Free Republic
Browse · Search
News/Activism
Topics · Post Article

Skip to comments.

Was Einstein Wrong about Space Travel?
NASA ^ | 03/22/06

Posted on 03/22/2006 5:34:03 PM PST by 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.

(Excerpt) Read more at science.nasa.gov ...


TOPICS: Miscellaneous; News/Current Events
KEYWORDS: 1point21gigawatts; einstein; space; spacetimecontinuum; spacetravel
Navigation: use the links below to view more comments.
first previous 1-20 ... 81-100101-120121-140141-142 next last
To: dr_lew
Some physicist (wish I could remember who) said that a better name for our particle accelerators would be particle preponderators, because most of the energy they impart to the particles doesn't do much acceleratin', because the particles get very close to C very soon; after that, it's almost all preponderatin'.
101 posted on 03/22/2006 9:06:06 PM PST by Erasmus (Eat beef. Someone has to control the cow population!)
[ Post Reply | Private Reply | To 95 | View Replies]

To: Lunatic Fringe
Because warp 10, in the Star Trek universe of physics, is the speed at which you occupy multiple points in space.

I seem to recall that they were traveling faster than Warp 10 in the very last episode of TNG. That was the one where Picard was simultaneously experiencing three different time periods, and in the most futuristic time (where everyone was old and gray) the new, improved Enterprise was traveling at Warp 13 under Admiral Riker's command, I think. They were trying to figure out what created the huge anti-time disturbance that wiped out all of mankind, and eventually realized it started in the future and moved backwards through time, growing larger as it went earlier and earlier into history.

Uh, or something like that. Not that I ever watched that show or anything...

102 posted on 03/22/2006 9:06:18 PM PST by Ryan Spock (The number one rule of the Kama Sutra is that you both be on the same page)
[ Post Reply | Private Reply | To 12 | View Replies]

To: skateman
Is faster than light travel possible?

The only way to fly!

103 posted on 03/22/2006 9:10:09 PM PST by Erasmus (Eat beef. Someone has to control the cow population!)
[ Post Reply | Private Reply | To 93 | View Replies]

To: Ryan Spock

Actually a double episode, #177 and #178, broadcast originally during May of 1994 and entitled "All Good Things..." Picard eventually discovers, as he travels back and forth through time, that paradoxically HE has created the temporal anomaly which threatens to annihilate all life in the universe.


104 posted on 03/22/2006 9:17:06 PM PST by Jack Hammer
[ Post Reply | Private Reply | To 102 | View Replies]

To: skateman
What speed velocity would this kind of travel take?

The best you could hope to achieve would be some "large fraction" of the speed of light, so that your trip time would be comparable to the light travel time, so we're talking generation ships, or suspended animation here.

I saw a paper once years ago ( like forty years ago ) that outlined the payload for an acceleration and deceleration to and from .9c . It was ridiculous. Assuming conversion of fuel mass into pure light-speed propulsion, the payload was something like 1/100,000 or whatever. Very discouraging!

Interstellar ramjets? At "gamma = 2" or .86c, it costs as much kinetic energy to scoop up a particle as can be gained by ejecting its rest energy as photons, the theoretically best propulsion efficiency.

... Corrections cheerfully acknowledged !

105 posted on 03/22/2006 9:18:18 PM PST by dr_lew
[ Post Reply | Private Reply | To 98 | View Replies]

To: Ryan Spock

Actually a double episode, #177 and #178, broadcast originally during May of 1994, once again featuring the relationship between the Captain of the Enterprise and the entity known as Q, and entitled "All Good Things..." Picard eventually discovers, as he travels back and forth through time, that, paradoxically, HE has created the temporal anomaly which threatens to annihilate all life in the universe.


106 posted on 03/22/2006 9:19:14 PM PST by Jack Hammer
[ Post Reply | Private Reply | To 102 | View Replies]

To: Jack Hammer

Sorry for the double - er, triple, now - post. For a moment there, my computer seems to have entered the aforementioned temporal anomaly. Or maybe it just went nuts. Picard, indeed, expressed the same concern about himself.


107 posted on 03/22/2006 9:21:50 PM PST by Jack Hammer
[ Post Reply | Private Reply | To 106 | View Replies]

To: KevinDavis

I just want my flying car!!!


108 posted on 03/22/2006 9:24:16 PM PST by right way right
[ Post Reply | Private Reply | To 1 | View Replies]

To: Lunatic Fringe
Because warp 10, in the Star Trek universe of physics, is the speed at which you occupy multiple points in space.

Mine's got eleven.

109 posted on 03/22/2006 9:35:55 PM PST by MistrX
[ Post Reply | Private Reply | To 12 | View Replies]

To: Erasmus
...because the particles get very close to C very soon; after that, it's almost all preponderatin'.

In my graduate education, the idea of mass dilation was deprecated. It is after all predicated on the imperative to preserve F = ma. It was pointed out that mass became a directional quantity, since the particle's resistance to perpendicular acceleration was not increased at all, so it was better to identify the concept of mass with the "rest mass", and simply adopt the relativistic momentum, presevering the Newtonian F = dP/dt.

