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Solar System in a Can May Reveal Hidden Dimensions
dylanduck writes "A model solar system, made of tungsten and placed in space, could reveal hidden spatial dimensions and test alternative theories of gravity. If the system's 'planets' moved slightly differently to the way predicted by standard gravity, it would signal the presence of new physical phenomena." From the article: "Once at the Lagrange point, the artificial solar system would be set in motion inside the spacecraft. An 8-centimetre-wide sphere of tungsten would act as an artificial sun, while a smaller test sphere would be launched 10 cm away into an oval-shaped orbit. The miniscule planet would orbit its tungsten sun 3,000 times per year."
This sounds mighty dubious. The gravitational attaction of the spacecraft is likely to be much larger than the effect looked for.
If the minature solar system is sent into space, then would it also come under the effect of the gravity of the actual solar system? Granted the effect will be very small (considering one object is very small and is far away anyway) but surely it would cause enough of an effect to make a difference? I'm sure they're trying their best to cancel out these forces, but they'd need absolutely minute amounts of gravity or (impossibly enough) none at all for a good reading.
If we can hit that bull's-eye, the rest of the dominoes will fall like a house of cards... Checkmate.
You would need to be extremely precise for that to work. The masses of the model planets would have to be PERFECTLY scaled. Do we actually know for a fact the masses of all the other planets, and can we make something that precise?
Then you have to consider the gravitational effect of the asteroid belt. Do we know the mass of that, too? That might affect the model when put in use.
Any conclusions made from this experiment would be debated over endlessly because of this...
"You teach a child to read and he or her will be able to pass a literacy test." - President George W. Bush
I wonder if our universe is just a hidden spacial dimension test for a super-advanced alien civilization... still trying to figure out string theory.
A tungsten sphere 10cm in diameter would have such a tiny gravitational field that I suspect even a hydrogen atom at the ambient temperature of local space would possess escape velocity.
What exactly are they thinking of putting into orbit around this thing?
I got black text on a mostly black background. Sheesh! The printable page reads a lot better.
Flyboy 8v)
I might be indecisive, but I'm not really sure. What do you think?
So they've got that much of it thought out. But in regards to the mass of the spacecraft carrying this jar:
So while they're full aware of the problems the mass of the craft can cause, they seem to think it's possible to minimize the effects to a reasonable level.
My question is, aren't Lagrangian points going to start to get a bit crowded? There are only five to work with in our neighbourhood and who gets to say who uses which and for how long?
...Cavendish's classic experiment. I look forward to seeing the results.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
But can anyone explain to me why gravity would be the only force bleeding into other dimensions? Or is it the only one? Also is there any evidence of extra dimensions already? I would think there would already be some evidence since it does not sound very scientific to me to base the very popular string theory on imaginary notions with no basis in reality. If we are just gonna make up dimensions to make the math work isn't that just as bad as making up Thor to explain the thunder and lightning?
I don't like the word choice "hidden". Hidden is the past participle of hide.
/endrant
"hide"
v. hid, (hd) hidden, (hdn) or hid hiding, hides
v. tr.
To prevent the disclosure or recognition of; conceal.
This fairly clearly implies intelligent action. I.E. something did the hiding. I.E. the dimensions we can't see (if they exist) are purposefully invisible to us because something chose for them to be, something intelligent. Invisible, as another word choice, would've been better.
Besides, something can't be hidden and yet physically interact with the universe. I believe if a thing interacts with the universe on any degree then we should be able, generally speaking as intelligent beings, to see it. And if we can't see the interaction, despite being able to probe to fundamental scales (planck, anyone?), then, forgive me again but, so fucking what?
So to me the word is not only implying an intelligent purpose, but is furthermore illogical in choice from the very point of view of physics.
Maybe I'm full of shit, I probably am. I guess the real reason I write this is that I'm really starting to get tired of people throwing around buzzword catchphrases like 'hidden dimensions' to get attention. You might as well say the UFO's made them. Anyway, explain to me how something that can be measured via our three standard directional dimensions manages to slip into the realm of 'hidden dimensions'?
TLF
I do not respond to cowards. Especially anonymous ones.
"Well, we're running an experiment to see the effects of gravity on these little screws."
"Well, good luck finding a judge that doesn't run a bestiality site."
No big deal, plenty more scientists where they came from. I'd be more concerned about them creating a great big black hole, and us never being heard from again.
The higher the technology, the sharper that two-edged sword.
The key question is: What is the ratio between signal and noise here? The article does not mention this at all except talking about lagrange points, solar wind, etc. I assume placing it at L2 is to get the S/N ratio >1.
This fails when considering some noise sources:
1. Accelleration felt by a "grain sized planet" due to a 5kg ball 10cm away is 1m/s/year.
2. Acceleration felt by same "planet" due to moon 1 million kilometers away: 130 times more
3. Accelleration felt due to spaceship: ?
4..? L2 orbit itself, light pressure, magnetic & other fields etc
This appears unfeasable by orders of magnitude.
