If time travel existed...

[txrandom]

Someone explain relativity in respect to time.

 

[Vic]

The shockwave from a supernova travels considerably slower than the speed of light (roughly 0.03c), so we would see the event long, long before it killed us.

 

[jr22jess]

This is probably one of the deepset threads I've seen in a while but maybe it's as simple as the present is as far as it's ever gotten, looking at it as a time scale, and the technology we have yet seen and experienced to date is nowhere near enough to what it needs to be. Only then in the far far future will we find this out. We just haven't made it there yet. BTW I don't believe in time travel.

 

[So]

Originally posted by: Vic
The shockwave from a supernova travels considerably slower than the speed of light (roughly 0.03c), so we would see the event long, long before it killed us.

I thought it wasn't the shockwave that kills us, I thought it was the gamma radiation (the bad non green lantern / hulk kind ) that would scan the earth like a death ray.

 

[TheSiege]

"They took our jobs!!!!"

 

[So]

Originally posted by: txrandom
Someone explain relativity in respect to time.

Wikipedia has a decent explanation. Basically, Newtonian motion was the realization that motion in space was relative - i.e. if you play catch on a train, the ball will appear to move a shorter distance to you than to them.

Einstein realized that we had intuitively NOT extended this to time, and considered the possibility that it did. When he realized that all light travels at a fixed rate, and considered the situation, he came up with what we call relativity. I suggest reading the wikipedia articles on special and then general relativity.

 

[destrekor]

Originally posted by: waggy

Originally posted by: destrekor

Originally posted by: So

Originally posted by: Rob9874

Originally posted by: DaShen
Looking back into time without traveling there can actually happen though. We do that everyday when we look at the stars.

Exactly. I think that's very interesting. When we witness a star dying, which is 300 light years away, we're witnessing an event that happened 300 years ago.

If someone 300 light years away had a powerful enough telescope, they could see events happening on Earth 300 years ago. Think about that!

see, but not hear. WTF would they think?

"Look at strange creatures that wear cloths and do strange work. Oog don't like that, Oog like to watch fire here by shore next to acid lake"


but seriously, wanna blow your mind? There is a star that is extremely large and powerful 1500 light years away that is on its last years of life, or cold already be dead. One that is powerful enough that the shockwave and heat from the supernova will wipe out everything within 100 lightyears from it, and depending on the situation we could see it in broad daylight with our naked eyes. We could just be playing catchup with the life and a blackhole could already have formed or be forming at its location as we speak.
Crazy eh?

this is why i hate these threads. i end up thinking about crap like this..sigh

i should correct myself. I was merely working off of my astronomer's words. It is actually less than 500 light years away, and is actually named Betelgeuse (Alpha Orion), the brightest star in the Orion constellation, 9th brightest in the sky. It's in the same 'wing' of the galaxy as our solar system, and if it were to be placed where our sun is, its outer edges would be near Jupiter. But its also only 20 solar masses, so its size to its mass makes it quite the opposite of the word dense.

 

[Matt2]

Originally posted by: DaShen
Proof for you guys

bwhahaah!

That was hilarious.

 

[Vic]

Originally posted by: txrandom
Someone explain relativity in respect to time.

I already did. All objects move through spacetime at speed c. The more rapid the movement through the physical dimensions x,y,z, then the slower the relative movement through dimension t, and vice versa. Massless photons of light travelling through space at c do not experience time. We experience time at our own relative speed because of the movement of the earth around the sun and the movement of the sun around the galactic center, etc.

 

[AkumaX]

If i was a time traveler, i'd strike down French Stewart. What's he squinting about??

 

[So]

Originally posted by: AkumaX
If i was a time traveler, i'd strike down French Stewart. What's he squinting about??

He was trying to look directly at your mother's face.

Oooh, burn!

 

[Vic]

Originally posted by: So

Originally posted by: Vic
The shockwave from a supernova travels considerably slower than the speed of light (roughly 0.03c), so we would see the event long, long before it killed us.

I thought it wasn't the shockwave that kills us, I thought it was the gamma radiation (the bad non green lantern / hulk kind ) that would scan the earth like a death ray.

