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Gravity's quantum leaps detected
New Scientist ^ | 19:00 16 January 02 | Hazel Muir

Posted on 01/17/2002 4:06:29 PM PST by Ernest_at_the_Beach

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To: PatrickHenry
Heavier objects falling faster than lighter objects?

I agree: if for no other reason, because the heavier object ATTRACTS the other body more, which will have a small but real velocity component up towards the falling object!

51 posted on 01/18/2002 8:56:42 AM PST by chilepepper
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To: laconas
maybe in some time they will able to measure the speed of gravity

A repeat in a way of the Thompson experiment where the charge on an electron was measured.

What is the speed of electrical attraction?

52 posted on 01/18/2002 9:02:01 AM PST by RightWhale
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To: Askel5
So you pigeonhole others ("math", "guy") and then declare yourself the queen of noncompartmentalized thinking. "Clever" "Girl".

I agree that this experiment doesn't directly address other energy levels (although it handles the edge condition). The effect will be less at higher energy levels. As an analogy, the two-slit experiment (the hypothetical, intro quantum theory experiment that shows that electrons appear to be in multiple places at the same time) is done with particles, where the effect can be noted, not baseballs.

Physical theories can be verified under different conditions, but not proven in the mathematical sense. Remember Mr. Spock's: "We may be in a region of space where our physical laws do not apply."

BTW, to show I'm not all "math" and "guy", I saw "The Music Man" recently. You came to mind when the mother blames her daughter's singleness on "her Irish imagination, her Iowa stubborness and her library full-of-books."

But I forget why.

53 posted on 01/18/2002 9:15:41 AM PST by monkey
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To: monkey
Oh man ... there's gonna be trouble in river city if and when my mother checks in to see what the clever monkey had to say this time.
54 posted on 01/18/2002 9:18:34 AM PST by Askel5
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To: Clarity
Well, I'm not sure what you're looking for in the way of proof, and I'm not sure what you mean by 'minimum necessary energy levels'.

The reason you can't tell that the energy of, say, a baseball is quantized is because the energy levels are so close together at that energy scale. In order to see the quantization, you need to look at extremely light objects that move slowly.

If the spacings were much, much farther apart, you might notice that while you can throw a baseball upwards at, say, 10 mph, which allows it to reach a certain height, you can't throw it upwards at 12 mph. Put a little more arm into it, and you can throw it at 14 mph, but not a little bit faster or slower than that. Put still more arm into it, and you can throw it at, say, 17.5 mph.

But yes, I suppose in the real world, you wouldn't be able to demonstrate energy quantization in the case of a baseball, since you'd never get the resolution you'd need. But lighter, slower objects do apparently behave in the counterintuitive way I described.

55 posted on 01/18/2002 9:22:33 AM PST by Physicist
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Comment #56 Removed by Moderator

To: laconas
Right Whale: What is the speed of electrical attraction?

laconas: I don't think anybody really knows.

It's the speed of light. Virtual photons fly around at their accustomed speed, creating the electrical field in the space around them. The speed of gravity is thought to be the same, mediated by a so-far undetected particle called the graviton.

57 posted on 01/18/2002 9:42:20 AM PST by VadeRetro
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To: VadeRetro
Virtual photons

I know what a virtual image is. I have been an optical engineer in a prior incarnation. But I do not know what a virtual photon might be.

For the speed of gravity determination they are using massive but highly sensitive devices. If something heavy moves, like a supernova, they might be able to get a measurement. I think they are waiting for a suitable event so they can get some numbers. Until then they are detecting neutrinos and doing Aetvos experiments with artificial satellites. Maybe we will be the generation that gets a clue.

58 posted on 01/18/2002 10:11:23 AM PST by RightWhale
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To: chilepepper
Heavier objects falling faster than lighter objects? I agree: if for no other reason, because the heavier object ATTRACTS the other body more, which will have a small but real velocity component up towards the falling object!

Your opinion was once universally held; but experimentation has shown that heavy and light objects fall at the same speed. Each falling object is not only attracted to the earth in proportion to its mass, but it [the falling object] also has inertia that resists the motion, so the falling object's mass cancels itself out. All that's left is the earth and the gravitational constant, which are the same for all falling objects.

59 posted on 01/18/2002 10:27:02 AM PST by PatrickHenry
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Comment #60 Removed by Moderator

To: RightWhale
I know what a virtual image is. I have been an optical engineer in a prior incarnation. But I do not know what a virtual photon might be.