I do not have much faith in statments like "Gravity leaks into other (higher) dimensions." Where does this come from? Efforts to make string theory models fit the real world?
"Fix it"
Would the fact that this little universe would be enclosed in a spaceship have any effect on it?
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If you can read this sig, you're too close.
Gauss's Law says that the gravitational acceleration of a body anywhere in an enclosed sphere is 0. At L4, L5 Earth and Sun graviational forces are balanced. The only accelerations that don't cancel out are the two body accelerations of interest. It is surprising to me that the bodies orbit as fast as 10 times per day. I wonder why they don't use heavier Uranium as the mass. It is an interesting side note that a body can stably orbit one of these points. They orbit with no body (!) at the focus. The Genesis Probe and WMAP missions have already taken advantage of this.
an ill wind that blows no good
Since we're not able currently even to build a spaceship capable of making it to the moon (having mothballed all the relevent tech and gone for the technical nightmare that is the shuttle, and the hidiously expensive disaster that is the ISS), why bother with these types of experiments?
Such experiments, while useful, aren't practical when we have a real and current need to figure out how to get construction workers and ordinary people into space, so we can build a realistic presence there.
Once we're there, we could perform experiments like this at a fraction of the cost.
Ok, perhaps I'm thinking too fancifully, but it's real concern. Let's face it, every environment we've moved into only becomes liveable when the ordinary people who know how to build stuff and make things arrive. The larger the number of people, the faster things progress.
So long as it's only scientists and the 'elite' going into space and performing experiments progress will be very slow. That can't be good.
What we need is people going 'prospecting' for interesting asteroids/orbiting 'junk' that can be exploited, building commercial stations, setting up routine flights into space. In short, we need economic forces active in space.
It seems to me, after reading the article, that there are just too many influential factors to be able to conclude anything by such a test. From the article If gravity is leaking into extra dimensions, the slight change in its force should cause the planet's oval-shaped orbit to rotate, or precess, slowly... the orbit would precess by 1/3600 per year - "a reasonable quantity to try and measure," they say.
I wonder how they could conclude that a change of this magnitude would come from gravity leaking into other dimension and not from any of the other myriad of possible effects. It is a good idea, I just don't see how it could work.
I nominate this for the strangest news article title of 2006.
Beware: In C++, your friends can see your privates!
Ok, some orbital mechanics.
./3000 = 10518.912 seconds per orbit .00009506686623103225 orbits per second
.*.14*3.1415926*2 meters per orbit =
.0000836 meters per second
.*1000 = .0836 millimeters per second
.000268 m^3
.*19250 = 5.16 kg .004 m in radius .000000268 m^3
.*19250 = .00516 kg
.00000000006673000000 * 5.16 * .00516 / (.1*.1) .00000000017767262800 Newtons of force, resulting acceleration on the smaller body of
./.00516 = .00000003443267984496 m/s = .00003443267984496 mm/s
.0836 millimeters per second everything should be fine!
Going with a circular orbit because they didn't specify the ellipse:
365.24*24*3600 = 31556736.00 seconds per year
1/. =
Pretty slow orbit. About that tungsten, 19250 kg/m3
3.1415926*(4/3)*.04*.04*.04 =
And let's say the planet is 8 mm in diameter,
3.1415926*(4/3)*.004*.004*.004 =
F = G m1 m2 / r^2 =
gravitational constant = 6.67300 × 10-11 m3 kg-1 s-2
=
Sounds reasonable to me. Assuming they can get a clean launch at exactly
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Wouldn't the space ship exert its own gravity on the system and ruin the whole experiment?
Once at the Lagrange point
Lets review this. Lagrange point. Last I checked, a point is not a "region". So there's no way to put a titanium anything completely within a Lagrange Point. At the very best they might put the "sun" part of it centered at the LP, but then the "planetoids" would all be outside the LP, and however minorly, would be affected to varying degrees by the gravity of the earth and of the sun.
This test is invalid. The use of a LP is not going to nullify the effect of gravity of the earth, let alone of the sun. If they are going to do a test that is this sensitive, there is nowhere in the solar system they can hold it and get accurate results.
I work for the Department of Redundancy Department.
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Read my first reply to my comment for more clarification if you want. But as per your comment here, the surface integral of the vector field (dot producted with its infinitesmal area element, of course) is identically zero for any surface enclosing zero net source/sink density (ie, masses or charges). Just because this surface integral (ie, a continuous sum) is zero doesn't imply the local vector field at any point on or within the surface will be zero. As perfectly exemplified by my brick example.
And finally, the gravitational field within a hollow sphere is zero only if the gravitational field is also zero in the absence of that sphere.