Measure the speed of earth in universe

AI Thread Summary
The discussion centers on measuring Earth's speed through the universe using an electrostatic sphere and a sensitive magnetometer in a screened magnetic field. It is established that all motion is relative, and past experiments, such as the Michelson-Morley experiment, found no absolute velocity, leading to the development of special relativity. While Earth's speed relative to the Cosmic Microwave Background (CMB) is approximately 370 km/s towards Leo, its practical significance is questioned. Participants agree that despite being a measurable fact, it lacks meaningful consequences in a broader context. The consensus is that absolute speed in the universe remains an elusive concept.
snofox
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suppose an electrostatic sphere and an very sensitive magnetometer are placed in a space that has magnetic field outside been screened ideally. Can we know the speed of the Earth transverse in the universe by dealing with the data obtained?
 
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I thought it was established that there is no real meaning to 'speed in the universe'. All motion is relative. Michleson and Morley (1887) did a famous experiment to determine our speed through the 'aether' and detected nothing. Afaik, no one has proved otherwise.
 
It is already known that we are moving with respect to the CMB, which is about as close as one could reasonably get to any definition of "speed in the universe", and that speed is pretty well known. In any event it is of no consequence that I am aware of.
 
Which direction?
 
370km/s in the direction of Leo, apparently, is what the doppler shift indicates. But what does that actually mean? See this link from some while ago, on PF.
 
snofox said:
suppose an electrostatic sphere and an very sensitive magnetometer are placed in a space that has magnetic field outside been screened ideally. Can we know the speed of the Earth transverse in the universe by dealing with the data obtained?

Hi welcome to physicsforums! :smile:

Such experiments were done in the late 19the century and no effect was found at all. That led to the conclusion that the relativity principle must also be valid for electromagnetic effects - thus no "absolute velocity" can be measured. And from that emerged the Lorentz transformations and special relativity.
 
sophiecentaur said:
370km/s in the direction of Leo, apparently, is what the doppler shift indicates. But what does that actually mean? See this link from some while ago, on PF.

As I said, I don't think it has any significance. I mean, it is a physical fact, but it has no practical consequences.
 
Last edited:
phinds said:
As I said, I don't thing it has any significance. I mean, it is a physical fact, but it has no practical consequences.
I agree.
 

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