I arrived at the idea that "hitting power" was the measure of speed to be adopted, instead of travel time, much as in ballistics. A bullet going at 0.99c is going to dump 7.1 times its rest energy into a target, compared with 2.3 for a .9c bullet, so it has about 3 times the kinetic energy even if it's only going 10% faster by elapsed time.

It's interesting. I've seen both tennis and hockey commentators speak of "heavy" shots, as though there were some mystical ability to impart momentum to a ball or puck, independently of making it go faster. Pffffffthathinatin'

110 posted on 03/22/2006 9:41:18 PM PST by dr_lew
[ Post Reply | Private Reply | To 101 | View Replies]

To: mathurine

I'm not going to, uh, with a ten foot, uh...


111 posted on 03/22/2006 9:56:07 PM PST by SunkenCiv (Yes indeed, Civ updated his profile and links pages again, on Monday, March 6, 2006.)
[ Post Reply | Private Reply | To 86 | View Replies]

To: Erasmus
I believe the asymmetry lies in the acceleration.

This is logically correct, but possibly misleading. The twin paradox pertains even when the "clock hypothesis", that there are no physical effects on a clock due to acceleration, is adopted.

The simplest model I know of for the twin paradox is to assume an instantaneous transfer of the twin from an outbound to an inbound spaceship, at the same relative speed. In this case the outbound and inbound legs are both "time dilated" by the same amount and the twin arrives younger by a factor of 1/gamma.

Alternatively, one can simply accept, according to the clock hypothesis, that the "proper time" experienced by an object is the "integral of d_Tau", measured in any inertial frame. Thus was the twin paradox dispensed with forthwith in one pithy exposition I read once. Note that the twin can travel along any path of a given length at constant speed, arriving back at earth, and experience the same aging deficit. All hail pithiness.

112 posted on 03/22/2006 10:18:09 PM PST by dr_lew
[ Post Reply | Private Reply | To 100 | View Replies]

To: Delta Dawn
I wonder what happens when you microwave a slice of pizza at warp speed?

"You just blew my mind!"


113 posted on 03/22/2006 10:33:40 PM PST by Lunatic Fringe (http://ntxsolutions.com)
[ Post Reply | Private Reply | To 64 | View Replies]

To: Number57

Welcome, where have you been?


114 posted on 03/22/2006 10:36:51 PM PST by duckln
[ Post Reply | Private Reply | To 56 | View Replies]

To: duckln

Lurking... lol. I'm the dumb geek.


115 posted on 03/22/2006 11:19:24 PM PST by Number57
[ Post Reply | Private Reply | To 114 | View Replies]

To: mikrofon

The episodes with Seven of Nine were rather memorable, I thought :-)


116 posted on 03/23/2006 3:19:26 AM PST by alnitak ("That kid's about as sharp as a pound of wet liver" - Foghorn Leghorn)
[ Post Reply | Private Reply | To 54 | View Replies]

To: dangus; fishtank

I thought the cube of the warp number was the light-speed-multiple - Warp 2 is eight times the speed of light, Warp 3 is 27 times, etc.


117 posted on 03/23/2006 5:21:58 AM PST by DuncanWaring (The Lord uses the good ones; the bad ones use the Lord.)
[ Post Reply | Private Reply | To 76 | View Replies]

To: tanknetter; Lx; RightWhale; Dawsonville_Doc

I'm not much of a trekkie, so this could be totally off-base

iirc, in the original series, the warp factors worked like so:

1=C, 2=2C, 3=4C, 4=16C, 5=256C etc... a square progression

and, in the movies and TNG, worked like so:

1=C, 2=2C, 3=8C, 4=64C, 5=4096C etc... a cube progression

like I say, I'm not a Trekkie, so I could be totally wrong on this


118 posted on 03/23/2006 6:29:52 AM PST by King Prout (many complain I am overly literal. this would not be a problem if so many were not under-precise)
[ Post Reply | Private Reply | To 50 | View Replies]

To: King Prout

In the original series Warp was a square progression (btw, that means W1=1C, W2=4C, W3=9C, W4=16C, W5=25C)

In TNG, it's an exponential curve with Warp 10 equaling infinty.

IIRC, YMMV.


119 posted on 03/23/2006 6:41:54 AM PST by Dawsonville_Doc
[ Post Reply | Private Reply | To 118 | View Replies]

To: Dog Gone
"The problem with the Theory of Relativity is that once you understand it, at least conceptually, everything becomes relative.

And then everything you think is common sense turns out to be false, so you either begin drinking heavily or just huddle in a corner and shake.

Or you start watching South Park to make some meaning of life."

I especially enjoyed last night's episode of South Park.

It gave new meaning to my life.

Relatively speaking, of course.

120 posted on 03/23/2006 6:44:15 AM PST by chs68
[ Post Reply | Private Reply | To 11 | View Replies]


Navigation: use the links below to view more comments.
first previous 1-20 ... 81-100101-120121-140141-142 next last

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.

Free Republic
Browse · Search
News/Activism
Topics · Post Article

FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson