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40 votes
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Why didn't Michelson and Morley assume or conclude that aether is homogenous and permeate all of space?

why didn't they assumed or concluded that ether is homogeneous and permeate all of space That was the initial assumption. instead of coming from an unspecified source or direction dubbed the ether ...
BowlOfRed's user avatar
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21 votes
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Observation of the effect of gravity on the motion of antimatter

Usually these error estimates are "one sigma" error bars, which is roughly the same thing as a 68% confidence limit. If you have an ensemble of data with $1\sigma$ error bars, you expect ...
rob's user avatar
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19 votes

How much power does it take to maintain the high vacuums in advanced physics experiments?

As someone who has worked on an experiment with an ultra-high vacuum, I can tell you an order of magnitude. However, the real answer is that asking how much power it takes isn't really the right way ...
AXensen's user avatar
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17 votes
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Foucault's measurements of the speed of light

Foucault published the results of his rotating mirror experiments in Comptes rendus hebdomadaires des séances de l'Académie des sciences, Compt. Rend. 55, 792 (1862). Foucault's account of the ...
Farcher's user avatar
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17 votes

How do we know what physics or science textbook said is correct?

Strictly speaking, you don't. All science is tentative and subject to change should new evidence or new insights arise. All conclusions are not only open to challenge, but it is part of the process ...
Nullius in Verba's user avatar
16 votes
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What are the experimental difficulties in measuring the Unruh effect?

Detected Hawking–Unruh thermal bath temperature and acceleration needed for a detector to achieve registration of that vacuum temperature near detector surroundings and Unruh radiation, if any, is ...
Agnius Vasiliauskas's user avatar
16 votes

How do we know what physics or science textbook said is correct?

Where possible, you should check the claims of textbooks for yourself. It is certainly possible to reproduce experiments carried out by Galileo, Leonardo, Newton, Faraday and so on, with the added ...
gandalf61's user avatar
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13 votes
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What is the control group in neutrino detection?

Short answer - one can detect what direction neutrinos come from. Neutrino detectors don't just count neutrino collisions. Neutrinos either hit something in the detector or they themselves are ...
AXensen's user avatar
  • 7,367
12 votes

The physics behind a homemade particle accelerator

Yes, in this video the centripetal acceleration is provided by the tube. This is kind of overcomplicated language for "the tube is the only reason the ball follows a circular path." The ...
AXensen's user avatar
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12 votes
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Why has it been so hard to come up with testable predictions for string theory?

One problem is that the Standard Model is too good in the sense that the predictions it makes are expected to work to almost perfect precision for many magnitudes of energy above anything we can ...
Thomas Tappeiner's user avatar
12 votes

Breaking the rock using eggs

If water can create the Grand Canyon and the Dakota Badlands, then with enough eggs and time you can certainly break a rock. Just throw eggs at the rock continuously for a million years or so.
gandalf61's user avatar
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11 votes
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How can it be "unfortunate" while this is what the experiments want?

This is "unfortunate" because if you want to use a particle accelerator to probe deeper laws of nature, it needs to accelerate particles to as high energy as possible, not just "any ...
AXensen's user avatar
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9 votes

What are the experimental difficulties in measuring the Unruh effect?

The conditions to measure the Unruh effect/ Unruh radiation are very difficult to produce with our current experimental capabilities. We need a relativistic accelerating frame to produce this ...
FearlessVirgo's user avatar
9 votes

How can it be "unfortunate" while this is what the experiments want?

Your difficulty is about English, not physics. The references to 'this' unfortunate thing and the thing 'which' experimenters want do not point to the same item. Perhaps the author condensed their ...
ariola's user avatar
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9 votes
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What evidence do we have for GR in the nonlinear regime?

The evidence is the observed perihelion precession of Mercury. This cannot be explained by linearized GR (or by Newtonian gravity), but it is explained by the leading non-linear effect of GR: in ...
Avantgarde's user avatar
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8 votes

Why has it been so hard to come up with testable predictions for string theory?

