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[Osmosis Jones]

What about for those who have done neither?

Hmm technically you could get away with decent high school maths and nothing else, the other stuff just helps.

I'm not convinced by that.  As I think my immediately prior message hinted at (without having read this first, sorry)...
...
edit: In a classic "message takes time to get somewhere" example, I think I've been replied to on a previous version of this point.  I'll look at the link in a moment, but I'm entitled to make myself look like a fool for the courage of my convictions, so I'll post anyway and recant at leisure if need be.

That's perfectly fine, you shouldn't just believe something without working through it yourself

Messages that "travelled back in time" are only 'seen' from frames of reference in which there are further SoL delays.  i.e. you can see a 'further away' destination receive a message before it should have done (by your frame of reference), but the time taken to be notified of that reception completely lags the message behind that which would have come directly from the initial sender.

And those sent from further to nearer could just have been sent straight to you, rather than stopping off at the nearer.  Rotating frames add other complications, of course, but a similar lack of advantage in all the variations I'm contemplating.

Yeah, that's a big issue, which is why I made sure to mention at least two receiver/transmitters being sent off. You can use those to ensure the correct frames of reference are obtained. However, point of interest; once you have a signal sent back in time to the original point, there's nothing stopping you looping it through again, and sending it back still further

The faster we can go over c, the easier it is to get sufficient relativistic differences between multiple frames of refence.

(BTW: "neutron sources"->"neutrino sources", yes?)

Herp a derp >.< Cheers for catching that.


GAH TOO MANY NEENJAS

Starver, on your latest post, the pertinent points are used to construct an example;

   

• As observers O and Op pass by one another (as they are shown in Diagram 8-1 ) Op uses some method to send out an FTL bullet from his reference frame. The event "O and Op pass one another" will be called the "passing event" from here on.
• The bullet strikes and kills a victim who's death is the event marked "*" in Diagram 8-1 . This event occurs after the passing event in Op's frame of reference, but it occurs before the passing event in O's frame.
• A third observer is at the victim's side as he dies and thus he witnesses the death. This third observer is stationary in O's frame of reference (i.e. his frame is the same as O's), so the victims death ("*") occurs before the passing event (when the bullet was fired) in this third observer's frame. Thus, the third observer has witnessed a result which comes from an event in his future--he has information about a future event in his frame of reference.
• The third observer sends this information about the future to O using an FTL signal, and in the third observer's frame of reference, O can receive this information before the passing event occurs (and thus before the bullet is fired).
• O receives the message and learns of the victims death before the bullet is fired. He thus knows about the bullet being fired--an event in his own future which will occur at his very location.
• O uses this information to prevent Op from firing the bullet, thus causing a self-inconsistent situation--an unsolvable paradox.
  

OH GODDAMIT MORE NINJAS

Yeah, Bremen gave a good example.

*twitch* ninjas *twitch*

[Loud Whispers]

GOD DAMN NINJAS TRAVELLING FASTER THAN MY NEUTRINOS.

[Osmosis Jones]

Has anyone figured out a way to harvest vacuum energy yet, so we can use it as a fuel source? You guys are all freakin' brilliant, it shouldn't take too long.

No, because it's impossible sadly Here's the thing, when everyone talks about using energy to do work, they all think that it's the absolute energy level that matters. It isn't, but rather the difference in energy between two points. The problem with vacuum energy is, although it is non-zero, there is no point of lower energy (by definition, it is the 'zero-point'). This means it is impossible to set up an energy gradient, which is what we need to extract said energy.

GOD DAMN NINJAS TRAVELLING FASTER THAN MY NEUTRINOS.

You neenja'd me -_-

[Loud Whispers]

Has anyone figured out a way to harvest vacuum energy yet, so we can use it as a fuel source? You guys are all freakin' brilliant, it shouldn't take too long.

No, because it's impossible sadly Here's the thing, when everyone talks about using energy to do work, they all think that it's the absolute energy level that matters. It isn't, but rather the difference in energy between two points. The problem with vacuum energy is, although it is non-zero, there is no point of lower energy (by definition, it is the 'zero-point'). This means it is impossible to set up an energy gradient, which is what we need to extract said energy.

GOD DAMN NINJAS TRAVELLING FASTER THAN MY NEUTRINOS.

You neenja'd me -_-

There's no such thing as vacuum energy, all we know is, vacuum is the fabric of space, with an absence of matter.

We have no clear idea what that is though.

Also, about energy.....

[Long story short, so many questions, too little answers]

[Bremen]

Has anyone figured out a way to harvest vacuum energy yet, so we can use it as a fuel source? You guys are all freakin' brilliant, it shouldn't take too long.

