Down Rodeo
Cap'n Moth of the Firehouse
2007 Oct 19 • 5486
57,583 ₧
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An inertial frame is defined as one in which Newton's second law holds, so provided there is no force acting on the stick, it's an inertial frame.
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2010 Sep 30 at 21:28 UTC
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Rockbomb
Dog fucker (but in a good way now)
2009 Nov 14 • 2045
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I find this very interesting, yet I have no clue whats going on? Why is the stick changing sizes? 
I guess I should probably go look up what special relativity is, but I don't feel like it, so I'll wait for you to explain 
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2010 Sep 30 at 21:36 UTC
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Down Rodeo
Cap'n Moth of the Firehouse
2007 Oct 19 • 5486
57,583 ₧
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Special relativity is the theory that describes how bodies move at velocities close to light. It's weird, but one of its (experimentally verified) predictions is that lengths are contracted. Another is that clocks moving relative to you appear to run slowly, and there's a quick argument I can run through if you like :)
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2010 Sep 30 at 22:26 UTC
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e=mc^shutup, where shutup=2.
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2010 Sep 30 at 22:27 UTC
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Down Rodeo
Cap'n Moth of the Firehouse
2007 Oct 19 • 5486
57,583 ₧
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That is also part of Special Relativity, the equivalence of matter and energy. The full equation involves momentum so it can describe massless particles too.
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2010 Sep 30 at 22:32 UTC
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Rockbomb
Dog fucker (but in a good way now)
2009 Nov 14 • 2045
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Down Rodeo said: Special relativity is the theory that describes how bodies move at velocities close to light. It's weird, but one of its (experimentally verified) predictions is that lengths are contracted. Another is that clocks moving relative to you appear to run slowly, and there's a quick argument I can run through if you like :)
Is it saying that the objects ACTUALLY are contracted, or just that they appear contracted?
Also what experiments have they done to verify this? A stick moving at the speed of light would be pretty fuckin dangerous 
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2010 Sep 30 at 23:05 UTC
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Down Rodeo
Cap'n Moth of the Firehouse
2007 Oct 19 • 5486
57,583 ₧
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Let's go with "appear". Because as has been outlined from the stick's frame it is normal size. The thing to take away from this discussion is that things you might normally take as constant (lengths, speeds, that sort of thing) are not in fact constant. You should in fact rely on the speed of light in vacua to be constant, no matter your inertial frame.
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2010 Sep 30 at 23:35 UTC
— Ed. 2010 Sep 30 at 23:35 UTC
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Down Rodeo said: An inertial frame is defined as one in which Newton's second law holds, so provided there is no force acting on the stick, it's an inertial frame.
I misunderstood the question. I thought the stick was flying back at the spectator after it entered the barn, not just passing through it, so I assumed the stick changed direction without accelerating.
SRAW said: hey a rare cameo by adhesive
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2010 Oct 1 at 01:30 UTC
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aaronjer
*****'n Admin
2005 Mar 21 • 5105
1,227 ₧
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That's what it sounded like to me too.
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2010 Oct 1 at 04:31 UTC
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Rockbomb said:
Is it saying that the objects ACTUALLY are contracted, or just that they appear contracted?
Also what experiments have they done to verify this? A stick moving at the speed of light would be pretty fuckin dangerous
Try the atmospheric muon experiment I guess. Also particle accelerators are designed very carefully to accommodate for length contraction. And they work, too, so that's pretty good evidence.
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2010 Oct 1 at 07:11 UTC
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SRAW
Rocket Man
2007 Nov 6 • 2525
601 ₧
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Question solved. New one:
What happens if you reach the end of teh univarse?
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2010 Oct 1 at 08:14 UTC
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code int main(void){ for(i=0;i<EDGE_OF_UNIVERSE;i++) if(i==EDGE_OF_UNIVERSE-1) i=0; return 0; } |
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2010 Oct 1 at 16:39 UTC
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How about this?
code int main(void){ for(i=0;i<EDGE_OF_UNIVERSE;i++) EDGE_OF_UNIVERSE *= 2; return 0; } |
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2010 Oct 1 at 19:52 UTC
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Down Rodeo
Cap'n Moth of the Firehouse
2007 Oct 19 • 5486
57,583 ₧
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It's quite easy to construct a universe which is finite but boundless (i.e. has no edge).
And yes, Superjer is correct: in essence, muons should not reach the surface of the Earth because they have a half-life of 2.2 microseconds, even at the speeds they travel at that's too short a time to reach the surface without decaying.
On the other hand we detect lots and lots of muons. So basically they're travelling quickly, their "internal clock" runs slowly and they reach the Earth. You can also measure the differences in muon counts at the bottom and top of a hill, for instance.
adhesive said: Down Rodeo said: An inertial frame is defined as one in which Newton's second law holds, so provided there is no force acting on the stick, it's an inertial frame.
