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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?"
-- johntracy.com, because everybody else is wrong.
I'm voting for warp drive on this one!
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because mission control couldn't verify the correct software had been loaded.
Man, I must have missed a career as NASA flight controller, because I feel exactly the same way each time XP goes to windowsupdate.microsoft.com...
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
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.
by British scientists!
--- You shall know the truth, and the truth shall make you mad- Neal (not Cowboy) Boortz
Its 2004, I was supposed to have my flying car and a moon base by now. These "scientists" dont have their priorities straight.
WTF was that, "Carl Sagan's Cosmos: Brought to you by the Dick Cheney Foundation?"
Whenever I try to run games at too high resolution on this computer, the frames just start dragging along...
you dumbass .. that's like saying Newton was wasting his time coming up with his theories .. I mean who knew there'd be any practical applications of figuring out the laws of physics?
They had built the pyramids and horse & buggy just fine without Newton.
Frankly, I hope they find that einstein was wrong and that there is a way to easily "bend" what we observe in the curvature of space time.
Imagine a warp bubble rendering the contents essentially massless, thus the input energy for kinetic motion is miniscule enabling fantastic speeds.
However if they are right, that might mean that general relativity rules and we are forced to live by it's law (It's still a theory, will this make it a law?). How unfortunate.
Never let your sense of morals prevent you from doing what's right. --Isaac Asimov
Man, stop smokin the crack:
1) Good result, but result appears to confirm the prediction - this is a successful experiment - a negative result is as valid as a positive one.
1) Good result, and result appears to confirm the prediction - this is a successful experiment
That says the same freaking thing!! Not to mention you started at 1, went to 2, and then did 2 more 1's just trying to get to "four posibilities."
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?
:)
Let me put it this way:
Greetings from next Tuesday!
As a classically trained scientist, I'd be loathe not to point out a misconception here.
Experiments themselves are never 'wrong' experiments are merely poorly designed or interpreted. If they are niether of these then the experiment simply gives you data which you must explain. If it doesnt give you the expected results, it may not be the design that is in error, but instead our understanding of the world.
Data never lies, except when viewed through a human bias.
Surely you mean:
1) Bad result, but result appears to confirm the prediction - this is not a successful experiment
2) Bad result, but result appears to invalidate the prediction - this is not a successful experiment. Possibility of an insufficiently sensitive instrument, or just a badly designed experiment.
3) Good result, but result appears to contradict the prediction - this is a successful experiment - a negative result is as valid as a positive one.
4) Good result, and result appears to confirm the prediction - this is a successful experiment
I am artificially intelligent.
Excuse me, but are you nuts ??
The American space program is one of the safest in the world, thats why they're being so cautious with the shuttle fleet.
The Russian space program on the other hand has been known to take huge saftey/performance/cost trade offs in order to get things off the ground ( no pun intended ). Just because the Russians are launching day and night does NOT imply a higher operational saftey. You are mistaking the effect for the cause, sir.
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.
The aliens invented the horse and buggy?
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
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.
I guess one could accuse certain modern physicists of coming up with "theories that fit reality". But we should remember that Einstein came up with his theories when most of them could not have been possibly proven correct or wrong, so there are at least some theories there, that are not after the fact descriptors of reality but true predictors of the behaviour of the universe.
As far as the usefulness of this, it is also usefull to know how the world around you works. Take nuclear physics -- i am sure people would have characterized the early experiments with radium as pointless, but now the long term future of humanity depends on nuclear energy. The ultimate destruction of humanity also depends on nuclear energy. So whether you are pro or anti humans, nuclear energy is your best bet!!!
In this case its called "foot dragging", not "frame dragging".
Table-ized A.I.
The American space program is one of the safest in the world
Funny, I sort of remember that Soyuz capsules have a better safety record than space shuttles. Hell, they're even used as emergency reentry vehicles on the ISS...
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
The question remains is what happens if Frame Dragging isn't observed
You can listen to John Turneaure, co principle investigator for Gravity Probe B. He was interviewed by Ira Flatow on NPR's Science Friday.
When Ira Flatow asked him what would happen if the probe did not find anything and that Einstein might be wrong, he "hemmed and hawwed" a lot and said that wouldn't be the case - that Einstein was right. He also mentioned that the data would go to a physicist and then be released to the public.