To put it more simply: The characteristic energy scales at which string theory is dominant are so incredibly high as to require particle accelerators that would need to be ~light-years in length to ...
niels nielsen's user avatar
8 votes
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Getting the spectrum of light source at high intensity (for low transmittance measurement)

Many spectrometers can change measurement time. Sometimes labeled as "integration time". So, suppose you set light at minimum intensity suitable for measurement without sample. Then increase ...
Zizy Archer's user avatar
7 votes
Accepted

Does the EMF of a battery change with time?

is that a result of a decrease in the EMF of a cell or an increase in the internal resistance of the cell of both? It's both. Batteries are surprisingly simple things, at least in principle. A ...
John Rennie's user avatar
7 votes

Why has it been so hard to come up with testable predictions for string theory?

Here is my take on your question. I might come back to it when I have more time hence the square brackets at the end. I address the answer at the level of an enthusiast who is not technically minded, ...
SvenForkbeard's user avatar
7 votes

When was it possible to observe the special-relativistic modification of Energy?

I think that the point where technology reached the relativistic realm was when the first cyclotrons started to accelerate particles to relativistic velocities. The very first cyclotron was a tabletop ...
Cleonis's user avatar
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7 votes
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Explaining deviations in simulated to experimental Cs-137 spectrum

Backscattered photons can Compton scatter again, so the rise below the backscatter peak is likely the Compton edge of the backscatter peak. This feature due to multiple Compton scattering is ...
David Bailey's user avatar
  • 11.3k
7 votes

Getting the spectrum of light source at high intensity (for low transmittance measurement)

I think you are on the right track. What I did in a similar situation was to use some filter with a known attenuation. In my experiment I used glass plates with a finely ground surface. This should ...
John Rennie's user avatar
6 votes
Accepted

DIY Spectrophotometer doesn't work properly in the IR range

I did some more testing, and figured out that 940nm was simply out of the range of my spectrophotometer. Looking at the scale in the software after calibration, it should work fine for wavelengths up ...
Matthew_R's user avatar
  • 321
6 votes

Specific experiments that affirm particle-in-a-box QM theory

Search for papers/ videos on GaAs/AlGaAs heterostructures. It is possible to construct quantum wells by combining certain types of semiconductors with different band gaps. For example, you can build a ...
driver99's user avatar
6 votes
Accepted

How is parity of the deuteron measured experimentally?

Before quarks were discovered, the intrinsic parities of the proton and neutron were positive by convention. After quarks were discovered, the intrinsic parity of hadrons could be derived from their ...
David Bailey's user avatar
  • 11.3k
6 votes

How do we know what physics or science textbook said is correct?

To give you a satisfactory answer to your question would take a book -- or perhaps a six-part series from 1987 on PBS. And you are in luck, it's free on YouTube: The Ring of Truth: How We Know What We ...
MTA's user avatar
  • 199
6 votes

Calculating average from several independent physical experiments

First -- do the voltmeters really only give you 2 significant figures? If so, you shouldn't report the final results to more than 2 sig figs, and to do this analysis carefully you should account for ...
Andrew's user avatar
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6 votes
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Are Weinberg's soft theorems relevant when making predictions about collider physics?

Gravitons have never been observed, much less graviton scattering, so the graviton soft theorem is not relevant for particle physics experiments. The graviton soft theorem has been shown to be related ...
Andrew's user avatar
  • 48.8k
5 votes

Had a real experiment ever been done to demonstrate and calculate the magnetic field of a rotating charged disk? Or only thought experiments?

See Rowland, "On The Magnetic Effect of Electric Convection", American Journal of Science s3-15, 30-38 (1878). The whole article is paywalled (though given its date it should actually be in ...
Michael Seifert's user avatar
5 votes

Does the EMF of a battery change with time?

Usually, it's both EMF and (non-ohmic) resistance that change. Temperature and aging also change these. Cold cells generally have higher EMF and resistance. Old cells generally have lower EMF and ...
John Doty's user avatar
  • 21k

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