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Measuring Gravity in Your Basement
Jack Durian writes "John Walker, the founder of Autodesk/co-author of AutoCAD has some fun playing pretend experimentalist, measuring gravity in his basement."
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I haven't got a basement. Help.
John says that gravity is an incredibly weak force. John should have said that Newtonian Gravity is weak. Relativity says in space, that acceleration and gravity can essentially be the same thing. Gravitational fields are also known to bend spacetime. Thus, if you have an object with a high enough density, the gravitational field around it accelerates you to close the speed of light. This also in my view, contradicts Johns view that "gravitation is the weakest".
"I would go to the building superintendent and
offer him a brand-new barometer if he will tell me
the value of G"
McCartney fans pay bus tickets. [...] Lennon fans too, with discretion.
The article doesn't mention (iirc) how you account for an minimize the effect of electromagentic forces. Is it the material you choose. I suppose if you juxtapose the spheres and the attraction is the same you have accounted for it (because of polarity).
It is by coff... er, will, alone I set my mind in motion...
How could we let a traitor like John Walker tell us how to measure gravity.
It's unamerican!
Blaze a trail to the New World
Put a ring of optic fibre on one of the arms and pump laser light into it. Measure how long it takes for the arm to respond. Lesson: Mass and Energy bends space time.
How we know is more important than what we know.
John Walker come up with a device to measure the Density of Larry Elison?
If not, then as pointed out on the web page, the relative strength of the electrostatic force (which is also inverse square) is far larger than the puny force of gravity and it could swamp the measurement.
For your information, a common way to measure G (the gravitational constant) in the lab is by using an oscillating torsion balance and detecting the frequency change due to the introduction of large masses in the vicinity.
What the heck is a dyne anyhow, what's wrong with good old' SI? NIST for those interested there's a converter between all the old interesting things like the pole, perch, hogshead, American mile, British mile, American short ton, British long ton and various other devients of the mind Here
Be nice to people on the way up. You will meet them again on your way down!
The gravitational constant is an elusive thing. When I studied quantum physics, the lecturer, who was one of the members of the Nobel Prize committee (I live in Sweden), told us that one of the "sure" ways (there are a few grand questions in physics which has this status, others probably include: finding the mass of neutrinos, evidence for the Higg's Boson, the decay time for protons, etc) to get a Nobel Prize is to measure G as exactly as the other physical constants are known (i.e roughly to the same number of significant digits).
Opinions stated are mine and do not reflect those of the Illuminati
If all this should have a reason, we would be the last to know.
What blows me away isn't the fact that he demonstrated gravitational force in his basement, it's the second demonstration that showed how Archimedes (or any other Greek natural philosopher) could have done the very same thing with sticks, string, and stones. Incredible! I've always been very, very intersted in history and raw information (or, generally, the lack of it). It's pretty well been shown that the Egyptians could have created a pretty powerful computer using fluidics bricks, and that the Chinese could have build hang gliders using silk and bamboo. Now it turns out we could have had Newton 1900 years earlier. Amazing how much difference just a little bit of knowledge can make.
Serving your airship needs since 1995.
I have trouble believing this setup will work, because
Experiments today are done with a Cavendish apparatus, which very similar to the one shown. Here's a link with some pics.
This is unreserached thought, so don't come down on me too hard. I am just recalling from my youth
vossman
I agree with this in a sense, and my answer is part philosophical, and part semantics. In fact, there IS a natural _physical situation_ that you mention. This situation is one where all the physical variables take one unit. That is the mass of the interacting particles is one unit mass, the charge is one unit charge, etc. But what units does one use? One uses the most PHYSICAL units. Charge comes in bundles of charge quantized at e, so measure charge in e. c (the speed of light) is constant in all frames, so measure speeds as fractions of that, etc. So now, by using particles with unit values in this system for all relevant quantities, one gets a NATURAL (that's the semantics/opinion) system. Natural == the interacting objects are fundamental physical objects moving according to fundamental physical trajectories. So, off of that tangent, the gravity in that situation is the weakest force; and the usual textbook ranking of the forces holds.
Man, this Walker guy sure keeps busy, he's a Texas Ranger, a Taliban, he's a scientist...wow!
You can't take the sky from me...
So what's the "natural" fraction of c? 1/100? That'd be just an accident of our having 10 fingers.
And what's the base unit of mass? A solar mass? Seems natural to me, as an astronomer. In that case, gravity wins. And length? You could claim Plank units, I suppose, but they're not really tied to anything physical, as such.
So before you compare, you need an actual situation set up to look at. This isn't like saying "Blue light has a shorter wavelength than red light." That statment is always true, totally meaningful and useful. Saying "Gravity is weaker than electrostatic forces," is often untrue, not really well-defined in meaning and (being untrue in so many situations we encounter) not useful.
The trouble here is that people just have this inate itch to rank things, even when any such rankings can only be made on a case-by-case basis.
I just want to let Slashdot know that the stories in the Science Section are interesting and dont assume that they are not popular seeing the meagre number of comments for it. This is just because news in the area of Science are not as conducive to debates, personal views/opinions, and everything that pushes along the comments, as compared to other stories.... Slashdot readers in general like the Science section and like to read its stories. So let the Science section continue in the near future....!
I have found a solution to Riemann's Hypothesis, but have run out of spac
Everybody knows that... However g is not the same as G. G is the universal constant that governs all gravity and that is what we need to measure. There is nothing fundamental about g.
Opinions stated are mine and do not reflect those of the Illuminati
From the article:
Most misleading headlineAnyone else notice the size of that stone age beast of a spider next to his experiments? I wonder if that was a calculated variable?
If you're looking for accuracy, you'll have to perform the experiment at least a hundred miles from any type of human civilization, including any streets with cars driving by. Also make sure no planes fly by anywhere in the area, and that there's no wind outside to create vibrations of any sort.
You want to see what Gabe Luther and and William Towler,current "holders" of Big G, used to measure it ? Here's a great shot of the torsion balance device from this short summary .
Here's a link to the press room at LANL Look for "17) Measuring the Gravitational Constant ("Big G") -- In the Lab of Gabe Luther, Los Alamos scientist. Sound bite on methodology." - no link but an interesting page of resources.
"Whoever would overthrow the liberty of a nation must begin by subduing the freeness of speech."--Benjamin Franklin