It's not that I'm wearing a tin-foil hat (well maybe), but science is based on conducting experiments in the open and openly sharing data with an unbiased view and procedure, even if it means that Einstein might be wrong.
If they really wanted to do this neat, they would stream the data live to a website, rather than can up the data until they are ready to release it.
There are critics of Einstein that are academically serious and not off their rocker like some zero point/tesla fanatics. There have been critics of Einstein ever since he released his theories. You don't hear much about them as they are all heaped into one group and astrocized.
I am not saying that Einstein was wrong (not in the sense that Newton was wrong either), but that true science is keeping an open mind, rather than cower to the politically favorable theory of the moment.
As an aside, frame dragging is like when you take a single electric mixer and use it in a bowl of pudding. Or when you use an electric stirrer in a can of paint. That is frame dragging.
This happens because gravity is a field (according to Einstein). Newton treated gravity like a force.
Physicists reading may improve upon this anology.
Take the cheese to sickbay, the doctor should see it as soon as possible - B'Elanna Torres, "Learning Curve"
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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
A question for physicists?
:: electricity:magnetism
You know how there is an electric force caused by electric charges and a magnetic force caused by the movement of electric charges. Then when you study maxwell they tell you that the electric and magnetic forces are really two aspects of one force.
Is frame dragging the result of a force that is equivalent to magnetism for gravity. In SAT analogy terms, is:
gravity:frame dragging force
To observe time warping, they will launch a probe into space with balls in vacuum flasks frozen to near absolute zero 400 miles above the earth. They are making it hard. There is really nothing to time warping.
It's just a jump to the left
And then a step to the right
Put your hands on your hips
And bring your knees in tight
And it's the pelvic thrust that really makes you insane
Let's do the time warp again!
Let's do the time warp again!
How ya like dat?
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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Building a ship to go faster than the *speed* of light is (relatively, ha ha) easy. Building a ship to *pass* light is difficult. No matter how fast you chase after that light (even if you cross the universe in seconds!), it will always remain 300,000 km/sec faster than you are! And if you do manage to reach light speed (good luck) you'll be just as frozen in time as photons are. In other words, you'll get to travel the universe, but you'll never know that you did it.
Of couse, the only way we know we're travelling "faster than the speed of light" is that we can measure the time between our point of origin and our point of destination. Time dilation makes sure that we're never able to pass light. If there was nothing else in the universe but your ship and light, you'd have no way of knowing that you were moving! How annoying is that?
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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.
Why do you humans always misquote Einstein. General relativity states that nothing can *accelerate* to the speed of light. It says nothing about things already going the speed of light. Experiments in Photon / Quantium Tunneling have indicated that photons can apear to tunnel through barriers faster then light.
There once was a lady named bright
Who travelled much faster than light
She set out one day
In a relative way
And returned on the previous night
Doesn't the emission of entangled-quanta already violate thee speed of light? I believe this was tested in the Aspect Experiment.
Also, I just took a course in the philosophy of physics but the one thing I never understood was how anything going was than the seepd of light would ruin Einstein's theory? If another THING was found that was faster as light and had the same speed in all inertial frames wouldn't that be sufficient? You could have THING-cones (where volume(THING-cone) > volume(Light-cone)at any time T --by volume I mean the fourth-dimensional equivalent), and things that are currently space-like seperated could be reclassifed as THING-like(for things faster than light but slower than THING) or space-like seperated (faster than THING), and this could account for the Aspect results. It also wouldn't need to violate the rule of not travelling faster than the speed of light since it could be mass-less and then as it approach and crossed C it mass would still be zero as opposed to approaching infinity.
IANAPhyisicist but IAALPhilosopher
Your CPU is not doing anything else, at least do something.
Unfortunately, black holes are sparse in this neck of the woods
_UN_fortunately?
Neither does the expense that goes into things. This is not intended to prove a point on its own, but the ratio of safe to unsafe launches is one point to consider; the number of unsafe launches, on its own, is another. In this case, "unsafe" is determined by Mother Nature proving it so.
If they've cut corners wisely, the fact that they've cut corners is less significant than some might want us to believe.
NB: YMMV. IANAL. Take the above with a grain of salt.
HTH.
