# Questions tagged [experimental-physics]

For questions about design, process, data, or analysis of experiments and observations.

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### What evidence do we have for GR in the nonlinear regime?

The classical equations for Einstein's GR (modulo the cosmological constant) read $$R_{\mu\nu} - \frac{1}{2} R g_{\mu\nu} = \kappa T_{\mu\nu}.$$ These equations have a complicated linearization that ...
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### How does MEMS low insertion loss fiber optic switch work? [closed]

I'm currently looking for a low insertion loss fiber optic switch to be able to change the light source of a spectrometer. Since this will be used in harsh conditions, I was hoping to find one with no ...
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### Why were multiple layers of absorbers and scintillators used in the CMS HCAL?

Why were multiple layers of absorbers and scintillators used in the CMS HCAL? Couldn't they have used just one absorber and one scintillator layer? Why was the choice made to have multiple layers?
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### Suspiciously wrong value by factor of $1/2$ in experiment to calculate frequency of AC mains using sonometer

In school we performed the following experiment: We use a step down transformer ($220V$ to $6V$) and pass current through a "sonometer wire". We have a meter scale underneath the wire. ...
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### Foucault's measurements of the speed of light

I understand that you can — in principle — measure the speed of light with the rotating mirror experiment. What I don't understand: How can you accurately measure (or fix) the number of rotations of ...
637 views

### Half wave plate + polarizer vs rotatable polarizer + fixed polarizer

I am learning about optical setups and am looking at how the intensity of the laser beam is attenuated for use. A lab in my institute uses a rotatable Half Wave plate and a polarizer fixed at the ...
140 views

### What is the actual version (using electrons) of this quantum thought-experiment from an MIT lecture?

In the first lecture of the MIT quantum-mechanics 2013 course, the professor develops basic abstract concepts, by inventing hypothetical binary measurable properties of electrons (hardness (H)= hard ...
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### What's the theoretical max output of the National Ignition Facility (NIF)?

With the latest Ignition event at the National Ignition Facility (NIF) producing 3.5Mj of energy, I'm curious to know. Using the pellets that they are, what's the maximum energy they could produce, ...
227 views

### How to measure the tension in a guitar string without directly measuring the frequency of the sound?

I'm looking for an accurate method to measure the tension in a guitar string, without using a sonometer setup nor by measuring the frequency. the current method that I have in mind is to measure the ...
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### Specific experiments that affirm particle-in-a-box QM theory

The infinite square well (and variations) are some of the best-studied systems in quantum mechanics and are often used as the starting point for any quantum mechanical education, as the Schrodinger ...
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### Has Quantum Spin of a Single Particle Been Measured Twice Experimentally?

In quantum mechanics, the concept of spin is fascinating. My question revolves around the experimental aspect of this phenomenon. Specifically, I'm curious to know if we have ever measured the quantum ...
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### What are the two basic experiments to identify different phases in high $T_c$ cuprates systems?

what are the two basic experiments to identify different phases like antiferromagnetic, pseudogap, superconducting, strange metal and fermi-liquid in high $T_c$ cuprates systems like BSCCO and YBCO?
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### SLM pulse shaping to delay (and advance) ultrashort pulses in time

I am trying to replicate some of the experiments discussed in this excellent publication: SLM for pulse shaping In particular, I replicated the setup configuration in Figure 14 and I want to use the ...
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### How we know that Dirac equation in curved spacetime is the correct one?

Dirac equation in curved spacetime is given by $$\left(i \gamma^\mu D_\mu-m\right) \Psi=0$$ How does we know that this is the correct equations to describe spinors in curved space time? Is there any ...
1 vote
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### Is there an intuitional way to tell which physical quantities are angular frequency and which are frequency?

Such as the natural linewidth is defined to be angular frequency, while the absolute frequency of laser is frequency. By far I haven't found a good way not to learn it by roting. Would anyone be ...
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### Probability distributions of bounded measurement results?