In my layman's-level grasp of things (someone more qualified can always clean up my mess later on):

In the quantum scheme of things, a field is a region of space in which some property is altered. In the case of gravity, it's the geometric curvature. In the cases of electricty and magnetism, it's the permittivity and permeability, respectively.

When the object creating the fields is moved, it exchanges virtual particles--"vector bosons" of the force--with the surrounding space so the fields can change. (This gets around spooky "action at a distance" ideas of Newtonian/classical physics.) Virtual particles differ from their real cousins in that they're free. They don't really have to be accounted for in the mass/energy balance sheet of things because their energy is small and they don't exist for long. They're basically quantum hiccups.

Electric and magnetic fields are aspects of the force of electromagnetism; thus the vector boson is the photon. The presumed vector boson of the gravitational force is the graviton. Why it is presumed to propagate at photon speed, I'm not sure, but it probably has to do with relativity theory.

61 posted on 01/18/2002 10:34:14 AM PST by VadeRetro
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To: VadeRetro
Why it [the graviton] is presumed to propagate at photon speed, I'm not sure, but it probably has to do with relativity theory.

Perhaps its because the Intelligent Designer won't give him a bigger allowance. (It's a slow day.)

62 posted on 01/18/2002 10:40:23 AM PST by PatrickHenry
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To: aruanan
quantum redshift

What are we talking about here and have you any links?

63 posted on 01/18/2002 10:44:57 AM PST by Ernest_at_the_Beach
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To: chilepepper
because the heavier object ATTRACTS the other body more, which will have a small but real velocity component up towards the falling object

Yes, but you forgot it has proportionately more mass to accelerate, so it falls at the same rate.

64 posted on 01/18/2002 10:45:43 AM PST by from occupied ga
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To: Ernest_at_the_Beach
quantum redshift
What are we talking about here and have you any links?

If you do a Google search on "quantized redshift" you will be amazed.

65 posted on 01/18/2002 10:51:16 AM PST by PatrickHenry
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To: Clarity
"Chemistry for Poets"

ROFL!!

66 posted on 01/18/2002 10:53:12 AM PST by Ernest_at_the_Beach
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To: Ernest_at_the_Beach
Start here STATE OF THE UNIVERSE 2002


THE BIG BANG is dead.
It's a theory based on a theory based on an assumption made nearly 75 years ago, that THE ONLYCAUSE OF REDSHIFT IS RECESSIONAL VELOCITY. And that assumption was wrong. Observations in 1911 of intrinsic redshift in young stars crippled the recessional redshift of galaxies before it was imagined. Halton Arp's identification of physical connections between high-redshift quasars and low-redshift active galaxies in the late 60's dealt the mortal blow. The discovery of quantization of redshifts signed the death certificate.

67 posted on 01/18/2002 11:02:00 AM PST by aruanan
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To: Clarity
So here was a boundary, i.e., a minimum energy. Without another border, that doesn't sound to me like an affirmation of a necessary "discrete energy level" but rather simply a necessary minimum energy.

Oh, I see what you're driving at! OK. Deep breath. Let's see whether I can make this clear.

Imagine that you and I are standing at the end of a long hallway. I'm throwing superballs at you, and you're catching them. Whenever you catch one, you count it.

Our game is fraught with problems, however. One problem is that I throw like a girl. Sometimes I throw things straight up, and sometimes I throw things straight ahead. Another problem is that the ceiling is very sticky. Whenever a superball hits the ceiling, it gets stuck and it never makes it to you. Fortunately, you can move the ceiling up and down.

If you could see the superballs bouncing, you'd notice that they always seem to bounce to certain specific heights. But you can't see the superballs. All you know is how many I throw, how many you catch, and how high the ceiling is.

If the ceiling is too low, none of the balls make it through. That's because no matter how I through the balls, they always bounce to at least a certain height. You move the ceiling a bit higher, and still see nothing. A bit higher, still nothing, and so on, until you put the ceiling high enough to let the least-bouncy balls through.

Suddenly, you are counting a significant number of balls. "OK," you think, "since I believe the balls can have any old energy above the minimum, I expect that there will be some more balls bouncing only a little bit higher than the minimum. I'll raise the ceiling a little bit, and I'll catch a few more of the balls." So you raise the ceiling a bit, but you still see balls coming down the hallway at the same rate. So you raise it a bit more; still you get the same result. So you raise it more and more, and you realize that the rate at which balls make it down the hall has plateaued as a function of ceiling height.