Ground controllers could not verify the rocket had all its correct flight software loaded, and halted the launch.
I bet they're wishing now they'd kept the About box in the spec.
Why the name Gravity B? Was there a probe called Gravity A?
...John Titor, by chance?
Not per se; GPB is designed to detect and measure frame-dragging, independent of what any particular theory (such as GR) predicts for the magnitude of the effect. Of course, everyone expects the result to confirm GR's prediction, but that's a different matter.
What problem? Is this a problem you know they actually have, or merely one that you believe they probably have?
How is delaying the launch for 24 hours "suspicious"? It's still going up, just one day late. That's not bad for a project in development for 30+ years.
This isn't about "saving face", this is about sending up a working experiment. Sheesh.
> > Unfortunately, black holes are sparse in this neck of the woods
:)
> _UN_fortunately?
Well, in most necks of the woods they're actually rather dense.
HOO-ha!
---- I'll take you in a Hunt deathmatch any day.
Hm, you're wrong there. As your speed approaches infinity, your mass also approaches infinity. Thus, the energy required to accelerate you ALSO approaches infinity. Therefore, it would take an infinite amount of energy -- more energy than you could get, even if you converted the entire universe to pure energy.
:)
So, you'd have to already be traveling at, or greater than, the speed of light. It is impossible to accelerate past it. However, you're right that, even then, you would measure the speed of light as being exactly c faster than you.
I've read a lot years ago that said there was some basic proof they did indeed exist or could be artificially created or something. but it's been ages since I've seen a single word on this subject.
so if tachyons are real, then they do travel faster than light. remember, there's nothing in einsteins ideas saying you CANT travel faster than light, from what I remember its just basically saying you can't accelerate to faster than light.
but if you "jump" (warp, etc) or whatever, then you kind of side-step the issue, not really breaking the physical laws. I mean all sorts of weird things happen inside black holes that violate our natural laws (hence a whole new section of physics just for black holes). like time moving backwards, etc...
but really I'd be curious if anyone had any updated info about tachyons or the like? are they debunked now or what?
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.
Why do you humans always misquote Einstein.
:-)
Because schools nail silly ideas into people heads, and Einsteins book "Relativity: An Explaination That Anyone Can Understand" wasn't so easy to understand?
General relativity states that nothing can *accelerate* to the speed of light.
Err... I thought that was Special Relativity. General Relativity deals with the way that gravity works. i.e. Gravity is acceleration. Therefore, matter and energy must curve space-time to make a "downward" slope.
That being said, you have the "halfway" problem of accelerating to light speed. As you accelerate, time dilation increases. As time dilation increases, your engines are less effective to an external observer. Therefore it becomes a lot like drawing a line halfway to the destination, then drawing another line halfway of the remainder, ad infinitum. You'll never reach the end. And because your mass increases, you could only use a rocket (converts your near infinite mass -> energy) to make the transition. An external force like a particle accelerator doesn't have enough energy (infinite) to push you to light speed.
It says nothing about things already going the speed of light.
Correct. When a collegue of Einstein's suggested that it was impossible for an object with mass to reach light speed, Einstein felt compelled to point out that a photon has mass and it travels at light speed.
Experiments in Photon / Quantium Tunneling have indicated that photons can apear to tunnel through barriers faster then light.
That really has more to do with Quantum Mechanics than relativity. Overall, the photon is incapable of exceeding light speed. However, it can temporarily "steal" a bit of energy from nearby particles to tunnel out of existance and into existance elsewhere. The amount stolen is then payed back, resulting in a zero sum gain in velocity.
There are many things in this universe that appear to defy light speed. Unfortunately, not one of them is capable of transmitting useful information faster than light. Considering that this holds true at all levels of physics, one would almost conclude that the universe is out to "get" us.
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Here's a link for you on this oddity of relativity:
http://www.fourmilab.ch/cship/cship.html
Remember, everything is relative. All frames of reference are equally valid, and there is no "universal speeed limit". There is however, a universal time dilation limit. Once you reach light speed (impossible with a rocket or particle accelerator), you'll be forever frozen in time (just like a photon).
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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.
Saying "mass warps spacetime" doesn't explain how it pulls that stunt anymore than answering who was pushing Kepler's brooms.
