# Tag Info

### Does gravitation really exist at the particle level?

For the interaction of one small (atom scale) mass and one large mass, measurements of the Earth's atmosphere that anyone could do with a homemade barometer and a nearby mountain constitute direct ...
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### Does gravitation really exist at the particle level?

Here is an easy way to grasp how difficult it would be to make the direct measurement you propose. Take two protons and place them one centimeter apart. They will exert a certain tiny amount of ...
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### Does gravitation really exist at the particle level?

FWIW, small particles react to the big ones:Experiments have been done with neutrons in a gravity field. The phase of their wavefunction was shifted, as was shown by interference. If the neutron didn'...
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### Can this experiment successfully be used to find out one-way speed of light?

No. "identical apparatus which can shoot a ball at the same speed [in opposite directions]" The same what now? The same speed in two directions? Sure, the apparatus looks like it works the ...
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### Can this experiment successfully be used to find out one-way speed of light?

Edited to add: The first four paragraphs below constitute my original answer. Below that is a new and better answer. Original Answer: Suppose the distance from A to C (and from B to C) is $s$. ...
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Accepted

### Experiments check out theories but who or what checks out the experiments?

When I started with particle physics experiments back in the '70's, there was a large number of independent experiments gathering data and slowly building up what is now the mainstream standard model. ...
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### Experiments check out theories but who or what checks out the experiments?

Other experimentalists. Independent replication of results is important. Incremental advancements in the accuracy or refinement of the statistics by having more data. Refinement of theories as more ...
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### Has the Michelson-Morley experiment been done in space?

I mean that exact experiment Well, ”exact” is a little excessive. The exact experimental apparatus is on the ground at Case Western Reserve University, and nobody will be burning an argand lamp in ...
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### Has there been any experiment trying to measure the Ricci Curvature of the universe?

Simple Answer: The Friedmann Equations comes from the EFE (Einstein Field Equations) $$G_{\mu\nu} = \kappa T_{\mu \nu}$$ $$R_{\mu \nu} - \frac{1}{2}g_{\mu\nu}R= \kappa T_{\mu \nu}$$ Thus, when you ...
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### Experiments check out theories but who or what checks out the experiments?

Replicating experiments checks for human, equipment and random errors. These errors, I believe, are by far the most frequent ones, so it is always necessary to replicate experiments. If experiment is ...
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Accepted

### How Chadwick concluded that the particles are neutrons but not photons?

The WP article I linked summarizes that In 1931, Walther Bothe and Herbert Becker found that if alpha particle radiation from polonium fell on beryllium, boron, or lithium, an unusually penetrating ...
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Accepted

### Subtracting background from a radioactive measurement

If the background was constant in time, then measuring it twice before or twice after or once before and once after would all provide equivalent information. The problem is that you cannot be sure ...
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1 vote

### Does gravitation really exist at the particle level?

That's exactly what we are observing when we look at the night sky and see galaxies form out of nothing but dust. Ever wondered why we are here to ask this question? Because gravity pulled together ...
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1 vote

### If I was to take light and loop it between two iron cores, like a transformer with copper; what would happen?

Nothing would happen. You would need a fiber optic cable, no light gets out, the iron core does nothing to the light, so your second fiber optic (with more or less loops) would not have any light in ...
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1 vote
Accepted

### Running of the fine structure constant: meaning of $\alpha(Q^2=0)$?

As I discuss also in this answer of mine, there is no unique definition of "the energy scale of a process", i.e. the $Q^2$, and hence there is also not a single function $\alpha(Q^2)$ - ...
• 105k
1 vote
Accepted

### Pile-up events in collider experiments and the average number of interactions

Yes. Pile-up is when two or more events happen "at the same time" in a detector, where the exact definition of "at the same time" will depend on your detector and your particular ...
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