A graviton by any other name...

[rrw4rusty]

Hi,

 

Three questions:

 

1. Can a person in a sound proof air tight room with no windows tell the difference between 1 gee produced because:

 

a. the room is on Earth

b. the room is under constant acceleration

c. the room is being subjected to centrifugal force?

 

2. Aren't all three due to bending space/time?

 

3. Aren't gravitons involved in all of the above?

 

From the armchair,

Rusty

[swansont]

Hi,

 

Three questions:

 

1. Can a person in a sound proof air tight room with no windows tell the difference between 1 gee produced because:

 

a. the room is on Earth

b. the room is under constant acceleration

c. the room is being subjected to centrifugal force?

 

2. Aren't all three due to bending space/time?

 

3. Aren't gravitons involved in all of the above?

 

From the armchair,

Rusty

 

1. The equivalence principle tells you that you can't tell the difference between acceleration and standing in a uniform gravitational field.

 

2. You can view it that way; none of those are inertial frames, so you can either change your geometry to explain the effects or you invent pseudoforces (like we often do with centrifugal force) to make it seem like we are in an inertial frame.

 

3. No. Gravitons are the proposed exchange particle used in quantum theories of gravity, but relativity is a classical theory. You use one explanation or the other, not both at the same time.

[Moontanman]

Hi,

 

Three questions:

 

1. Can a person in a sound proof air tight room with no windows tell the difference between 1 gee produced because:

 

a. the room is on Earth

b. the room is under constant acceleration

 

I'm thinking about it.

 

c. the room is being subjected to centrifugal force?

 

A coin will not spin when you are undergoing centrifugal force.

 

2. Aren't all three due to bending space/time?

 

NO

 

3. Aren't gravitons involved in all of the above?

 

No

[Severian]

A coin will not spin when you are undergoing centrifugal force.

 

That is an interesting statement. Al coins on Earth feel a centrifugal force from the Earth's rotation. Does that mean they can't spin?

 

...just a sec...

 

...just tried it, and they do spin, so you must be wrong.

 

(Isn't observational science wonderful?)

[rrw4rusty]

That is an interesting statement. Al coins on Earth feel a centrifugal force from the Earth's rotation. Does that mean they can't spin?

 

...just a sec...

 

...just tried it, and they do spin, so you must be wrong.

 

(Isn't observational science wonderful?)

 

Oh, that's because Earth's gravity over powers the centrifugal force. The trick is to tweak the balance -- since you can't change the Earth's gravity you have to put on more spin and increase the centrifugal force. I use a cutting board -- cutting board and coin in hand, begin running really fast (make sure you're pointed due East) and try spinning the coin on the cutting board. If it continues to spin, just run a little faster and eventually the coin will fail to spin.

 

Keep us posted.

 

Rusty

[Bob_for_short]

Hi,

 

Three questions:

 

1. Can a person in a sound proof air tight room with no windows tell the difference between 1 gee produced because...

 

In the inertial reference frame where there is no acceleration a charged particle or dipole will not radiate. Falling down or rotating will cause EM radiation.

[moth]

cutting board and coin in hand, begin running really fast (make sure you're pointed due East) and try spinning the coin on the cutting board. If it continues to spin, just run a little faster and eventually the coin will fail to spin.Rusty

 

or you could use a foucault pendulum to show the earth's rotation.

[rrw4rusty]

In the inertial reference frame where there is no acceleration a charged particle or dipole will not radiate. Falling down or rotating will cause EM radiation.

 

Interesting. What I really wanted to know was is there any reason rotation won't work in space as a replacement for gravity. Same for acceleration. I'd heard that NASA had canned the idea of centrifugal force in future space ships. I should have just asked that question, Dho!

 

Rusty

[Spyman]

What I really wanted to know was is there any reason rotation won't work in space as a replacement for gravity. Same for acceleration.

Here is a Link you might find interesting to read then:

 

"Artificial gravity is a simulation of gravity in outer space or free-fall. Artificial gravity is desirable for long-term space travel or habitation, for ease of mobility and to avoid the adverse health effects of weightlessness."

 

"The engineering challenges of creating a rotating spacecraft are comparatively modest to any other proposed approach. Theoretical spacecraft designs using artificial gravity have a great number of variants with intrinsic problems and advantages. To reduce Coriolis forces to livable levels, a rate of spin of 2 rpm or less would be needed. To produce 1g, the radius of rotation would have to be 224 m (735 ft) or greater, which would make for a very large spaceship."

http://en.wikipedia.org/wiki/Artificial_gravity