Just how does mass warp space? How does space know the mass is around? What particle is gravity's carrier? If there is a gravity particle, how come planets don't speed up as they plow into them orbiting the sun? And how come it gets to escape black holes but no other particles can come out and play?
I find it really weird that here we are 400 years after Kepler and Newton figured out planetary motion and we still don't know what the heck makes it work. We can describe gravity's effects but we can't say how it does the trick.
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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.
I think it was appropriate:
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.
The man's been dead for decades and now someone wants to "probe" him? What kind of sick world are we... errr... ohh... (hahaha)... oh, you mean a SPACE probe. [shuffles offscreen] ;p
Un-news
He still cannot accelerate to or past the speed of light.
:-)
You're missing the frame of reference. Yes, you can't actually *catch* light. Light speed will always be light speed. But from a frame of reference on a rocket ship experiencing time dilation, you can most certainly accelerate to a speed that would *appear* faster than light.
So thanks to time dilation, I can make it to Alpha Centauri in 6 months. But to everyone back home, it took me 4 years. Which one is correct? The answer is that both are. To the observer on board the ship, he's traveled 8 times the speed of light without ever passing a photon. To the observers on Earth, he's never gone faster than light speed. You see, it's all relative.
An interesting aspect of our universe is that every particle is already traveling light speed. (It's in Elegent Universe. Go ahead, look it up. I'll wait.) The trick is that our trajectory is in 4 dimensions. By traveling faster in three dimensions, we travel slower through the forth. i.e. Everyone on our slow planet is aging very quickly. We just don't know it because we have no other frame of reference. But if you speed up to 99.99% of c, you will age much more slowly than people on Earth. The reason is that you are now traveling slower in the forth dimension.
If this isn't making sense to you, then you need to reread Elegent Universe.
Bonus link on the Speed of Light.
Interesting tidbit: Einstein called his theory (in original German) "The Theory of Invarients", since the speed of light was constant in all frames of reference. It was an english speaking collegue of his that dubbed it "Theory of Relativity".
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Where to Publish Your Paper
- If you understand it and can prove it, then send it to a journal of mathematics.
- If you understand it, but can't prove it, then send it to a physics journal.
- If you can't understand it, but can prove it, then send it to an economics journal.
- If you can neither understand it nor prove it, then send it to a psychology journal.
- If it attempts to make something important out of something trivial, then send it to a journal of education.
- If it attempts to make something trivial out of some-thing important, send it to a journal of metaphysics.
I'm sure folks can add a few items suitable to this conversation and Slashdot."It is a greater offense to steal men's labor, than their clothes"
Actually, at the speed of light, traveling towards the arth from Alpha Centauri, light from Sol would be traveling at 600,000km/sec in relationship to him.
You're off by a factor of 2. Light travels ~300,000 km/sec to all observers.
Light originating from his ship would be travling at normal speed to him, but faster or slower in perspective to anyone (or anything) he was passing.
Nope. Light originating from his ship would travel ~300,000 km/sec to him and anyone else who might be watching.
So, the speed of incidence would be Pa + Pb, which to either photon would be rather high.
That's Newtonian physics, which Einstein disproved. The speed of the photon will always be Pb. Have you read "Elegent Universe" yet? It's the best explanation I've ever seen. In short, we're all traveling at light speed through four dimensions. By traveling faster through space, we travel slower through time. This scales so perfectly, that we will always measure light as going ~300,000 km per one of our current seconds. We may actually be reaching 99.9999% of the speed of light, but it will seem to us that light is still traveling at ~300,000 km/sec. If we manage to obtain light speed, our time dilation will become infinite and we will forever be frozen in time. Thus photons never age, because they expend their entire velocity in only 3 dimensions.
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Not really. The main motivation for the general theory was simply that Newtonian gravity (or more specifically, the Newtonian gravitational potential) failed to make predictions which agreed with observation. The most well-known example of this is the precession of perihelion of Mercury. If you're referring to the fact that Newtonian gravity imposes no upper bound on velocities, then you're correct, but this was more an illustration of the fact that Newtonian gravity was largely irreconcilable with special relativity.
Nope. I am afraid that the parent was correct and that you may have misunderstood him.
Einstein's motivation for GR (General Relativity) was that SR (Special Relativity) is inconsistant with NG (Newtonian Gravity). NG does indeed predict faster than light effects. If you wiggle a particle on one side of the galaxy, then a particle on the other side would feel that immediately.
