dilation as true that I don't really know where to begin.

Fallacy of thought in that the listener is in love with the source. A Physics primer will explain to you, all we have is a constantly changing understanding, and no one is interested in how you personally think. At least not in so far as asking a university to grant them access to their lab based on your feelings.

In essence you're denying that Einstein's relativity constant is actually in effect ever.

Gasp, shock, horror... a free-thinking human being; whatever will we do?

If you read his paper "on the electrodynamics of moving bodies" you'll see that the theory was developed because of an innate paradox without taking into considering the effect of relativity. The paradox involves electric and magnetic forces in different reference frames. His proof works with force dilation and others but you can't have force dilation without time dilation.

General Relativity came into being to simply Michelson-Morley, and to showcase (what he thought was at least) a real-world application of Lorentz transforms . However, the Twin Paradox breaks down as soon as you realize that for an object A to be moving a rate of speed S with regards to reference point B, away from C, that that object C must (due to Lorentz Transforms and the Principle of Equivalence) be moving at the same rate of speed relative to B that A is. That's what general classical Newtonian physics realized through Relativity says. Which disproves time dilation.

Also, if time does not exist then what are we measuring with our watches and clocks? Sure we invented units for time and ways to measure it, but there has to be something there originally to measure that separates occurrences of events.

Um... I think that's what we're all saying; how do you prove this stuff??

---------- Post added 2012-04-06 at 05:00 PM ----------

Force does not mean work. Work=F X D where force and distance are vectors.

Sigh. A force is an observable phenomenon that has a physical effect on an object, to cause it to change a scalar, which in turn affects the vectors your mentioned. A zero sum force, still (and of course actually really and truly) does have observable forces on it. A body held captive in orbit around another celestial body, only exhibits zero sum force due to how the numbers are massaged. I guarantee you, that there is force on the Moon keeping you there, in stasis, that you can feel, use, and interact with wherever you are in the universe, that emanates from the Moon's mass. Were the Moon to crash into the earth, somehow, trust me those poor souls on whose home's the Moon landed would feel it's force, regardless of how many smart guys you stick in a room telling me there is a zero sum force at play.

Real world > fantasy.

[Prokne]

Sigh. A force is an observable phenomenon that has a physical effect on an object, to cause it to change a scalar, which in turn affects the vectors your mentioned. A zero sum force, still (and of course actually really and truly) does have observable forces on it. A body held captive in orbit around another celestial body, only exhibits zero sum force due to how the numbers are massaged. I guarantee you, that there is force on the Moon keeping you there, in stasis, that you can feel, use, and interact with wherever you are in the universe, that emanates from the Moon's mass. Were the Moon to crash into the earth, somehow, trust me those poor souls on whose home's the Moon landed would feel it's force, regardless of how many smart guys you stick in a room telling me there is a zero sum force at play.

Real world > fantasy.

You need to re read what I wrote. I said force exists even if there is no work being done as is the case with an object in a constant orbit. It was a response to something you said which was "gravity does not do work" and also "if its a force it should add work." The fact is that gravity is a force and can do work but doesnt do so in all circumstances.

A body held captive in orbit around another celestial body, only exhibits zero sum force due to how the numbers are massaged.

An object will maintain a steady orbit as long as its centrifugal force created by its tangential motion to the orbited body is equal to the force of gravity. For a circular orbit it can be simplified as Gm1m2/r^2=m2v^2/r. Both forces are equal so there is no change in r. There is no "massaging" of numbers.

[Annapolis]

Ad hom attacks or rebuttals, are not actual rebuttals. It doesn't matter if the Easter Bunny told him time dilation doesn't occur. Either time dilation occurs as posited, or it doesn't. The source of the info is irrelevant to scientists. Lay persons might get their panties in a bunch if it doesn't come from Physics Today, but who cares.

Fallacy of thought in that the listener is in love with the source. A Physics primer will explain to you, all we have is a constantly changing understanding, and no one is interested in how you personally think. At least not in so far as asking a university to grant them access to their lab based on your feelings.

Gasp, shock, horror... a free-thinking human being; whatever will we do?

General Relativity came into being to simply Michelson-Morley, and to showcase (what he thought was at least) a real-world application of Lorentz transforms . However, the Twin Paradox breaks down as soon as you realize that for an object A to be moving a rate of speed S with regards to reference point B, away from C, that that object C must (due to Lorentz Transforms and the Principle of Equivalence) be moving at the same rate of speed relative to B that A is. That's what general classical Newtonian physics realized through Relativity says. Which disproves time dilation.



