Time Travel Looks To Be Possible.

[washi me sensie]

I just want Doc. Emmet Brown to build me a "special" car.

ill second that! doc emmet's the man!! ill send a msg to marty mcfly later!

 

[Patient_Cero]

Depending where you live in this country you can easily drive an hour and feel like you stepped back 100 years due to lack of freedoms or common amenities. With regards to advancement in technology, our rate of progress has severely been hindered. The death of common sense alone has run rampant so advancing past the disease that is eroding that from everyday life will be a bigger accomplishment at this point.

 

[OakleyGuru379]

On a side note, where did you get your avatar pic? My girlfriend loves the "evil genius kitty"

 

[OakleyGuru379]

McFly?! Anybody home McFly?!

ill second that! doc emmet's the man!! ill send a msg to marty mcfly later!

 

[Sunglass Shack]

On a side note, where did you get your avatar pic? My girlfriend loves the "evil genius kitty"

Thanks, Google image search awhile back. It is also the business Facebook page picture.

 

[qtrain23]

You time travel every day. But only forward.

 

[WavecloudCustoms]

Time is actually omnidirectional and spreads outwards, from the centre (you, me, us) in every way possible.

Time is just a measurement of space - hence, Space time, and it is all happening at once. That concept is pretty huge for the human mind to grasp, though, so we as a society agree on a 'timeline' which moves forwards. It actually isnt really moving at all

Folk say to me "I don't know where the time has gone" and I say "It hasn't gone anywhere"

 

[kronin323]

Stumbled across this thread searching for something else and had to chime in...

I'm just a layman but I've been fascinated by physics for a long time, have a pretty good layman's understanding of the subject without any of the math. To be clear, not an expert, just an enthusiast...

So, the whole thing you're talking about is from Einstein's special relativity (as opposed to his general relatively, which is about gravity). It's based around the novel concept that light travels at a fixed speed, regardless of perspective. If you throw a 75 MPH fastball in an airplane going 300 MPH, the ball travels at 75 MPH relative to you, but at 375 MPH (if you're throwing it forward) relative to a person on the ground. But that doesn't work with light. The light from the headlights on that plane is traveling at the speed of light relative to a person on the plane, but it also travels at the speed of light relative to a person on the ground, NOT the speed of light plus 300 MPH.

That was radical thinking - historically the mindset was that our passage through time was at a fixed rate and everything else had to adjust to fit within that limitation. But by making the fixed datum the speed of light, suddenly time became a variable rate, and the math that theory generated allowed the making of predictions, testable hypotheses, and testing (such as that astronaut's watch thing) has proven its validity (the word "theory" means something quite different in scientific terms compared to common usage; a scientific theory has successfully withstood incredible amounts of testing designed to disprove it; common usage of "theory" more closely resembles the scientific term "hypothesis"). I could give a clearer example of how this variable-time thing works, but this post is overloaded too much already...

So here's something that can blow your mind - imagine there's a car that travels at 45 MPH and only 45 MPH, no time to accelerate from 0 to 45 or decelerate from 45 back to 0. That car's out on the salt flats and there's a start and a finish line five miles apart. You are an observer standing some distance off to the side, halfway between start and finish. If the car goes from start to finish in the shortest possible line (perpendicular to start and finish lines), you would see a car moving across at 45 MPH. But, let's say the car makes a second run at an angle, so when it hits the finish line it's half a mile to the left of where it started. To you as the observer from the side, the car would still appear to travel from the start to finish, but at a slower speed. Why? because some of that 45 MPH velocity is spent going sideways instead of forward, to take the angular route. So to you as the observer the car appeared to be traveling at two different speeds while in truth it was traveling the same speed both times, only the second time that speed was split between two spatial dimensions. Got it?

What does that imply? Well, with special relativity, when we increase our speed in any of the three spatial dimensions, our speed in the temporal dimension decreases (from the perspective of an outside observer). Like that car example, it's as if everything is traveling at a fixed total speed through all four space-time dimensions, and what can differ is how that total speed is split out among those dimensions. We're all traveling at the speed of light, just some of that velocity is diverted to our forward travel through time / the temporal dimension. Another implication? Since light has all of its speed traveling through the three spatial dimensions, it must has zero velocity remaining to travel through the temporal dimension (from the perspective of light itself, if it were a conscious observer)... Mind blown yet?

So, back to the whole time travel thing, we're all traveling through time. And, though we all experience that time travel at the same rate, the rate one observer travels relevant to another observer may differ depending on their respective velocities through the three spatial dimensions. But, unlike the three spatial dimensions, travel through time / the temporal dimension is only one-way; you can only go forward (the "arrow of time" is defined as moving from a state of order to disorder, i.e. a cup can fall off a table and shatter on the floor, but cup fragments on the floor cannot jump up to the table and form into a cup). Travel backwards in time, by our current knowledge, is impossible. Technically if one were to travel faster than the speed of light, they would travel back in time of sorts, but it is impossible to travel faster than the speed of light. You can't even travel the speed of light, only close to it - it would take infinite energy to accelerate matter to the speed of light (light itself is pure energy, not matter).

Besides, travel back in time would open the door to all sorts of paradoxes - there has been plenty of thought spent on ideas of backwards time travel that avoid those paradoxes, but it's really a moot point if it truly is as impossible as it appears to be in modern science...

Regarding that whole speed of light speed limit, though, you also have to consider quantum mechanics - Einstein's stuff accurately describes things that are large, quantum mechanics accurately describes things that are very small. And the two are completely incompatible. That's the Holy Grail of physics right now, a Grand Unified Theory that explains the behavior of the large and very small consistently.

In quantum mechanics, there are examples of information traveling faster than the speed of light, quantum entanglement being the most common example. Even the experiment that launched quantum mechanics shows some examples (that experiment is called the "two slit" experiment; get your mind out of the gutter... the two slit experiment is absolutely fascinating and it is said that all of quantum mechanics can be implied from the results of that one experiment).

Anyway, as hard as the whole fixed speed of light might be to grasp, quantum mechanics is the most counter-intuitive science out there - anybody who claims to understand it completely is a liar. I just bring it up to point out that, despite the limitations on time travel found in modern science, it's still possible that greater understanding in the future may change that. Or maybe not.

In conclusion, if any of you out there find this interesting, I highly recommend the book "The Elegant Universe" by Brian Greene. It's actually about string theory but over half of it is covering Einsteinian physics and quantum mechanics in order to give the proper context when you get to the string theory stuff. I found his explanations of various concepts for the layman to be better than anything I've run into before, even in school; very clear and complete:
The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory: Brian Greene: 9780393338102: Amazon.com: Books

Also, if anybody wants to ask questions about any of this post, I'd be glad to elaborate, if you think you're up for it...

 

[WavecloudCustoms]

I've read it twice!

Yep!!

I get the whole picture in my mind!

Explaining it to another person is another matter entirely

Lets chat....

 

[WavecloudCustoms]

Another book that's well worth looking at but much simpler is The Beginners Guide To Constructing The Universe..