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Spinning faster than c?


dirtyamerica
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ok, how about two 186000 mile diameter merry-go-rounds both spinning clockwise and sped up using the same technique as discussed above as fast as they will go (>.5c). I ride one on the outside, you ride the other on the outside, what do we see when we pass each other? How fast would we be going relative to each other as we passed?

 

This sounds like you are trying to slip to light speed by a technicality. My first question to you is have you read Einstein's book on relativity? Second have you taken any classes on relativity I only ask because this concept is discussed in basic physics.

 

The idea is that when you are in an inertial reference frame then you appear to be stationary to yourself. That means no acceleration so no rotation, since rotation is constant acceleration around a point. but witha large enough merry-go-round we would not perceive the rotation, just like on Earth. Anyway, in our reference frame we don't see the other MGR coming at us at c because of linear contraction and time dilation. They keep the other object below c. The important thing to remember is that in our inertial frame we think we aren't moving so to us a horse on the other MGR is traveling at a fraction of c, and to a rider on that MGR they think the same thing about us.

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I don’t think you’re including gravity in your math. Without a force to counteract centripetal force, you would then need a device that is impossibly strong. If you use gravity to counter centripetal force, then why would it matter how rigid it is?

In a vertical system gravity only helps in the top half - in the bottom half it works against [math] F_C [/math] and makes [math] F_C [/math] have to be greater.

In a horizontal system gravity does not help [math] F_C [/math] at all. You must rememeber [math] F_G [/math] would always face down, therefore only helping half the time.

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This sounds like you are trying to slip to light speed by a technicality. My first question to you is have you read Einstein's book on relativity? Second have you taken any classes on relativity I only ask because this concept is discussed in basic physics.

1) Portions, but have had many discussions on the topic. 2) Not specifically on the topic, but it was covered in one of my engineering physics courses.

 

The idea is that when you are in an inertial reference frame then you appear to be stationary to yourself. That means no acceleration so no rotation, since rotation is constant acceleration around a point. but witha large enough merry-go-round we would not perceive the rotation, just like on Earth.

Right, I did not mean to imply this by what I said at all. I am very aware that an object, in its own reference frame, has no velocity.

 

Anyway, in our reference frame we don't see the other MGR coming at us at c because of linear contraction and time dilation. They keep the other object below c.

This is partially the answer I was looking for. I was aware of time dilation and other effects of traveling at high speeds. And from my previous post, that appears to be what I was confused about. However, I am curious as to how an outer world would be perceived from this viewpoint as the velocity is not in a cartesian direction, but rather the phi cylindrical direction (which is constantly changing its cartesian direction). I suppose if you were to stare at a green ball stationary to an outside reference while you spun at very high speeds relative to that outside reference, then its color would fluctuate between all the colors. Also, I suppose time would pass slower for you half the time and slower for the ball the other half of the time.

 

Hmm... I guess it all ends up that you can represent any instant "cartesianly" anyway, so I'll just sheepishly go away and end this self-flagellation.

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This is partially the answer I was looking for. I was aware of time dilation and other effects of traveling at high speeds. And from my previous post' date=' that appears to be what I was confused about. However, I am curious as to how an outer world would be perceived from this viewpoint as the velocity is not in a cartesian direction, but rather the phi cylindrical direction (which is constantly changing its cartesian direction). I suppose if you were to stare at a green ball stationary to an outside reference while you spun at very high speeds relative to that outside reference, then its color would fluctuate between all the colors. Also, I suppose time would pass slower for you half the time and slower for the ball the other half of the time.

 

Hmm... I guess it all ends up that you can represent any instant "cartesianly" anyway, so I'll just sheepishly go away and end this self-flagellation.[/quote']

 

you can establish a reference frame on a the MGR all we have to do is set up a noninertial refernce frame. This may seem odd but when we establish the reference frame we would add some fictitious forces. An example of this is the coreolis force on earth. For those with some physics or math background there is a section in the book Analytical Mechanics by Fowles and Cassiday.

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OK, I've read the responses including the other thread that relates to this concept. So what if we forget about an outside observer off the wheel and it's just you and flashlight on the edge of the wheel, spinning at c. Isn't there an absolute speed of light regardless of the velocity of the emitting object? I'm having a hard time explaining my point here.(?)

 

And also what if the wheel was made out of a neutron or some object bound together by one of the nuclear forces...wouldn't it be able to withstand the forces of gravity or is the amount of centrifugal force brought on from the mass too much to handle? What about an object like a black hole...it's gravity is such a strong force of gravity...would this be enough to hold a wheel together if it were interwoven with a black hole?

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