No, because it's impossible sadly Here's the thing, when everyone talks about using energy to do work, they all think that it's the absolute energy level that matters. It isn't, but rather the difference in energy between two points. The problem with vacuum energy is, although it is non-zero, there is no point of lower energy (by definition, it is the 'zero-point'). This means it is impossible to set up an energy gradient, which is what we need to extract said energy.

Can't you set up a vacuum energy gradient with the Casimir effect, though?

[thobal]

What about for those who have done neither?

The basics, as I understand it, are these:

According to special relativity, there is no "one" measurement of space/time that is correct. Instead, there are any number of reference frames.
Most importantly for this discussion, time is not universal in all reference frames; hence the phenomena of time dilation you've probably heard of.
However, time flows normally for each reference frame; if you fly away from Earth at relativistic speeds, to you its Earth's time that is slowing down. From your frame of reference, there's no distinction between you moving one way and the Earth moving the other way.
All of these reference frames are correct.

Then comes the problem:
 
FTL travel, alone, does not violate causality; IE you could fly to alpha centauri with your hyperdrive and fly back, but you wouldn't arrive before you left.
A combination of FTL and STL travel, however, can result in an arrangement of reference frames so where a signal (or, in the case of an ftl ship), arrives before it left.
Imagine you fly away from Earth at relativistic speed. To you, time is passing slower for Earth than for you. After a day, you use your neutrino ftl communications to tell them you forgot to turn the oven off. Since (from your reference frame) time is passing slower for Earth, they receive it in 12 hours. They turn the oven off, then send back a message that they have done so. However, from their frame of reference time is moving slower for you than it is for them, so you receive the reply 6 hours after you left; 18 hours before you send the original message.

There's a more in depth (and probably better informed) explanation to be found here

Edit: Or as it was once explained to me: "The Universe works like this: Special Relativity, Causality, and FTL travel: pick two"

But then why do clocks supposedly lose time when they go to space and not get it back when they return? Isn't time only slowing down for one of these fuckers or is the traveling twin paradox way off?

Before you say "two different FoRs for the space clock", wouldnt it appear to the space dude that the guy on the ground under went the same change between two FoRs?

[Loud Whispers]

What about for those who have done neither?

The basics, as I understand it, are these:

According to special relativity, there is no "one" measurement of space/time that is correct. Instead, there are any number of reference frames.
Most importantly for this discussion, time is not universal in all reference frames; hence the phenomena of time dilation you've probably heard of.
However, time flows normally for each reference frame; if you fly away from Earth at relativistic speeds, to you its Earth's time that is slowing down. From your frame of reference, there's no distinction between you moving one way and the Earth moving the other way.
All of these reference frames are correct.

Then comes the problem:
 
FTL travel, alone, does not violate causality; IE you could fly to alpha centauri with your hyperdrive and fly back, but you wouldn't arrive before you left.
A combination of FTL and STL travel, however, can result in an arrangement of reference frames so where a signal (or, in the case of an ftl ship), arrives before it left.
Imagine you fly away from Earth at relativistic speed. To you, time is passing slower for Earth than for you. After a day, you use your neutrino ftl communications to tell them you forgot to turn the oven off. Since (from your reference frame) time is passing slower for Earth, they receive it in 12 hours. They turn the oven off, then send back a message that they have done so. However, from their frame of reference time is moving slower for you than it is for them, so you receive the reply 6 hours after you left; 18 hours before you send the original message.

There's a more in depth (and probably better informed) explanation to be found here

Edit: Or as it was once explained to me: "The Universe works like this: Special Relativity, Causality, and FTL travel: pick two"

But then why do clocks supposedly lose time when they go to space and not get it back when they return? Isn't time only slowing down for one of these fuckers or is the traveling twin paradox way off?

TIME IS RELATIVE NEUTRINOS.

What can seem like 5 minutes to you, can seem like 5 minutes to the internet.

IN COMPUTER YEARS.

[Osmosis Jones]

There's no such thing as vacuum energy, all we know is, vacuum is the fabric of space, with an absence of matter.

There are quite a few cosmologists who would like a word with you

Also a little experiment called the Casimir effect.

Can't you set up a vacuum energy gradient with the Casimir effect, though?

Neenja. Heh, I missed it at first, but that thought cropped up when I was digging up the above link. I may have to eat my words...

That said, the problem with the Casimir effect is you have to set it up, and I think that whatever you do would cost more energy than you can get out of it.

[Loud Whispers]

There's no such thing as vacuum energy, all we know is, vacuum is the fabric of space, with an absence of matter.

There are quite a few cosmologists who would like a word with you

Also a little experiment called the Casimir effect.

Can't you set up a vacuum energy gradient with the Casimir effect, though?

Neenja. Heh, I missed it at first, but that thought cropped up when I was digging up the above link. I may have to eat my words...

That said, the problem with the Casimir effect is you have to set it up, and I think that whatever you do would cost more energy than you can get out of it.

