Slashdot Mirror
NASA Gravity Probe Launched
ping pong writes "Forty-five years in the making and 24 hours late, NASA launched the $700 million satellite into orbit today to test Albert Einstein's general theory of relativity. The satellite, which was inserted into a polar orbit, will spend two months getting ready, then 16 months making measurements." NASA's mission news has more.
The greatest men are those who keep shaking up the world even after they are long gone. Albert Einstein wasn't a businessman, or a soldier, but look how much research and spending has been affected by his findings. Kudos!
Every other test of Relativity has not yet disproven it, they've all fallen within predicted values plus/minus experimental error. It's unlikely this one will fail. If it fails, it just means one aspect of the theory needs revising.
Not that that will stop a thousand woo woo's trumpeting that their theory predicted this 120 years ago.
Wouldn't our understanding of something as fundamental as general relativity far out weigh any kind of understanding we could gain from Mars? Even if life is found on Mars, it does little to solidify our understanding of the fundamental forces of the universe.
Gravity is one of the most important, and least understood forces in the physical world. Mars is just a big rock in orbit around our tiny little sun. Going there is a cooler project that this, but the information garnered from such a mission seems to be less important than what this mission is set to show.
although it seems like a lot of money to spend just for testing his theory
I think it's really a cheap experiment, considering the importance of the results. If there's something wrong or incomplete in Einstein's theory, we (as in humanity) should know about it, firstly because it's the human nature to try to know more all the time, and secondly because it could be very important in practical terms: you wouldn't want to take a plunge off a cliff with your SUV because your GPS receiver had a slight error, would you?
This is theorical science and experimentation at its best. The price is really cheap to advance mankind's knowledge. Compare this to the weekly cost of certain recent military activities that probably won't bring back much to mankind anytime soon...
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
All quoting aside, I wonder what will or would happen if the theory of relativity turns out to be nothing but bunk. It wouldn't be the first time our scientists knew something, even if it were based partly on observation. I'm no physicist, but I know Einstein's made assumptions that haven't been proven wrong or right, for example the speed of light in a vaccum is the fastest attainable speed in the universe. Just because we haven't doesn't it doesn't. And what about the unexplainable increase in velocity of the voyager probe as it neared the edge of the solar system? When I read that article, I remember thinking "wouldn't it be great if I was alive to see such a monumental discovery, along the lines of 'the earth ain't flat no more'?" I think it'd be so cool (ok, interesting) if this experiment means we need to rewrite our laws of gravity.
Gravity is a force that effects everything in our universe (and in theory some other universes :P )
:)
It's a force we can calculate for and predict but we still aren't completely sure HOW it works. So whether this mission proves or disproves Einstein's theories we should at least get data that will help bring us a step closer to understanding a significant force in the universe.
I'm really exicited to see the results in 2 years
For the long duration it took to complete the project, I don't think it was *that* much money per year really. I don't think $15 million / year is much in the big picture.
Beware: In C++, your friends can see your privates!
it seems like a lot of money to spend just for testing his theory. I think that recent missions to mars were a bit more interesting.
That boils down to less than $3 per American, spread out over the last 40 years.
To prove conclusively (or not) our most fundamental theory of gravity, space, and time.
Man, you are a cheapskate.
I really don't think the financial analysis is the correct one. I'm fairly sure the US will derive enough benefit to justify the cost, although the benefit is admitedly difficult to quantify and is amortized over the rest of our specie's existence. Does it matter if the rest of the world gets a free ride? They do pure science too, and we benefit. Science is a collaborative effort. This isn't some billion dollar defense department project seeking a military advantage over a perceived adversary. This is about scientific discovery and learning things that have never been known. In my cynicism concerning politics, I sometimes forget to be optimistic about the science.
>> My ultraviolent Linux switch video.
That the hope of theoretical physicists is to unite gravity with the other forces, understanding the why and how of divergance, and hopefully uniting quantum dynamics with general relativity (properly fund NASA!, GWB) creating one theory to explain them all.
Needless to say, much will need to be discovered even after a successful GP-B mission.