Then you raise it a bit more. Suddenly, the rate of the superballs makes another big jump! This is because you're suddenly admitting the next energy level: the ceiling has been raised higher than the fixed height to which balls of this energy can bounce.

In the case of the experiment (which uses neutrons instead of superballs, a neutron absorber instead of a sticky ceiling, and a neutron detector instead of a fancy West-coast lawyer), they clearly resolve the first jump, the plateau, and the second jump. There is weak evidence for a second and a third plateau, but the finite resolution of the detector washes them out. But I'd say that they have two discrete energy levels firmly in hand.

68 posted on 01/18/2002 12:25:13 PM PST by Physicist
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To: Physicist
That's because no matter how I through the balls

"through" = throw

69 posted on 01/18/2002 12:41:39 PM PST by Physicist
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To: Physicist
Excellent !
70 posted on 01/18/2002 12:58:50 PM PST by Ernest_at_the_Beach
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To: sig226; PatrickHenry; VadeRetro; RadioAstronomer
You might be interested in #68.
71 posted on 01/18/2002 1:25:18 PM PST by Physicist
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To: Ernest_at_the_Beach
Thanks! I should have written that explanation straight away, rather than discussing the theory behind the result.
72 posted on 01/18/2002 1:26:57 PM PST by Physicist
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Comment #73 Removed by Moderator

To: Clarity
I lost track when you said they have two energy levels firmly in hand. Is one such level the "certain, minimum energy (equal to 1.41 x 10-12 electronvolts)" referred to in the article?

Yes. The bouncing neutrons can't have zero energy; there's a minimum energy they can have. You see the population of neutrons having that energy with the first jump. The subsequent plateau tells you that there are no other neutrons with a slightly higher energy.

(It's tempting to think of the plateau as representing the first energy level, but that's wrong; remember, it's a plateau in counting rate, not in energy. The first jump represents the first energy level.)

And if so, what is the second level they've found?

The sudden increase of neutrons after the first plateau represents the sudden acceptance of a second population of neutrons having a higher energy. If these neutrons had not a single energy, but a distribution of energies, you'd see the population slowly ramping up with absorber height after the first plateau, but that isn't what's seen. The counting rate jumps up sharply after the first plateau.

And then finally, when Stockholm calls you, will you get me a ticket to the ceremony?

Stockholm keeps calling me, but I won't accept the call as long as they keep reversing the charges!

74 posted on 01/18/2002 2:08:26 PM PST by Physicist
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To: longshadow
a discrete reminder...
75 posted on 01/18/2002 2:21:17 PM PST by Nebullis
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Comment #76 Removed by Moderator

To: Physicist
Stockholm keeps calling me, but I won't accept the call as long as they keep reversing the charges!

That's probably Ingrid. She's 23, single, very lonely, and she gets excited discussing cosmology. I gave her your number.

77 posted on 01/18/2002 3:01:56 PM PST by PatrickHenry
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To: Clarity
Where is that mentioned in this article?

I suppose it's not, now that I reread it. It's not the clearest piece of science journalism.

I read the paper on www.nature.com (courtesy of Penn's sitewide license). The first plateau is clearly defined on the data plot (which tells you that the jumps up to it and from it are sharp). The second plateau is more of a shoulder.

78 posted on 01/18/2002 3:31:11 PM PST by Physicist
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To: Physicist
New Scientist needs you. You're making Hazel Muir look bad here.
79 posted on 01/18/2002 5:20:44 PM PST by VadeRetro
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To: Nebullis
a discrete reminder...

How thoughtful of you to recall our discussion from many months ago.

You should also recall that I stipulated up front in that discussion that the quantum world was discrete.

80 posted on 01/18/2002 6:52:31 PM PST by longshadow
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To: longshadow
I thought the discussion was about the scope of quantum phenomena. Not whether or not quantum phenomena are discrete (after all, A=A and the Pope is Catholic).

But after looking over that thread from a year ago, I see it's just a pointless exchange of unpleasantries, not worth remembering.

81 posted on 01/20/2002 8:03:59 PM PST by Nebullis
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To: Nebullis
I thought the discussion was about the scope of quantum phenomena. Not whether or not quantum phenomena are discrete (after all, A=A and the Pope is Catholic).