I misunderstood the question. I thought the stick was flying back at the spectator after it entered the barn, not just passing through it, so I assumed the stick changed direction without accelerating. Ah, my bad. It's best to think of the spectator standing at one side of the barn, looking through a window or something. Again, this is all thought, since I know SRAW will complain. I might edit the original post to make it slightly clearer.
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2010 Oct 1 at 21:24 UTC
— Ed. 2010 Oct 1 at 21:25 UTC
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SRAW
Rocket Man
2007 Nov 6 • 2525
601 ₧
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When did I complain... 
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2010 Oct 2 at 00:10 UTC
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Down Rodeo said: It's quite easy to construct a universe which is finite but boundless (i.e. has no edge).
Maybe for you. I've been trying to get mine constructed for weeks and I can't get past a massless singularity. 
Down Rodeo said: Again, this is all thought, since I know SRAW will complain. I might edit the original post to make it slightly clearer.
SRAW said: When did I complain... I count this as the complaint.
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2010 Oct 2 at 02:37 UTC
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Down Rodeo
Cap'n Moth of the Firehouse
2007 Oct 19 • 5486
57,583 ₧
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SRAW said: This stuff isn't even proven yet, that's why we call them theories, so no point to debate on something that isn't true  Sounds like a complaint to me
Supes: have you tried duct tape?
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2010 Oct 2 at 11:37 UTC
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Down Rodeo
Cap'n Moth of the Firehouse
2007 Oct 19 • 5486
57,583 ₧
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I was thinking about this in lectures this morning, so I will put the question to you guys: the Twins Paradox. As has been said, Special Relativity predicts that time intervals are lengthened for objects moving relative to an observer. So let's say one of a pair of twins jumps in a rocketship and flies away in one direction for 5 years at close to the speed of light. He then turns around and heads back to Earth for another five years, arrives, and there is rejoicing. But according to SR the twin should actually be older from the relatively stationary Earth! Is this right? Is there really this paradox?
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2010 Oct 4 at 14:01 UTC
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Well from the viewpoint of the travelling twin, it's the Earth that's moving at close to light speed for 10 years, so it's the Earth that's getting older faster. I guess that the two agings kind of cancel each other out. 
...and that's the bottom line because Mate de Vita said so.
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2010 Oct 4 at 20:07 UTC
— Ed. 2010 Oct 4 at 20:07 UTC
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Down Rodeo
Cap'n Moth of the Firehouse
2007 Oct 19 • 5486
57,583 ₧
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Mate de Vita said: Well from the viewpoint of the travelling twin, it's the Earth that's moving at close to light speed for 10 years, so it's the Earth that's getting older faster. I guess that the two agings kind of cancel each other out. Actually, you have highlighted the (apparent) paradox - both viewpoints predict that the other twin will have aged, so who's right? They don't cancel out.
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2010 Oct 4 at 21:06 UTC
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NatureJay
SJA: Commander of Ruthless Abuse
2005 Mar 23 • 1871
574 ₧
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superjer said: Down Rodeo said: It's quite easy to construct a universe which is finite but boundless (i.e. has no edge).
Maybe for you. I've been trying to get mine constructed for weeks and I can't get past a massless singularity. That's what you get for shopping at IKEA.
100% natural, no antibiotics, and bloodgrass-fed
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2010 Oct 5 at 01:44 UTC
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The spaceship must decelerate, stop, and accelerate back towards it's initial position. Since the spaceship's reference frame is non-inertial the Principle of Relativity does not apply so we cannot calculate time dilation through the time dilation formula.
The Earth clocks do indeed run slow as the spaceship moves at constant velocity, however while the spaceship decelerates and turns around the Earth clocks run fast. Fast enough that the spaceship twin will be younger upon return.
SRAW said: hey a rare cameo by adhesive
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2010 Oct 5 at 03:06 UTC
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Down Rodeo
Cap'n Moth of the Firehouse
2007 Oct 19 • 5486
57,583 ₧
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I was trying to reply to this earlier but the forums ate my reply. Probably a good thing I didn't anyway as I now think I might have been wrong but in my defence I was doing lots of Java which is never good for you.
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2010 Oct 5 at 19:50 UTC
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Rockbomb
Dog fucker (but in a good way now)
2009 Nov 14 • 2045
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Down Rodeo said: I was trying to reply to this earlier but the forums ate my reply. Probably a good thing I didn't anyway as I now think I might have been wrong but in my defence I was doing lots of Java which is never good for you.
Yeah, you should switch to cappuccino...
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2010 Oct 5 at 22:54 UTC
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buq25
2008 Jul 5 • 583
295 ₧
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DIS MIHT BEH INTARSTIN:
Sick vid
Sick vid
Today's post brought to you by the letter: "heck".
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2010 Oct 11 at 19:50 UTC
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