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'Einstein Probe' Delayed
isorox writes "The BBC is reporting that a NASA satellite designed to test frame dragging, predicted by the theory of relativity, has been delayed for 24 hours because mission control couldn't verify the correct software had been loaded. The probe was proposed 35 years ago, but has never had the funding until now. The question remains is what happens if Frame Dragging isn't observed - will the experiment be wrong (in other words there's no point to it), or will we get faster-than-light ships for Christmas?"
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The question remains is what happens if Frame Dragging isn't observed - will the experiment be wrong (in other words there's no point to it),
Then you have a Type II error, methinks. It's not that you are wrong outright (like a Type I error. You've just missed the chance to reject the null hypothesis correctly was munged. Refine. Try again.
Comparing it to Windows will be a moot point, since El Dorado is going to have a 40% larger code base than XP.
Except that the general theory of relativity was created because newtonian gravity violated the speed of light. If this test showed that frame dragging did not exist, we would be have to figure out a new way of making those two consistant, and (on the surface at least) one (unlikely) possibility would be that some things can travel faster than light.
I've read that frame dragging had already been reported in astronomical observations, and that this is expected to be an important but unsurprising laboratory confirmation of the phenomenon.
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"...test frame dragging, predicted by the theory of relativity... will we get faster-than-light ships for Christmas?"
What does frame dragging have to do with faster-than-light?? The wikipedia link mentions nothing about how frame dragging has to do with faster-then-light, so I searched google and found this article on msn:
"Spinning black holes may pull in gaseous matter from their sister stars as a rapidly rotating "accretion disk," analogous to water circling down a bathtub drain.
The American scientists built on their previous research into the mass and spin of black holes to look for signs of space-time distortion, or frame-dragging.
In Einsteinian physics, the space-time continuum is often compared to a sheet of rubber. Mass creates a gravitational "dimple" in that space-time sheet. But a rotating object -- like a spinning black hole -- adds an extra twist to the dimple. Matter caught in that twist would appear to wobble in orbit around the object, like a toy top wobbling on its axis.
Cui explained that travelers passing close to a black hole would feel as if "nothing happened." But a distant observer would see the travelers being dragged around the black hole."
my karma will be here long after I'm gone
The question remains is what happens if Frame Dragging isn't observed.
Then they'd better figure out if their experiment was badly designed, because frame dragging has already been observed by other research platforms.
NASA's Rossi X-Ray Timing Explorer observed frame dragging in a distant system consisting of a binary pair of black holes. This was back in 1997.
Analysis of the motion of two earth-orbiting satellites, LAGEOS I and LAGEOS II, also reveals frame dragging going on. This was also over 4 years ago, and it's the result that this Einstein probe is supposed to refine.
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No matter, energy, or information is propagated faster than light in quantum entanglement.
Einstein's theory itself doesn't forbid something from going faster than light. (However, there are problems with FTL objects and causality, such as observers for which effects take place before causes, and tachyons also destablize the vacuum in quantum field theory.) It does forbid objects from crossing the c barrier (which would require infinite energy).
In a theory with Lorentz symmetry (i.e., relativity), there is only one invariant speed: the speed of light. There can't be another speed (faster or slower than c) that is invariant in all inertial frames.
In relativity, massless objects can travel at only one speed (c), neither faster nor slower.
Disclaimer - I worked on the Gravity Probe B (GPB) team back in 1994-1995 while I was an undergraduate at Stanford. Due to personal interest, I watched the launch attempt on NASA TV.
While technically correct, the post's claim that the lauch was delayed "because mission control couldn't verify the correct software had been loaded" doesn't convey the whole picture of what happened.
Well prior to T minus 4 minutes, three weather balloons had reported excessive (out of limits) high altitude wind shear. This wind shear would have caused the launch to be delayed for 24 hours.
However, shortly after T minus 4 minutes, a fourth weather balloon reported that windshear had dropped to within acceptable limits. At this time, the flight profile of the delta II rocket needed to be updated to successfully guide the rocket through the high altitude wind shear and in to GPB's desired orbit.
The launch window for GPB is very narrow - about one second. This is because GPB needs to be in a polar orbit in the plane of a particular guide star.
A launch director from Boeing (Boeing made the delta II rocket) could not confirm that the flight profile had been successfully updated. So, with the clock counting down, he made the decision to "hold" the launch. Upon review, all the launch directors agreed that this was the correct decision.
So, you have a situation where, under time pressure, about 300 seconds before launch, due to changing launch conditions and unverifyable equipment status, a conservative and correct decision was made to delay the lanch 24 hours - until the next one second long launch window.
The other thing to consider is that the closer you get to launch, the more costly and complicated it is to abort the launch. So even though confirmation of a successful profile upload may have come later, if it hadn't, the costs of scrubbing the launch would be higher.