Marx didn't propose death squads or any other form of tyranny. That's like blaming George Bush on George Washington.
The darkness... controls the music. The music... controls the soul.
So, if it's impossible to implement what Marx proposed with homo sapiens how exactly did it kill about 100M people?
//Blessed are they that run around in circles, for they shall be known as wheels.
The question isn't whether the experiment should be done, but should it be done *now*. Is it worth 700M to do it *now* compared to 70M in 50 years when it would be cheaper to get high precision instruments and to put things into space.
D6 63 0D 70 89 81 BB 8E 7B 7C 5F 5D 54 EA AB 73
There's a question I wanted to ask the last time this probe was discussed on slashdot, but alas I discovered the discussion too late to be assured a viable discussion.
Is the presence of frame dragging a forgone conclusion, given that (a) gravity waves do not travel instantaneously, and (b) the moon is able to maintain a stable orbit around the earth, even though the earth itself is in motion?
My college physics were limited to 2 semesters, but I do recall discussions of a velocity component to gravity. To use more severe example than the earth and moon:
Pretend, for simplicity's sake, that the earth's orbit is circular, and is exactly 8 light-minutes in radius. By the time gravity waves reach the earth from the sun, 8 minutes have transpired, and the sun is certainly no longer in the same spatial position that it was 8 minutes prior. This means that earth is no longer orbitting what it "thought" it was orbitting (if you'll excuse the tongue-in-cheek anthropomorphization.) The only two ways I've ever heard of accounting for this are:
(a) gravity waves are not limited by C, and in fact gravity's effect is felt instantaneously
(b) there is a velocity component to the effect of gravity, that takes into account the speed and direction of travel of the object(s) involved.
I think (a) is pretty much out of favor, right? If so, that leaves (b). Thus, velocity matters... regardless of whether that happens to be linear or angular velocity.
Since rotation is angular velocity... does this not imply that frame dragging exists?
I'm definitely interested in replies from Physics whizzes on this one... it's bugged me for a while now.
HSJ$$*&#^!#+++ATH0
NO CARRIER
Interesting schminteresting. If you invent a flying car, and someone builds a flying bomb to subsequently claim it's your flying car and fly it into a crowded marketplace, was it your invention that killed those people? And indeed, Soviet Russia wasn't true communism. It was statism with communist ideals painted on the sides.
... I suspect it will be more of a testament to the power of experimental precision rather than a test of GR, which practically every serious physicist believes to be correct.
Err... I don't think so... every serious physicist strongly believes that relativity laws are an excellent model of the behaviour of the universe in the macroscopic scale.
Science is inherently an asymptotic quest for the truth. Any serious scientist knows that.
This is complete troll, however, if you actaully think that, you should look into what Marx actually did say.
Im not going to go into it now, however, his ideas have almost never used. There has arguabley never been a genuine Marxist/Communist government. Possibley in Chile, for a short while, under Salvador Allende, untill the US killed him (and put Pinchet in charge to rape the country, and kill whomever he pleased).
Sure, many people argue that communism wasn't "true" communism as Marx defined it.
Amigo, it had nothing to do with it. Trust me. Zero.
"Thats right buddy, the large print giveth, and the small print taketh away."
Not that I think the science isn't valid enough for NASA to afford this (they've obviously got money to burn) but isn't NASA trying this on as a means to validate their science budget from which they feed?
The manned spaceflight missions have always had the justification that understanding the effects of zero gravity on humans over extended periods was sufficient to secure funding from the NSF and others but zero-G on humans has been tried and tested over the past 40 odd years and is no longer considered of interest to fundamental science.
The timing seems to indicate that NASA wants to show it can carry out fundamental science experiments even if the results aren't relevant to modern questions in fundamental physics. They even go so far as duplicate well accepted results in a field that has progressed well beyond the best precision of GP-B.
The only way this probe will really teach us anything (outside of the engineering that went into its construction) is if it fails, spectacularly
Considering the price ($700 mil), I think any failure would be considered spectacular. Spectacularly bad. At least we will get some fireworks when it re-enters, no matter what.
If you open your mind too wide, people will throw trash in it.