Say that I am measuring a length very inaccurately. For instance, I might measure $1m$ with an uncertainty of $50cm$. If I model the probability distribution as a Gaussian with $\sigma=50cm$, I run ...
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### Up-to-date values of Yukawa couplings (2023)

Where can I find the most recent values for the Yukawa couplings in 2023? I currently have access to the values from 2011, but I guess precision has improved over the last decade in measurements. Edit:...
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### Cloud Chamber Help Needed! [closed]

I was inspired by this video to attempt to create a cloud chamber without dry ice (it's very challenging to get where I live) and I have had limited success so far. This is what the design looks like: ...
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### What happens when screen is not placed where Image is focused but elsewhere?

When we try to form a real image on a screen by a convex lens, we place the screen at a distance where the image is focused. But if we try to place the screen at a distance less than the distance ...
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### Can we design an experiment or an intuitive way to demonstrate tidal locking?

I was explaining the tidal locking phenomenon to a friend. First I started with the formation of solar system and how at the beginning the planets were actually like balls of magma-esque rocks. And ...
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### How do we measure the probability of outcomes in a quantum computer if qubits collapse when measured?

I understand the idea behind Quantum Computing being that we superpose all possible states of a system of qubits and amplify the probabilities of whatever it is that we want depending on the circuit ...
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### Does the EMF of a battery change with time?

OK, so... I know that batteries provide less and less energy with time. My question is- is that a result of a decrease in the EMF of a cell or an increase in the internal resistance of the cell or ...
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### Are non-virtual particles of QFT real?

Perhaps the question may seem a bit provocative, but it refers to several mathematical and, presently physical facts, pointed out a long time ago: The Unruh effect suggests that an accelerated ...
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### What are the physical concepts that can be associated with the operation of a hydraulic arm? [closed]

I am developing a project that requires an explanation of the physical concepts behind something applicable, like in the industry. I have chosen to describe the concepts behind the operation of a ...
66 views

### Anisotropic Behavior of Glass in the Faraday Effect Experiment

I'm currently working on an experiment that uses the Faraday effect to determine the Verdet constant of SF-57 glass. Basically, similar to the photo above, I have a LED that generates a 405nm light. ...
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### How can i find the value of Planck's constant using Black body radiation?

I'm working for a physics project for Highschool, and i'm currently thinking about using black body radiation to measure Planck's constant. I know there is an option using the photoelectric effect but ...
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### What are the experimental difficulties in measuring the Unruh effect?

The Unruh effect was predicted in 1976. As someone with no background in experimental physics I find it surprising this effect hasn't been measured yet. What are the experimental difficulties (and ...
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### Are there enough parameters in standard model to falsify SUSY?

I know that the search for Higgs would be quite pointless if there was no estimation of its mass. Namely the perturbative violation of unitatity, gave us an upper bound on its mass.Unitarity ...
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### Millikan's oil drop experiment [duplicate]

In Millikan's oil drop experiment why oil drop only pick negative charge from gas between both charged plates? Why not oil drop pick positive charge?
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### About the experiment for pressure in solids in thermodynamic

I want to understand something: when someone measure the pressure, temperature and specific volume of a material, I think the pressure is applied in all directions of the material. This can be ...
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### Had a real experiment ever been done to demonstrate and calculate the magnetic field of a rotating charged disk? Or only thought experiments?

I have been trying to find if a real experiment has ever been done to prove and calculate the magnetic field of a rotating charged disk, whether it's a conducting or a non-conducting charged disk. All ...
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### How efficient are coincidence counting techniques?

Obviously there is a limitation as to how well experimental configurations that depend on coincidence counting can efficiently remove the noise present at any given experiment. This leads me to ...
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### Why is a large magnetic field problematic (for topological physics)?

In papers studying or searching for topological order (intrinsic or symmetry-protected) in various condensed matter systems (e.g. Field-tuned and zero-field fractional Chern insulators in magic angle ...
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Professor Brian Greene covers a unique angle into the twin paradox by having the stationary observer and the rocket release light beams towards each other in fixed intervals according to their proper ...
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### Are there references of influences on physical processes in experiments?

Suppose I have some physical process to use in some experiment. For instance, let's consider just looking at an object to measure its position. The basic modelization for this is to consider geometric ...
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### What is vetoing in the context of experimental particle physics?

I saw in this paper by the CMS Collaboration that two of the selection requirements defining the signal regions are the requirements on $b$ jet veto and $\tau_h$ veto. What is, in this context, a veto ...
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