As indicated below, I specifically stipulated, in my SECOND reply to you in the thread in question, the discrete nature of the quantum world, and indicated that I was referring to phenomenon in the larger world:


To: Nebullis

It is made of particles.

And those particles, do they move in discrete instantaneous JUMPS, or do they move CONTINOUSLY?

And more to the point, does the phenomona of "our world" act in instantaneous jumps, or does it act smoothly and continously? Quantum mechanics excluded; we already know and acknowledge that.

53 Posted on 01/04/2001 06:06:17 PST by longshadow
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[emphasis added]

But after looking over that thread from a year ago, I see it's just a pointless exchange of unpleasantries, not worth remembering.

Well, if you ignored my stipulation noted above, I guess it was a rather pointless exchange. As for the "unpleasantries," the record indicates that they began with your gratuitous assertion HERE:


To: longshadow

You don't know math.

99 Posted on 01/04/2001 12:34:36 PST by Nebullis
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to which I replied in kind HERE:


To: Nebullis

You don't know math.

In addition to being a fool, you are now also a liar.

100 Posted on 01/04/2001 12:37:14 PST by longshadow
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In any case, thanks for the "discrete reminder"....

82 posted on 01/21/2002 4:27:10 PM PST by longshadow
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To: longshadow
thanks for the "discrete reminder"....

You're welcome.

83 posted on 01/21/2002 4:48:08 PM PST by Nebullis
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(My husband is reading over my shoulder, wondering why I even bother with these "idiots online".)
84 posted on 01/21/2002 4:56:34 PM PST by Nebullis
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To: Ernest_at_the_Beach; Physicist
Reminds me of a "government boondagle" being funded by the National Science Foundation. It's called LIGO for Laser Interferometer Gravitational-Wave Observatory. The NSF has been funding the construction of two such observatories, one in Hanford, WA and one in Livingston, LA. CalTech and MIT are the principal investigators.

The "observatories" each consist of two 6' diameter stainless steel vacuum "beam tunnels", each 2.5 miles long and about 6 ft. in diameter, at right angles to each other.

The difference in gravitational waves in the interferometer is expected to be several orders of magnitude smaller than a human hair.

How much is this costing the taxpayers?

Looking at the web site for the NSF, it appears that spending so far is about $400 million. That's from the NSF. It is virtually impossible to find out if other government agencies are sharing the cost.

Your tax dollars at work.

85 posted on 01/21/2002 5:02:39 PM PST by jackbill
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To: jackbill
Are you saying that it's not going to work, or that you simply know better than the several panels of scientists who reviewed LIGO in detail, and concluded that it was the most important research that could be done with the money?
86 posted on 01/21/2002 6:54:05 PM PST by Physicist
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To: jackbill
Were you also in favor of killing the SSC too?
87 posted on 01/21/2002 7:01:53 PM PST by RadioAstronomer
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To: jackbill
Gravity is in many ways the least understood force. We "almost" detected gravity waves in the 1960's. The experiment has never been duplicated. One never knows what fascinating information or new technology may come from basic discoveries...
88 posted on 01/21/2002 7:24:13 PM PST by edwin hubble
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To: Ernest_at_the_Beach
The Astronomy Picture of the Day for today is on the subject of your thread.
89 posted on 01/22/2002 2:02:13 AM PST by leadpenny
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To: Physicist
Are you saying that it's not going to work

Actually, it isn't working. Someone that I know very well was just down in LA several weeks ago, helping to apply a band-aid that they hope will work. Seems that the laser is subject to interference from 60 Hz and computer fans.

90 posted on 01/22/2002 6:47:56 AM PST by jackbill
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To: RadioAstronomer
Were you also in favor of killing the SSC too?

As a matter of fact I was not a big fan of the SSC. From my understanding there were several problems, among them:

1. The cost was going through the roof and "promised" foreign financial cooperation was not forthcoming.

2. The SSC was basically duplicating the work being done by CERN in Europe.

By the way, I was working on superconductors when I retired in 1991 - among other things.

91 posted on 01/22/2002 7:02:54 AM PST by jackbill
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To: jackbill
It's called LIGO for Laser Interferometer Gravitational-Wave Observatory.

Why is this a "boondagle?"
92 posted on 01/22/2002 7:06:31 AM PST by abandon
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To: jackbill
Seems that the laser is subject to interference from 60 Hz and computer fans.

