Time travel paradoxes

[Angilion]

If you have something travelling at the speed of light, and you have something with in that object move forwards. Then that would essentially be travelling faster than light.

Saw it on a TV program about Stephen hawking theories

On that basis, we encounter things travelling faster than "the speed of light" all the time.

For example, I have two lamps in this room. Each is emitting light in all directions. They're not in the same place. There is, therefore, some light travelling from lamp A in the direction of lamp B and some light travelling from lamp B in the direction of lamp A, i.e. there is light travelling in opposite directions. If two things are travelling in opposite directions, then their speed relative to each other is the speed of each added together. So by that argument the light from each lamp is travelling at twice the speed of light.

But that's not how it works. It appears that c is a fixed limit, regardless of frame of reference. It appears that if you were travelling at almost c in one direction and I was travelling at almost c in the other direction, then we would perceive each other as approaching at almost c, not almost 2c.

It's like the old question of "if you were in a spaceship travelling at the speed of light and you turned the headlights on, what would happen?" The answer is weird.

 

[Robosapien]

This one's easy. No you wouldn't disappear. You'd just create alternative history. Ta da!

Having that sort of 'joined up' notion of time is just dumb.

 

[Infidelus]

The Vulcan Science Directorate has determined that time travel is impossible.

Someone should have told Spock that then before he successfully achieved "Time Warp" in Star Trek IV (twice)

 

[Duff-Man]

Someone should have told Spock that then before he successfully achieved "Time Warp" in Star Trek IV (twice)

They did. That was back in Star Trek: Enterprise

 

[One]

It's a known fact it's possible to manipulate the time-space continuum. The only issue is how to manipulate it, and what sort of energy would be required. Particles can disappear and reappear elsewhere quicker than they can physically travel there, one day we will learn how to control this.

 

[Amleto]

If you have something travelling at the speed of light, and you have something with in that object move forwards. Then that would essentially be travelling faster than light.

Saw it on a TV program about Stephen hawking theories

That is exactly how it doesn't work...

 

[mrk]

Killing your mother might mean you simply spawn a new timeline in new universe using the multiverse theory where every action causes a new timeline to branch off from that point onwards leaving the original timeline to never be altered!

Any other way would mean that the timeline is predestined, which it isn't. Given that thought, a new timeline would have to branch off surely? (if backwards time travel was even possible ).

 

[JBod]

I like the theory that no matter what you do you won't be able to kill your own mother because it never happened. There'd always be something that prevents you from doing so.

 

[Angleboy]

Traveling backwards in time is not directly possible - bar gathering information on the complete quantum state of every single fundamental particle in a given area - and additional info for the surrounding area - which would be very, very large - and inverting their complete, collective energy state for a length of time equal to the amount that the observer wishes to go back.

As well as removing particles as they hit zero-point state without interfering with the rest of the area concerned, and adding/removing particles that would have entered/exited the area as it 'rewinds' - including a "quantum clone" of your self.

If you then killed your mother, and proceeded to speed the areas rate of time, making everywhere else slow down relative to that area, up to the point where the area is back at the original point. You would have achieved the following:

Killed your mum.
Created and destroyed a clone of yourself and possibly many other things during the rewind process.
Still be alive.
Most likely wanted for murder.

 

[boxman2000]

I don't think killing your lineage will cause you to vanish all sci-fi style. I think if that scenario were to physically happen, travelling back in time would be impossible if not already.

You couldn't travel back in time to kill your mother as you wouldn't have existed to travel back in time to kill your mother in the first place.

Plus, you don't have a flux capacitor

 

[Ceryndrion]

Can't we just forget all this malarkey and concentrate on building a moonbase instead?

 

[spankingtexan]

You couldn't travel back in time to kill your mother as you wouldn't have existed to travel back in time to kill your mother in the first place.

Plus, you don't have a flux capacitor

Maybe I don't have a flux capacitor but me mates coming round with his club book, he says they sell em

 

[Ceryndrion]

Oh, and killing yer mother, makes no difference, you were adopted...

 

[crinkleshoes]

The speed of light can't be broken though.

No - but certain rules could be twisted in such a way as to make it appear to an outside observer that you have moved faster than the speed of light

 

[starfighter]

Time travel forward is possible already but we will never be able to travel back imho. So we can't create these paradox.

 

[Joshct]

What if i time travel'd forward, then got future me to kill me...

 

[Feek]

What you lot are stumbling towards are the details on how time travel may take place...

So you've got your early days "time machine", you sit on it, it's got cogs, all very steam punk. Importantly, the machine goes with you, so you need to have built it to get there and back.

Then you've got your new age "time machine", so very DeLorean. Many argue that this wasn't better than the original machine mainly due to the rarity of flux capacitors, but white haired gull wing door fans are adamant this is the best method.

Then you've got your "space-time tear gun". Warping the fabric of space allows you to effectively jump into a different time. Although you do run the risk of jumping into and/or creating a different space tangent, effectively isolating any causality issues for your original space-time continuum, making this the preferred method for the causality conscious of modern day time tourists.

Very Douglas Adams ish, I like.

 

[Confused]

What you lot are stumbling towards are the details on how time travel may take place...

So you've got your early days "time machine", you sit on it, it's got cogs, all very steam punk. Importantly, the machine goes with you, so you need to have built it to get there and back.

Then you've got your new age "time machine", so very DeLorean. Many argue that this wasn't better than the original machine mainly due to the rarity of flux capacitors, but white haired gull wing door fans are adamant this is the best method.

Then you've got your "space-time tear gun". Warping the fabric of space allows you to effectively jump into a different time. Although you do run the risk of jumping into and/or creating a different space tangent, effectively isolating any causality issues for your original space-time continuum, making this the preferred method for the causality conscious of modern day time tourists.

There's also the Crime Traveller style time-machine.

 

[Feek]

Can't we just forget all this malarkey and concentrate on building a moonbase instead?

There's no point, the moon gets torn out of Earth orbit along with Moonbase Alpha in 1999. I've seen the documentary.

 

[ChrisJSY]

But that's not how it works. It appears that c is a fixed limit, regardless of frame of reference. It appears that if you were travelling at almost c in one direction and I was travelling at almost c in the other direction, then we would perceive each other as approaching at almost c, not almost 2c.

The speed of light in other mediums not a vacuum has been broken (but still not faster than c), but that's as far as I'm capable of going with this sentence.
Then again, I may not be understanding a couple of things such as phase velocity.

I wonder how this will all play in the future.