This is a theoretical motivation, and not a physical motivation. Once you have SR, you immediately have to fiddle with gravity. He would have had to do this even if we had no conflicting evidence against NG.
A Usenet Troll Triumphs on Slashdot
No, I think you mean:
1) Bad result, but your graduate advisor yells at you. This is not a successful experiment.
2) Good result, but your graduate advisor takes the credit for it. Your advisor might consider this a successful experiment, but then he also calls you his "lab bitch" at faculty luncheons. Call it a draw.
3) Good result, but you will be unable to reproduce it ever again. Like the fabled WOW! event in radio astronomy, this tantalizing glimpse of success will haunt you through your waking hours, spent alternately drinking and working as an assistant manager at Radio Shack.
4) Bad result, but your graduate advisor is "accidentally" vaporized in the process. Although not strictly a successful experiment, you hear no complaints from your fellow grad students, the surviving faculty members, or the long-suffering department secretary as you are lead to the police car, leaving your former lab (and former career in academia) in glorious, if somewhat radioactive, flames.
Hope this helps!
to probe Einstein, even if you're a necro, and that's just gross.
WWJD? JWRTFA!
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....
There are many things in this universe that appear to defy light speed. Unfortunately, not one of them is capable of transmitting useful information faster than light. Considering that this holds true at all levels of physics, one would almost conclude that the universe is out to "get" us. :-)
Maybe it's the other way around -- a hard speed-of-light barrier essentially makes interstellar war on any scale impractical. This could be why we're still here and not a Borg colony. It won't stop us from colonizing this system, and in the long run won't prevent colonizing with generation ships, but unless aliens have a much longer life- (and attention-) span than us humans, they're not going to bother attacking us.
Mal-2
How is the Riemann zeta function like Trump rallies? Both have an endless number of trivial zeros.
Maybe it's the other way around -- a hard speed-of-light barrier essentially makes interstellar war on any scale impractical.
Poppycock! If you had colonies/armies that always traveled at high percentages of c, then they'd all be within similar enough frames of reference that they'd be able to easily carry out wars. To everyone on a "slow" planet, a war would take anywhere from hundreds to millions of years, but to the factions fighting it's all happening within real-time.
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Ken Thomposn built Gravity B as a constrained version of Gravity BCPL. Once K&R got their hands on the technology and added a type system, they were ready to launch Gravity C. Gravity C++ soon followed in an attempt to incorporate Quantum Mechanics.
/. articles, there is much talk about Gravity D; hopefully it will have some nice black-hole garbage collection.
A perfect SuperString implementation has yet to be added to the language, although many incompatable approximations exist.
As we know from recent
Correct. When a collegue of Einstein's suggested that it was impossible for an object with mass to reach light speed, Einstein felt compelled to point out that a photon has mass and it travels at light speed.
Photon's have zero rest mass. The only mass they have is a relativistic consequence of their velocity.
M.
Forgive me if this has already been stated somewhere else by someone better qualified, but I was too lazy to keep scrolling down. Oh well...
Sure, it'd be possible to send armies of men (or whatever) and machines at near-lightspeed, and take advantage of relativistic time-distortion, but no matter the outcome, it'd be a one-way trip. Even if they ever won and returned home, it would be to find a world to which they no longer belonged. I can't think of many people patriotic enough to want to cut themselves off from everything and everyone, no matter the threat.
On the other hand, if you really, really wanted to fight a war across interstellar distances, why bother with living beings at all? Just send some sort of handy self-replicating machine-thingy their way and wait. You really only need to send one automated factory, with maybe one as a backup. It arrives at the destination years later, starts cranking out whatever machines and vehicles it needs using stuff from asteroids or comets or whatever, and eventually wipes out the enemy. If you have the capability to build a self-replicating factory and then send it across interstellar distances in the first place, designing one smart enough to fight a war on its own wouldn't be very hard.
...but also whethere or not mass bends space/time. The probe was designed to test for both, and includes a set of gyroscopes for this purpose. These contain the most spherical spheres ever constructed. The mass bending thing was to be tested by measuring the length of the orbit. If an inch is 'missing', mass bends space/time. Imagine if massy objects were placed on a sheet that was anchored along the edges. They sag into the sheet. An object orbiting one of these objects now has a shorter distance to travel than if the objects did not cause the sheet to sag.