Nobody has ever built a large-scale device (particularly a first-of-its-kind device) that didn't have bugs that needed to be worked out. In my experience as an experimentalist, 98% of experimental physics consists of working out problems like that. I see no cause for hand-wringing.

93 posted on 01/22/2002 8:43:03 AM PST by Physicist
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To: jackbill
1. The cost was going through the roof

You know how that game is played. Congress is handed a schedule: this is what we're going to do, and this is how much it will cost each year. Then congress says, great, we'll give you this smaller amount. That stretches the project out and raises its cost. Congress cuts it again the next year, which raises the cost still more. This continues until congress says, look at the cost! We didn't agree to that! And they kill it.

and "promised" foreign financial cooperation was not forthcoming.

Again, that was a politically created problem having nothing to do with the machine or the physics. Japan, for example, was looking for a little cooperation from the U.S. for a project of its own (TRISTAN II/BELLE). They thought it was all worked out, one hand washing the other. Then we stiffed them and went our own way (PEP II/Babar). There are other examples, but the upshot is that our government was so uncooperative that we couldn't expect any cooperation in return.

2. The SSC was basically duplicating the work being done by CERN in Europe.

That's simply flat-out wrong. Perhaps you're thinking of the Isabelle project that was cancelled a decade or so before the SSC.

94 posted on 01/22/2002 9:00:06 AM PST by Physicist
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To: Ernest_at_the_Beach
Gravity is a push.
95 posted on 01/22/2002 9:19:25 AM PST by Orbiting_Rosie's_Head
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To: Physicist
That's simply flat-out wrong. Perhaps you're thinking of the Isabelle project that was cancelled a decade or so before the SSC.

No, I'm talking about CERN's Large Electron-Positron Collider (LEP) and its Large Hadron Collider (LHC).

96 posted on 01/22/2002 10:05:41 AM PST by jackbill
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To: jackbill
LEP is a completely different type of machine that measures totally different physics, and LHC was never intended to do general-purpose physics. Since the demise of the SSC, the LHC experiments have been re-thought in order to do general particle physics, but it still does not have the energy reach.

In 1988 I was at KEK (Kou Enerugi Butsurigaku Kenkyuujou, the National Laboratory for High Energy Physics in Japan) when Carlo Rubbia (then director of CERN) came to pitch the LHC. Of course, people were concerned that there was too much overlap with the SSC. Rubbia explained that there was very little overlap, because the LHC could not do a "minimum bias" program. This was because each interaction region would produce 5 kilowatts of pi-mesons. The packed hall gasped en masse. Everybody instantly recognized that track reconstruction was impossible in such a high-rate environment. The LHC was designed to measure one signature (the 4-muon decay of the Higgs, which would have been tough at the SSC) and to do it well.

After the SSC fell, of course, the LHC was the only game in town, and the impossible became the absolutely necessary. People started to devise ways of doing track reconstruction under such conditions. We'll see how well the schemes work (they have to work, so they will) in maybe 2008, 16 years after what should have been the completion date of the SSC.

97 posted on 01/22/2002 10:24:24 AM PST by Physicist
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To: RightWhale
What is the speed of electrical attraction?

The speed of light. It falls right out of Maxwells equations.

98 posted on 06/22/2005 2:55:16 PM PDT by El Gato
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To: Physicist
You know how that game is played. Congress is handed a schedule: this is what we're going to do, and this is how much it will cost each year. Then congress says, great, we'll give you this smaller amount. That stretches the project out and raises its cost. Congress cuts it again the next year, which raises the cost still more. This continues until congress says, look at the cost! We didn't agree to that! And they kill it.

That's the way it goes with weapons systems.

Only with highways do they not take the final step and cancel them, they just finish them at higher cost and well after the capacity is needed.

99 posted on 06/22/2005 3:00:59 PM PDT by El Gato
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To: Mind-numbed Robot
I always thought the heavier stuff ought to fall faster!

Well, at least it falls harder.


Heavier objects have more mass. Weight is the effect of gravity on a mass. Force = Mass x Acceleration. When two bodies in a vacuum of different weights are set free at the same time they accelerate downward at the same rate. Force/Mass. Or 32ft/(s squared). Hence at any point in time they have the same speed.
100 posted on 06/22/2005 3:13:47 PM PDT by GreenOgre (mohammed is the false prophet of a false god.)
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