 

[Matt2]

Originally posted by: So

Originally posted by: TheSiege
ok so since i am new to this, how fast can a space traveling object move? in theory what results could we see right now if someone was to attempt this

Pretty simple really:

According to relativity, we can approach infinitely close to the speed of light but not reach it, and the more you accelerate, the more energy you need. Additionally, space is not a perfect vacuum. Even in intergalactic space, the universe it permeated by a tenuous (1 atom in hundreds of cubic kilometers or something) hydrogen gas. So, we could accelerate very, very close to C if we had enough energy. With technology today, we can't even go .01% the speed of light, but with very accurate clocks, we HAVE tested it, and the results have perfectly matched the theory's predictions.

Edit: One of the fastest designs yet conceived, the Bussard ramjet (still completely impractical to build) might be as fast as .16C

I saw on the news somewhere that we had the technology to use anti-matter (no not like Star Trek) to reach the nearest star in 26 years. But 1 gram of anti-matter cost billions to produce and we would need a lot.

I dunno, maybe I dreamed that up.

 

[joecool]

posts to this thread can be divided into two categories:
1) for some unknown reason, take the op's question seriously, and make up a bunch of sh*t about why it can/can't work. most of these posters have no idea what they are talking about, and mutilate various laws of physics to "prove" their points.
2) understand what a silly question this is, and respond with humor.
I'll take the posts that fall into category 2 - very funny!

 

[So]

Originally posted by: Matt2

Originally posted by: So

Originally posted by: TheSiege
ok so since i am new to this, how fast can a space traveling object move? in theory what results could we see right now if someone was to attempt this

Pretty simple really:

According to relativity, we can approach infinitely close to the speed of light but not reach it, and the more you accelerate, the more energy you need. Additionally, space is not a perfect vacuum. Even in intergalactic space, the universe it permeated by a tenuous (1 atom in hundreds of cubic kilometers or something) hydrogen gas. So, we could accelerate very, very close to C if we had enough energy. With technology today, we can't even go .01% the speed of light, but with very accurate clocks, we HAVE tested it, and the results have perfectly matched the theory's predictions.

Edit: One of the fastest designs yet conceived, the Bussard ramjet (still completely impractical to build) might be as fast as .16C

I saw on the news somewhere that we had the technology to use anti-matter (no not like Star Trek) to reach the nearest star in 26 years. But 1 gram of anti-matter cost billions to produce and we would need a lot.

I dunno, maybe I dreamed that up.

The numbers are off, but that's basically right. If we tried to make mass production facilities for antimatter we could lower it cheap enough to make it only mind-bogglingly expensive instead of uselessly expensive.

 

[zinfamous]

Originally posted by: So

Originally posted by: zinfamous

Originally posted by: Rob9874

Originally posted by: DaShen
Looking back into time without traveling there can actually happen though. We do that everyday when we look at the stars.

Exactly. I think that's very interesting. When we witness a star dying, which is 300 light years away, we're witnessing an event that happened 300 years ago.

If someone 300 light years away had a powerful enough telescope, they could see events happening on Earth 300 years ago. Think about that!

OMG! I just ****** my pants thinking about that.

Also, I think Deja Vu is evidence that we have all time-travelled, at some point, without ever knowing it. Future time travel people invented time machines for the express purpose of screwing with us past time people. What assholes.

:laugh:

I'm pretty sure you're joking, because my previous discussions with you have revealed your intelligence, but for people who don't know, Deja Vu is a reasonably well understood neurological phenomenon.

facetious indeed. I am serious (well, not literaly-wait, let me check...yeah, not literaly) about my response to the post quoted. That is a cool concept. I just wanted to make up some BS about deja vu b/c I felt like throwing deja vu into the discussion. should have made that in a separate post.

 

[ShadowOfMyself]

Ehm... No one answered my question yet I have no idea about physics so I wont pretend I know, but if things work like that... Ok lets picture something Ive always wondered:

Guy 1 is in spaceship at lightspeed, Guy 2 is on earth, they estabilish some form of comunication - what happens? Does Guy 1 see Guy 2 in slow motion? Do they see each other normally? Might be clueless but I really get all confused by this stuff

Oh and also, you say we are "seeing the past" when a star dies and we still see them in the sky... Well thats not true is it? You still see it because light is still travelling... Thats like saying when you hear a supersonic airplane, youre hearing the past, because the plane has already gone by and youre still hearing the sound... Get what I mean? Someone with knowledge clarify please

 

[DrPizza]

Originally posted by: joecool
posts to this thread can be divided into two categories:
1) for some unknown reason, take the op's question seriously, and make up a bunch of sh*t about why it can/can't work. most of these posters have no idea what they are talking about, and mutilate various laws of physics to "prove" their points.
2) understand what a silly question this is, and respond with humor.
I'll take the posts that fall into category 2 - very funny!