I have all the answers. You just ask the wrong questions.
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
The problem with GPB is that it measures a pretty uninteresting effect and takes a lot of money to do so.
Why is the effect uninteresting? According to the parameterized post-Newtonian (PPN) formalism, which describes most reasonable extensions of Newtonian gravity, frame dragging is a combination of only two effects: the amount of curvature of space caused by matter and lack of spatial isotropy, each given by a parameter. In GR, those parameters are 1 and 0, respectively.
Now, we know the amount of spatial curvature caused by a mass. With that, frame dragging of the amount predicted by GR is pretty much a given unless there is significant lack of isotropy.
So, GPB becomes a very expensive test to see whether space is isotropic. But even at that, GPB isn't a very good test: if its results disagree with General Relativity, we learn something, but that result is very unlikely and there would be better ways of looking for anisotropy. If GPB's results agree with GR, however, we have learned nothing, because there are many ways in which this particular experiment could fail to observe anisotropy even if it exists.
GPB's results should agree with GR. If they don't, then the most likely explanation is an engineering mistake. If they do, GPB will be hailed as a great "confirmation" of GR, although in reality, we will have learned nothing.
Simply put, a massive object like a spaceship cannot travel faster than light since it would require infinite energy.
..and thanks to people who so much believe in ancient fairy tales that they want to outlaw anything that would threaten their own way of living I might be forced about 50 years from now to stop pursuing what I think is the meaning of life: wisdom and knowledge.
However, this only applies to POSITIVE energy density (=mass) of the spaceship.
An advanced civilization could collect enough negative energy from for example a large array of very powerful lasers using spinning mirrors to make one of their spaceships to have NEGATIVE MASS.
With a negative total mass when accelerating it's mass would increase ever getting closer to 0 and when moving at c the mass would be exactly 0. After that, it could gain more speed (and positive mass from velocity - rest mass would of course still be negative) just like photons can temporary move faster than light (for example tunneling).
One notable feat of this level of technology is that it would allow them to freely enter and exit event horizons and view the singularity. Also, time travel would naturally be trivial as well as practically limitless lifespans but I assume that this level of species had already made itself immortal a long time ago - one of the major reasons that history seems to repeat itself here on Earth is the very short lifespan of the current dominant species of this planet.
Capitalization is the difference between "Helping your uncle jack off a horse" and "Helping your uncle Jack off a horse"
If a photon had mass, it would appear to have infinite mass when travelling at the speed of light.
Infinity. Not good.
# cat
Damn, my RAM is full of llamas.
Einstein breathes a sigh of relief as the box of rubber gloves is placed back into the drawer.
"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?"
The question that interests me more is: doesn't *anyone* know how science works anymore? The only failed experiment is one with *no* results.
If frame dragging is not observed, then lots of scientists will be trying to work out why. Did the experiment measure what we thought it would? If yes, what do we have to do to contemporary physics (which is a pretty darned good fit to observed reality) to account for the result? If no, what did we miss?
(I'm now thinking of the hoary old joke about the cub reporter who came back from a society wedding to tell the editor that there was no story because the groom never showed up.)
The probe was proposed 35 years ago, but has never had the funding until now.
I don't know whether to laugh or cry.
"Funding" was never a problem for this pig. It's been sitting in the middle of NASA's Office of Space Science budget for well over a decade, burning money at a rate totally out of proportion to its supposed science return, and compromising funding for other much more interesting astrophysics and space science missions in the process.
NASA OSS and the astrophysical community have repeatedly tried to get GPB cancelled, but the California Congressional delegation has kept it alive as a pork offering to Stanford, and to California's moribund aerospace industry.
The reason GPB is finally being launched is not that it is ready -- many people at NASA headquarters fully expect its systems to fail in orbit, as they repeatedly did in lab testing. It's just that it's cheaper to launch the fucking thing than to let it sit around for another decade, burning even more of the dwindling supply of cash that NASA expects to spend on actual science (as opposed to Buzz Lightyear adventures on Mars).
I only hope the perpetrators of this travesty of peer review don't attempt to inflict a "Gravity Probe C" upon us.
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