WELL THEY CAN SHOVE THEIR CAKES AND LIES SOMEWHERE ELSE!
WHERE IS MY (X) BUTTON?

*Looks up Casimir effect*

Dammit life.

[Bauglir]

thobal

Time slows down for both, but only from the other's perspective. The space traveller who travels in a loop at relativistic speed, returning to Earth at the end, may have seen time on Earth pass half as quickly. Earth saw time for the space traveller pass half as quickly. They're both right, and my head is now going to explode. At least if I recall how these shenanigans work, anyway.

[Osmosis Jones]

But then why do clocks supposedly lose time when they go to space and not get it back when they return? Isn't time only slowing down for one of these fuckers or is the traveling twin paradox way off?

Before you say "two different FoRs for the space clock", wouldnt it appear to the space dude that the guy on the ground under went the same change between two FoRs?

Nope, because only the space dude underwent acceleration. That's why it's not a true paradox; the twins experienced different space (acceleration) so they experienced different time. If each twin blasted away from Earth in a rocket, turned around after the same time, and came back, then they'd still be the same age though.

[Loud Whispers]

But then why do clocks supposedly lose time when they go to space and not get it back when they return? Isn't time only slowing down for one of these fuckers or is the traveling twin paradox way off?

Before you say "two different FoRs for the space clock", wouldnt it appear to the space dude that the guy on the ground under went the same change between two FoRs?

Nope, because only the space dude underwent acceleration. That's why it's not a true paradox; the twins experienced different space (acceleration) so they experienced different time. If each twin blasted away from Earth in a rocket, turned around after the same time, and came back, then they'd still be the same age though.

Just suffering different effects of time.
+1

[Bremen]

What about for those who have done neither?

The basics, as I understand it, are these:

According to special relativity, there is no "one" measurement of space/time that is correct. Instead, there are any number of reference frames.
Most importantly for this discussion, time is not universal in all reference frames; hence the phenomena of time dilation you've probably heard of.
However, time flows normally for each reference frame; if you fly away from Earth at relativistic speeds, to you its Earth's time that is slowing down. From your frame of reference, there's no distinction between you moving one way and the Earth moving the other way.
All of these reference frames are correct.

Then comes the problem:
 
FTL travel, alone, does not violate causality; IE you could fly to alpha centauri with your hyperdrive and fly back, but you wouldn't arrive before you left.
A combination of FTL and STL travel, however, can result in an arrangement of reference frames so where a signal (or, in the case of an ftl ship), arrives before it left.
Imagine you fly away from Earth at relativistic speed. To you, time is passing slower for Earth than for you. After a day, you use your neutrino ftl communications to tell them you forgot to turn the oven off. Since (from your reference frame) time is passing slower for Earth, they receive it in 12 hours. They turn the oven off, then send back a message that they have done so. However, from their frame of reference time is moving slower for you than it is for them, so you receive the reply 6 hours after you left; 18 hours before you send the original message.

There's a more in depth (and probably better informed) explanation to be found here

Edit: Or as it was once explained to me: "The Universe works like this: Special Relativity, Causality, and FTL travel: pick two"

But then why do clocks supposedly lose time when they go to space and not get it back when they return? Isn't time only slowing down for one of these fuckers or is the traveling twin paradox way off?

Before you say "two different FoRs for the space clock", wouldnt it appear to the space dude that the guy on the ground under went the same change between two FoRs?

The best explanation for this is "Special Relativity makes no sense, but unfortunately there's a lot of evidence that it's still correct." But yeah, only one underwent acceleration.

[Bauglir]

But then why do clocks supposedly lose time when they go to space and not get it back when they return? Isn't time only slowing down for one of these fuckers or is the traveling twin paradox way off?

Before you say "two different FoRs for the space clock", wouldnt it appear to the space dude that the guy on the ground under went the same change between two FoRs?

Nope, because only the space dude underwent acceleration. That's why it's not a true paradox; the twins experienced different space (acceleration) so they experienced different time. If each twin blasted away from Earth in a rocket, turned around after the same time, and came back, then they'd still be the same age though.

That makes more sense than what I said. Listen to this person, there is wisdom there.

[Loud Whispers]

But then why do clocks supposedly lose time when they go to space and not get it back when they return? Isn't time only slowing down for one of these fuckers or is the traveling twin paradox way off?

Before you say "two different FoRs for the space clock", wouldnt it appear to the space dude that the guy on the ground under went the same change between two FoRs?

Nope, because only the space dude underwent acceleration. That's why it's not a true paradox; the twins experienced different space (acceleration) so they experienced different time. If each twin blasted away from Earth in a rocket, turned around after the same time, and came back, then they'd still be the same age though.

That makes more sense than what I said. Listen to this person, there is wisdom there.

ALL HAIL THE MIGHTY STEVEAPEDIA