Um... I think that's what we're all saying; how do you prove this stuff??

To your first point, I think the context of where the information comes from is important in regards to physics ideas. If a physics researcher or professor says something about a physics topic I'll pay more attention to their opinion than a person not involved as directly in the physics community.

It's true that we have a constantly changing understanding, but that doesn't allow for ignoring basic principles in physics. Are you suggesting F=ma is a matter of opinion too? It's nearly as equally fundamental.

He is free-thinking, but in the way that ignores available information. Anybody can say Einstein is wrong but to say it without considering the available information and ignoring facts is kind of pointless.

I'm going to assume you read the general relativity paper I guess by your last comment. The paradox he solves in the paper has nothing to do with the twin paradox. The twin paradox isn't even a paradox in the eyes of relativity really. The paradox is a disappearing force when you shift your frame of reference to one that follows the flow of electricity in a circuit or wire. Clearly either you didn't understand the paper or just didn't read it, I'm not sure which. You aren't arguing against Einstein saying that a twin will be younger if he travels faster than his brother, you are arguing against Einstein's ability to show that when you change your frame of reference relative to electricity, forces don't magically disappear. So basically by saying time dilation doesn't exist you are more ready to believe that a wire can move spontaneously with no forces. That is how fundamental relativity is.

Do you have a better explanation than the paper for why a wire would seemingly move without a force acting on it? Or should we just assume that Einstein's widely used and experimentally supported equations are wrong and we just don't know yet?

[raintrees]

ya totally, just grab yourself a TARDIS

[baowolf]

Despite what Doctor Who fans would like to believe, our understanding of time is that it's linear and unidirectional. Translation: you can only go in one direction. Time-travel, and dilation, and all that, is all about accelerating the passing of time... still in that one direction.

To answer your question, no.

Also, flying west doesn't count.

Ok first off time is not linear, that's just how we see it. If time was i linear progression of events then all things would be happening at the same time, which is not the case. example is doesn't mars the same amount of time to orbit the sun as it rakes earth. This is why time is "relevint"(think i miss spelled that) to its self. It is better to say that time is more like a giant slider wb in which each stand is connected to each other. This is why the simplest of evens could change the future other wise it wouldn't matter what any pine did at any point the future would always remain the same. Which in turn means that when something happens it is as it was "planned" to be.

Second to say that time travel is impossible because physics says so is just plain silly. Hate to bring this up but you ask leave me no choice, out was not that lung ago that science said the earth was flat, and it want that long ago that physics said we could never get to the Moon, and just what do you think science would say if you went back in time even 50 years and told them about any of the tech we have now.. To say that so can't be done just because any one says do is silly, i don't care who it is that said it.

To answer your question the best possible way, in fact the only real answer possible. Yes and no, until some one either goes back in time physically and can prove it beyond any doubt or until it is proven beyond any don't that it can not be done, then like the cat in the box it is both possible and impossible. And in sorry but a few math equations do not prove it either way, three only way to prove it can be done is to attempt every possible way of doing so and every attempt to fail. Simply put you can show me 1000 equations that say it can't be done and i can show you 1000 equations that say it can be done. Physical prove is the only real prove.

Sorry about the mistakes i wrote this with my phone which doesn't like to make a lot of sense all the time, sorry.

[tibe]

Actually, it wouldn't. Space's expansion (or contraction) does not dictate the flow of time.

Unless maybe space were to contract to a size of 0 units and there was no "place" for time to pass, I guess, maybe.

That's funny, because from the little I know; a black hole actually means a space-time distortion. And I'm pretty certain I read something about time not flowing "like we know it" around black holes/white holes.

[Lagwin]

What about just creating a different parallel universes, like String theory suggests? (infinite universes)

That's how i think it would work, you can go back but it wont effect anything in this timeline as you'd be in a different reality.

[Dezerte]

I always imagined time travel into the past may be possible, if by time travel you mean going into a different universe (multiverse hypothesis) and thus will not affect the current universe.

[Rinoa]

I'm not going to delve into this debate, but I do want to ask if there are anyone here that can answer a question I have.

In a Q&A session of an interview Dr. Neil deGrasse Tyson did, he said that it was possible to take a very specific route in between two colliding black holes that would make you travel back in time to before you started your trip. It'd most likely kill you, but he did say it was possible. Does anyone have an explanation for this or was he merely joking?