is time travel possible?

[Live702]

Couple questions:

1. Math isn't quite my strong point but... Doesn't dividing by 0 give you infinity? if this is the case would your density tend to be near that and wouldn't that be bad, like universe collapsing in on itself bad?

2. I have heard theories composed of taking two wormholes (if they were able to be handled) and using the space-flight example and creating one that goes farther into time than the other thus creating a time travel device. But as the one returns the whole thing destabilizes and collapses. Does anyone know why this is?

3. Has anyone heard theories that wormholes do exist on a very small level in the spaces between quarks? It's based on some type of quantum foam idea.

[Mr2Spyder2828]

In physics there are some equations dealing with relativaty and they state that if you could move away from the earth at a speed close to that of the speed of light which is 3 times 10 to the 8th power m/s then you would age slower than those left on earth. speed of light=180,000miles/sec.

Since gravity can curve space, general relativity allows the possibility of shortcuts: wormholes. Worm holes are taking an object and moving it at .9999999999 times the speed of light, in a circle. Time will move very slowly here. In the future anyone entering the wormhole can come back in time to when the wormhole was created. But you cant go back in time to a point before when you built the wormhole!

Though it is not practical with current means to build a wormhole. There are solutions of the equations of general relativity that include them. In principle, one could be made, but its not going to be easy.

If someone was in a space ship and moved away from earth at a speed of .995 times the speed of light. then 10 years pass on earth, only 1 year would have passed on the space ship.

When moving near the speed of light distance appears to shorten. Called length contraction. Those traveling in the ship moving near the speed of light would see everything around them shrink. The earth and moon would apear oval and would be close together.

[loismustdie]

i'm not trying to insult you...........

and from what i've read, this is what you've said: "time travel is not possible in our world, but in theory it is possible" i know this is not what you meant but thats what i've interpreted so far, and what debate could there be. i mean the fact is the only kind of time travel possible is time dilation. so whats there to debate?

[loismustdie]

and the whole thing with aging only 1 year when it ages 10 on earth, this is not time travel anymore than aging 10 years.

[Joseph1082]

That's exactly what I am saying... we are barely intelligent enough as a species to even begin to grasp what we are talking about... so in our world, it is not possible. Alexander the great conquered "the World", an area roughly the size of the United States. Imagine in the future how our definition of "the World" might change. For right now it is outside of our understanding. We haven't even considered the possibility of other dimentions. We are only operating in 4 right now, but scientist say there are at least a few more. The secret could line in the properties of these higher dimentions.

[moslerporschefreak]

Interesting to have some more intellectual conversation here. Anyways, loismustdie, what is your theory about restarting time?

Also live702, in math at least, dividing by zero doesn't yield infintiy. It is an inditerminate number, that is not the same as infinity. Basically, we don't know what anything divided by zero is (there is no limit or near comprehension of it either, we simply don't know). I assume this principle translates into physics, but I could be wrong...

[Joseph1082]

And as for the 1 year, 10 year thing, that is up in the air. If I was cryogenically frozen for 100 years and then awoke, to me it would be the same as if i stepped into a time machine and sent 100 years into the future. This kind of "time travel" works because it is in the same direction as the flow of time, it is easier to paddle down a river w/ the current than against it, hence the difficulty in going backward as opposed to forward, the easier of the two. This comes down to what is your definiton of time travel... we "time travel" every second of every day. I guess you could say there is no such thing as "time travel" persay, but what we are discussing is the possibility of changing the velocity at which we time travel.

[Joseph1082]

Dividing by 0 can be interpited different ways. It CAN be considered infinity. It also can be an instant, such as at t=26, Velocity=100, then also at t=26, V=120, acceleration, change in Velocity over change in time, denominator is 0. this can considered an inifnite acceleration, or a completely instanteous one. Both do not exist as far as i know.

[moslerporschefreak]

I thought that there would be a different interpretation of this concept in physics. But strictly speaking (mathematically that is), dividing by zero is not infinity or indeterminate. But since we are talking about physics, that point is relatively pointless (no pun intended)

[Joseph1082]

Dividing by zero is infinity in Calculus (Math) as well as physics. If a function is y = 1/x, let's say. At x=4, y=.25... correct. so in terms of the functions limits, as x tends to 1, y tends to .25. If x=some really small number, then y=some really large number... correct so far. So as x tends to 0, y tends toward infinity. If x is negative, same conditions, y tends to negative infinity. No negatives in the real world, beside, whether positvie or negative it is still infinity. The solution is: the limit of y = 1/x as x approaches 0 from the positive side of the y-axis is positive infinity, and as it approaches 0 from the negative side, the limit in negative infinity.

[Joseph1082]

any number/0 is undifined, the indeterminant is 0/0...
0/x is zero
x/x is one, the identity
x/0 is infinity, undifined, whatever
so what is 0/0?

[burnM]

Are we not effectively travelling through time right now?

[deadlight]

www.johntitor.com

Just thought I'd throw that out there if there were people here who'd seen it. Even if you don't believe the story it has a lot of information on the physics and mathematics involved in time travel. Good read.

[Mr2Spyder2828]

I am taking a physics class right now and we are talking about relativity. Thus, we are talking about time travel and if it is possible. What I have said in my last post is what we know is possible. Theoretical physicists have came up with these equations and theories and I think I would believe them over anyone else. Time travel is possible considering on how you interpret time travel. There is no room for debate once you understand the relativity theory behind it.

So the answer is ...
1) Going forward is not big deal; happens all the time
2) Going forward and not aging is possible but not practical (energy!!)
3) Going forward and backwards can be done if there are wormholes
(certainly impractical!!)

[Joseph1082]

That is exactly what i have said in my many posts, just in more simplified terms. Also, since we have no clue about the universe, what if the are regions of space-time where time is different from here on earth... say a place somewhere where one year passes, 19 pass on earth. some twisted pocket of the space time continuum. We know time is not the absolute in the universe, c is. Just mental candy here. Also, from a philosophical point of view... can we every really go back and change time, becasue even if we could, we would still retain memory of all the events and therefore the change would not be complete... so I'm sure philosophers would say that what's done is done, and cannot be changed.