Science question

General discussions of interest to readers and fans of Harlan Ellison.

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DVG
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Science question

Postby DVG » Thu Oct 16, 2008 3:43 pm

Imagine a room at standard earth gravity. In the center of the room there is a table with a large clock on it.

Through some mechanism, the gravity of the room is reduced to zero-g.

Assuming there has been no shifting of the room itself, no air current within or other independent force involved, will the table and the clock begin to float in the room or will they stay at rest in their original configuration?

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Re: Science question

Postby Moderator » Thu Oct 16, 2008 3:56 pm

DVG wrote:Imagine a room at standard earth gravity. In the center of the room there is a table with a large clock on it.

Through some mechanism, the gravity of the room is reduced to zero-g.

Assuming there has been no shifting of the room itself, no air current within or other independent force involved, will the table and the clock begin to float in the room or will they stay at rest in their original configuration?


If no outside force works on the clock or table, it will not move. (Outside force also including planetary spin, brownian motion, external gravitational influences -- Moon, etc, -- and earthquakes.)



(On the other hand, you will be able to hear someone scream.)
- I love to find adventure. All I need is a change of clothes, my Nikon, an open mind and a strong cup of coffee.

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Postby Moderator » Thu Oct 16, 2008 3:58 pm

Welcome back, by the way. :wink:
- I love to find adventure. All I need is a change of clothes, my Nikon, an open mind and a strong cup of coffee.

DVG
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Postby DVG » Thu Oct 16, 2008 4:02 pm

Thanks--

My question is based on a comment in Peter Nichols wonderful book “The Science in Science Fiction.” In criticizing a scenario where antigravity is featured, Nichols reprints an image from a film where a young boy is floating while scientists look on and asks: “if there is no gravity in the room why are objects resting on the desk?” My thought is that if no one moves the objects, they would remain on the desk exactly as before (re Newton).

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robochrist
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Postby robochrist » Thu Oct 16, 2008 7:38 pm

Putting it another way, "all things being equal".

Everything remains at rest unless acted upon by an unbalanced external force.

If it were otherwise, everything ELSE would be a floatin', not just the clock and table.

Now let's see you ask a guy with hypoglycemia if that law has any meaning to HIM!!!

WEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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Steve Evil
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Postby Steve Evil » Thu Oct 16, 2008 8:22 pm

Do you mean if the gravity starts normal and is slowly reduced to zero?

cynic
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Re: Science question

Postby cynic » Thu Oct 16, 2008 9:58 pm

DVG wrote:Imagine a room at standard earth gravity. In the center of the room there is a table with a large clock on it.

Through some mechanism, the gravity of the room is reduced to zero-g.

Assuming there has been no shifting of the room itself, no air current within or other independent force involved, will the table and the clock begin to float in the room or will they stay at rest in their original configuration?


a mechanical clock,spring,pendulum,even digital quartz DEPEND on internal motion to operate.the clock MUST move,no longer bound by gravity or friction with the table.

but let's dicount even internal "mechanical"motion and inherant brownian motion.

an hour glass on a table,zero grav ensues,the sand stops.

but the moment before,the table top was actually minutely distorted(bowed) by the weight of the glass.

remove gravity,the table "springs" back into a"relaxed"state and sends the glass, what was, up.(in that moment of acceleration some sand flows)

the motion of the table top(still having mass)would cause it to jump off the floor(as well as push the room"down"minutely)

even with a bare table,the legs are microscopicaly compressed,and on removal of weight,they would elongate,sending the table what was "up"

i think this my be what evil steve was getting at,but the results would be similar(less pronounced).

either that,or i have no efin ideer

cluelessly yours,mike

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robochrist
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Postby robochrist » Fri Oct 17, 2008 12:49 am

Look: you only have 3 laws to GO with!

It's not THAT hard to figure out.

You're right: it shouldn't make any difference. The objects would have the same inertia.

TRUST me. It's the graphic artist's job to KNOW this stuff.

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Duane
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Postby Duane » Fri Oct 17, 2008 11:29 am

This one will REALLY blow your mind:

It is possible to invent a clock that is TOO precise.

I remember a SciAm article a while back that talked about atomic clocks, and how they can be made more precise than they currently are (and they are SCARY precise now!).

Imagine this scenario:

You have two identical clocks sitting side by side on a shelf. You pick one up and move it to an upper shelf a few feet above the original one. UH-OH!!

If the clocks are too precise, the one that was moved will no longer be in sync with the stationary one: The acceleration involved in moving the clock will cause a tiny, tiny time dilation into the mechanism, and the two clocks will no longer be in sync. Not only that, since gravity can affect the passage of time (in a relativistic sense), since the upper clock sits farther up Earth's gravity well than the stationary one, the length of its second will be increased by something like one trillion trillionth of a percent. If the two clocks are precise enough to measure these changes, one cannot sync them up ever again without restarting them.

Never should have earned that Math/Physics double major. It's been nothing but trouble ever since.

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robochrist
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Postby robochrist » Fri Oct 17, 2008 1:52 pm

Duane -

Maybe you should have worked for NASA in 2003 when engineers insisted that foam particles - regardless of their acceleration - could NOT damage a shuttle wing and cause a crash.

They never bothered doing the math, falling back on the layman's tool, intuition.

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Postby cynic » Fri Oct 17, 2008 1:54 pm

DUANE,

fibber!you well know "too precise "is an oxymoron...?non sequitur...?

SOMETHIN' LIKE THAT (ralph cramden)

my math sucks,never got past pythagorus or dimensional analysis

but someday...

correct, expand or alter if you will ,my (incomplete,initial)appraisal of DVGs scenario

70'71'triumph,mike

p.s.my bro. steve offered sci am is a few years behind,try "physics today"? next time i see him i'll give him dvgs posit

THANKS DVG

cynic
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Postby cynic » Fri Oct 17, 2008 2:19 pm

robochrist wrote:
They never bothered doing the math, falling back on the layman's tool, intuition.


sometimes all we have to go by is intuition

you're a good guy,

and i thought I was the

cynic

luv ya man

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Duane
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Postby Duane » Sun Oct 19, 2008 11:31 am

Should have pursued that minor in English....

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Postby cynic » Sun Oct 19, 2008 12:20 pm

Duane wrote:Should have pursued that minor in English....


whyforsir?

not that it would be a bad thing, or any of my darn buisness.

mike


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