I'll take category 3: Those who understand that time travel is theoretically possible. However, it wouldn't be possible to travel in time back to before the machine was invented. Use google.scholar to hunt for more information if you're interested.

 

[HighPsi50]

Well to answer your question directly

If you could "see" into the ship moving at 99.999% the speed of light, the activities in the ship (clocks, people's movement, etc) would appear to be very very slow. The opposite would be true if you were on the ship looking at the earth. As far as relative perceptions, the ship would appear to be moving by you at 99.999c, whatever that looks like. But its appearance would be distored due to the relative time dilation between the two. The thing to get your head around is that in the physical 3D world, the speed of light is the speed limit, and it takes and infinite amount of energy to propel mass at that speed. Space is constant, speed of light is constant, the only thing left to change is the rate of the passage of time within the frame of reference of the moving object.

As for observations of star at distance, you see the star as it appeared when the light you are viewing left the star. If a star is 10 light years away, the light you see has taken 10 years to travel from the star to your eye. Thus the image shown by the light is 10 years old. The more understandable corollary would be that if a bomb were to go off a long way away from you and you heard the boom, you wouldn't hear the explosion at the exact time it happened, because sounds takes time to travel. Thus, you are actually "hearing into the past", as by the time you hear the explosion, it is already over. Light works exactly the same, its just not typically observable to us.

 

[Matt2]

So Spike TV plays a lot of Star Trek during the mid day and this conversation led me to watch a couple of episodes.

What's their theory on faster than light propulsion? I know in the show they can travel more than 9x the speed of light. Is that something that Gene Roddenbury pulled out of his ass and has no truth to whatsoever?

I dont watch Star Trek, but it seems to me that their (fantasy) propulsion system folds space around the ship allowing it to travel faster than light.

Just food for thought. It seems like we are thinking in one-dimensional terms saying that faster than light propulsion is IMPOSSIBLE when in reality our understanding of such things is so limited that it could be possible.

 

[SVT Cobra]

Originally posted by: So

Originally posted by: txrandom

Originally posted by: ShadowOfMyself

Originally posted by: txrandom

Originally posted by: ShadowOfMyself
Well, not exactly.. Remember we dont have time travelling devices yet, so if you travelled to the past you would be stuck there forever... Maybe they only travel back to the point where the first time machine was invented so they can go back to the future

What if the time traveler traveled to the past in a time machine that came with him. He should be able to go back to the future right?

I really have no answer for that, maybe its only possible to teleport organic matter... I have no idea lol

Btw since we are on this topic Ill take the chance to ask another question... When you are in space travelling at high speeds time goes by slower, right? So... If we had a lightspeed spaceship, and travelled in it for one year, when we came back to earth, people would have age much faster, right? Well, thats technically time travelling into the future or am I missing something?

This is something my Physics teacher talked about. I didn't understand how traveling faster makes time slower. Time is a human-defined constant. There is one second every second. If we walked on Earth for 1 year at 1 m/s and traveled in space at 3 * 10^8 m/s for 1 year, people on Earth would still be 1 year older.

I might be missing something obvious because I've heard this from other sources too.

You have no grasp of relativity whatsoever. I'm not trying to be offensive, and I'm sure you could learn it - you probably had a bad teacher, but you are absolutely, 100,000% wrong.

 

[Special K]

I will just add that anyone who is seriously interested in this topic should read Hyperspace by Michio Kaku. It does a really good job explaining relativity, higher dimensions, and other theoretical constructs like wormholes.

 

[So]

Originally posted by: Matt2
So Spike TV plays a lot of Star Trek during the mid day and this conversation led me to watch a couple of episodes.

What's their theory on faster than light propulsion? I know in the show they can travel more than 9x the speed of light. Is that something that Gene Roddenbury pulled out of his ass and has no truth to whatsoever?

I dont watch Star Trek, but it seems to me that their (fantasy) propulsion system folds space around the ship allowing it to travel faster than light.

Just food for thought. It seems like we are thinking in one-dimensional terms saying that faster than light propulsion is IMPOSSIBLE when in reality our understanding of such things is so limited that it could be possible.

It's utter bull**** that Rodenberry just made up - parroting his soft sci-fi predecessors like flash gordon. You just can't have a good space story based on just one planet. And our understanding of such things isn't so limited.