Was Einstein Wrong about Space Travel?

NASA ^ | 03/22/06

[KevinDavis]

March 22, 2006: Consider a pair of brothers, identical twins. One gets a job as an astronaut and rockets into deep space. The other stays on Earth. When the traveling twin returns home, he discovers he's younger than his brother.

This is Einstein's Twin Paradox, and although it sounds strange, it is absolutely true. The theory of relativity tells us that the faster you travel through space, the slower you travel through time. Rocketing to Alpha Centauri—warp 9, please—is a good way to stay young.

[Lx]

OK, so what happend to the bad boy (and ugly) Trans warp speed starship in the Search for Spock where Scotty took parts out of it so they couldn't catch the Enterprise, did they drop that idea for the series?

C'mon, I gotta do something to kill time waiting for South Park.

[Number57]

Not yet... but I found this one:

[tickmeister]

That exact question has bothered me for several years. I've never heard an explanation. Of course, I've never looked very hard. Maybe we should take up a collection and hire somebody to explain it to us.

[daku]

"Why don't they always travel warp 10?"

I always run my ship at warp 11 ... it's one more

[freedumb2003]

LOL

[warpsmith]

the difference is that only one of the twins 'feels' the acceleration.

yeah, I know that doesn't help a lot...

[freedumb2003]

I always run my ship at warp 11 ... it's one more

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[RightWhale]

Evidently if they cranked it to warp 10 they would be everywhere at once, so they would do something short of that.

What they did was note how far to their next mission location and adjust the warp drive so they would arrive in slightly less than a week--just in time for the next show.

[tanknetter]

Warp 10 is transwarp speed, something not attainable by Star Trek Federation ships within the series.

Actually, Voyager did it. Once. IIRC Janeway and Paris got caught up in a DNA/reverse-evolution thing as a result ... which turned them into lizards. They mated, and had lizard offspring. Which were left behind when the reverse-evolution was reversed.

(and I am SO completely embarassed that I know this)

[tanknetter]

OK, so what happend to the bad boy (and ugly) Trans warp speed starship in the Search for Spock where Scotty took parts out of it so they couldn't catch the Enterprise, did they drop that idea for the series?

Yup ... said it was "unworkable", although the Excelsior-class starships were redesigned for conventional warp engines.

Transwarp showed up again as a method of travel used by the Borg. In that case Transwarp was described as more of a conduit - a point-to-point wormhole effect.

[fishtank]

Do you know where there is a table of warp vs. the speed of light?

I tried to find one once.

[RHINO369]

"(and I am SO completely embarassed that I know this)"

I could tell you, that you shouldn't be, but you should.

[GregoryFul]

My question has been, if there were triplets, one gots off in a spaceship at 1/2 the speed of light north, one goes 1/2 the speed of light south, and the third stays on earth. When the traveling brothers (sisters) return to earth, are they the same age?

[mikrofon]

There was one forgettable episode of ST:Voyager (weren't they all?) where they equipped one of their shuttles(!) to go over Warp 10 -- the pilot ended up dying as a result, then resurrected, devolved into some sort of lizard, kidnapped Capt. Janeway to some swamp planet, turned her into a fellow lizard, and mated with her producing a litter of 'gators before the Doctor miraculously "reversed the process"...

[mikrofon]

(and I am SO completely embarassed that I know this)

Dittos ;)

[Number57]

The Twin Paradox of Einstein is an interesting thought experiment involving two twins (who are nearly exactly the same age), one of whom sets out on a journey into space and back. Because of the time dilation effect of relativity, the twin who left experiences a slowing down of time and will actually be much younger than the twin that stayed behind. The reason that this is considered a paradox is that Special Relativity seems to imply that either one can be considered at rest, with the other moving. It does, and it doesn't.

The confusion arises not because there are two equally valid inertial rest frames, but (here's the tricky part) because there are three. A lot of explanations of the twin paradox have claimed that it is necessary to include a treatment of accelerations, or involve General Relativity. Not so.

The three inertial frames are 1) at-home twin 2) the going-away twin and 3) the coming-back twin. It doesn't make any difference that the last two are physically the same twin--they still define different inertial frames.

OK, let's see: Ann stays at home and Bob rockets away at 3/5 light speed. Time dilation is 80%. Bob lets 4 years pass. Bob returns at 3/5 light speed, again taking 4 years. Ann thinks 10 years have passed, and Ann and Bob agree that Bob is two years younger.

Important question: what is the relative speed of the two Bob frames? On first glance, it would appear that one is going 3/5c in one direction and 3/5c in the other direction, so that the difference between the two frames is 6/5c! Faster than light? No, special relativity does not add speeds this way. The actual difference is only 15/17c, fast but not faster than light. Why is this important? We'll see.

Now, since special relativity lets us use either rest frame, we assume Bob is the at-home twin. Ann speeds away at 3/5c. No problem so far. But after 4 years of waiting, Bob must change his inertial frame. If we allow Ann to return, we've only restated the problem with the names switched. In the first version, Ann stayed in an inertial frame, and she must stay in an inertial frame in this version. Bob zooms off after Ann at 15/17 light speed (now we know why it was important), and of course catches up. It takes him 4 years, and he has seen 8 years since Ann left. Ann has aged 10 years. Same result. No paradox.



/hadda do it

[dangus]

The basic problem with Warp 10 is its asymptotic. Any time you cut your distance to warp 10 in half, you double your mass, and hence need twice as much fuel. Therefore, as you approach warp speed, your mass approaches infinity.

Of course, it doesn't seem to YOU like your mass is increasing. To YOU, the Newtonian physics seem consistent; Your perspective is increasingly warped. Again, every time you half your distance to warp 10, your experience of time is cut in half. You don't SENSE that to achieve ever-decreasing rates of acceleration, ever-increasing amounts of time pass for those you are zooming past. YOU sense you are continuing your acceleration at a linear rate (if I've got that right), but time is flying by at exponentially greater speeds, until, before you know it, the universe has already collapsed apon itself.

Of course, you will experience this as merely having travelled beyond the reaches of the universe.

[dangus]

Well, he didn't exactly stay home. It's just that Priceline books travels that are at speeds insignificant to the effects of relativity.

[Psycho_Bunny]

Any time I hear "You can't travel faster than light" I hear, "You can't travel faster than sound".

[Lunatic Fringe]

Hey that reminds me... HAPPY BIRTHDAY, Capt. Kirk!