While it may be fun to bash NASA, just remember that it really is rocket science, at least in this case.
He still cannot accelerate to or past the speed of light. If he were enclosed in a box traveling at a constant velocity => lightspeed, then yes everything would appear normal to him, and it's only the stationary observer who would notice anything odd. However, assume that same box is ACCELERATING to lightspeed, and suddenly the man in the box is exposed to all of the effects that entails. Namely, mass going to infinity, and energy required to continue acceleration going to infinity.
.... But the more massive an object is, the harder it is to increase its speed. .... Since a the mass of a muon increases without limit as its speed approaches that of light, it would require a push with an infinite amount of energy to reach or to cross the light barrier. This, of course, is impossible and hence absolutely nothing can travel faster than the speed of light."
Let me dig up a reference...
The Elegant Universe, by Brian Greene, PhD (from Oxford)
Page 52
"You may have wondered, for instance, why6 we can't take some object, a muon say, that an accelerator has boosted up to 667 million miles per hour -- 99.5 percent of light speed -- and "push it a bit harder," getting it to 99.9 percent of light speed, and then "really push it harder" impelling it to cross the light speed barrier. Einstein's formula explains why such efforts will never succeed. The faster something moves the more energy it has and from Einstein's formula we see that the more energy something has the more massive it becomes. Muons traveling at 99.9 percent of light speed, for example, weigh a lot more than their stationary cousins. In fact, they are about 22 times as heavy -- literally.
I was actually just talking to my advisor about this (astronomy chair) and the basic idea is this: the scientific communtiy has been killing this project constantly (he several times graphically depicted shooting something on the ground) just to have someone in congress decide to bring it back. It's the most illconceived experiment - they are trying to measure not only what has been completely PROVEN but also in the most inane manner. Just about everything else that affects the gyroscopes are larger effects, what they are trying to detect is so small. When this was first thought up, it was probably kind of novel, but we're beyond that (can you say strings) now and its just one messey experiment (would you want to do the math for that?).
So why not work on something useful like alternate propulsion systems or batteries that keep my mp3's coming for more than 10 hours....
When Kepler figured out the planetary orbits, he envisioned invisible brooms sweeping the planets towards the sun. When I read "gravity is just curved spacetime" I think of Kepler's brooms as they both seem to say about as much.
:-)
Think more like a bowling ball on a trampoline. The bowling ball will "warp" the trampoline, and objects placed on the trampoline will fall toward it.
As for planetary motion, I'm sure you've seen those funnels that you put coins in. The coin spins round and round. Friction eventually slows it down enough to fall toward the center. If your coin was in a vacuum and had sufficient velocity, it could keep going around the center forever. (e.g. The Earth keeps "missing" the Sun)
Just how does mass warp space? How does space know the mass is around?
We don't know the former yet. Space knows mass is around, because at a quantum level matter and energy are inbalances in the vacuum. "Empty" space is really a bunch of wild waves called "quantum foam" that all cancel each other out.
What particle is gravity's carrier?
Gravitons are only theoretical. At this point it looks like they don't exist. In other words, gravity waves are perpetrated in a vacuum instead of by a particle like the strong force's gluon.
If there is a gravity particle, how come planets don't speed up as they plow into them orbiting the sun?
If a planet heads toward the Sun (not a good thing) it *will* speed up. The trick is that a stable orbit implies having *just enough* speed to keep missing the object.
And how come it gets to escape black holes but no other particles can come out and play?
Because there's no particle. It's the nature of space-time.
We can describe gravity's effects but we can't say how it does the trick.
General Relativity says gravity == acceleration. Therefore, the presence of matter and energy "slopes" space-time in such a way as to accelerate all other particles in the Universe.
Javascript + Nintendo DSi = DSiCade
This aired last Friday on public radio:
Talk Of The Nation Science Friday
Seek to 27:30 for the start of the audio program on Frame Dragging.
To blog is sublime
Everyone should be clear: the "software" that they couldn't verify was the flight plan for the launch vehicle, not the software on the satelite.
Variable high-altitude winds just prior to launch required them to update the flight control parameters, but they couldn't verify that the update was successful in the final 4 minutes before launch. Better safe than sorry, so they scrubbed it 'till tomorrow.
They can't afford to launch a satellite only to discover there was a bug in the software and have it be worthless
If you look at Gravity Probe B's Site you will find that the software that they are referring to has nothing to do with the probe itself but rather there was insufficient time to confirm that the Delta II rocket had the correct wind profile loaded for the data from the final weather balloon.
They wanted to make sure that the rocket had the data from the last weather balloon and there wasn't enough time to make sure.
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