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

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14
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3answers
1k views

What is the most compelling evidence of General Relativity in the presence of matter and energy?

The most oft-cited triumphs of GR are things such as the shifting perihelion of Mercury, gravitational redshift experiments, and gravitational lensing. But, as far as I know, these are only ...
6
votes
7answers
3k views

Is there any reproducible tested evidence for Ni-H cold fusion?

The main replications of cold fusion, the ones that are beyond reproach, used Pd/d as the system. But commercial developers have often claim to use Ni-H to achieve similar effects. The claims include ...
17
votes
6answers
3k views

Why should any physicist know, to some degree, experimental physics?

I've been trying to design a list with reasons why a proper theoretical physicist should understand the methods and the difficulty of doing experimental physics. So far I've only thought of two ...
13
votes
4answers
963 views

The maximum distance for which Coulomb's law has been verified?

We know that Coulomb's law, $F_{12} = \frac{kq_1q_2}{r^2}$, was experimentally verified for small distances by Coulomb himself at the and of the XVIII century. The question is what is the maximum ...
11
votes
3answers
346 views

Can someone clarify whether the recent experiment closing all remaining loopholes to Bell's Theorem really shut the door on local realism for good?

I saw this recent article on Phys.org that purports to close all remaining loopholes that previous experiments on violations of Bell's inequality left open. My question is, does this really close the ...
11
votes
1answer
613 views

The status of the BICEP2 'discovery' after Planck 2014

The tumultous period after the original announcement that the BICEP2 experiment had supposedly detected strong evidence of cosmological inflation in the form of B-mode polarization in the cosmic ...
10
votes
3answers
927 views

How hot is the water in the pot?

Question: How hot is the water in the pot? More precisely speaking, how can I get a temperature of the water as a function of time a priori? Background & My attempt: Recently I started spend ...
8
votes
3answers
1k views

Why is there a hiss sound when water falls on a hot surface?

Why is there a hiss sound when water falls on a hot surface? I have searched a lot, asked my teachers but none of them seem to give me the logical answer to it.
5
votes
2answers
1k views

How is angular momentum measured in experiments/in practice? [duplicate]

Possible Duplicate: How does one experimentally determine chirality, helicity and spin? How do you find spin of a particle from experimental data? We read about and study angular momentum ...
3
votes
4answers
672 views

Is the principle of Conservation of Energy empirically verifiable?

Before I am inundated by myriad and vociferous claims that conservation of energy is the single most well-attested and experimentally verified principle in all of science, let me say that I am well ...
16
votes
5answers
1k views

Does a magnetically suspended frog feel weightless?

Magnetic levitation has been used to suspend frogs in midair. I was wondering: Does the animal still feel gravitational pull? I mean: Does the frog feel like an astronaut on the ISS, or does he feel ...
15
votes
1answer
411 views

Does my green laser pointer emit three distinct frequencies, or is my measurement flawed?

I was playing around with a cheap diffraction grating and my set of laser pointers, and I noticed that while the red and the blue pointers produce a single point in the spectrum, my green laser ...
15
votes
9answers
2k views

What are good mechanics experiments for 10 year olds? [closed]

I'm trying to explain elementary mechanics - without the benefits of calculus or even algebra - and struggling. I'd like to find reasonable ways to demonstrate Newton's laws, minimally, and possibly ...
10
votes
4answers
203 views

Observed composition of UHE cosmic rays

How much is known about the composition of ultra high energy cosmic rays (say $E>10^{20}\text{ eV}$)? I get the impression that the particles are often assumed to be protons or other heavier ...
8
votes
1answer
1k views

Can you tell just from its gravity whether the Moon is above or below you?

If you are on a place of Earth where the Moon is currently directly above or directly below you, you experience a slightly reduced gravitational acceleration because of Moon's gravity. This is what ...
7
votes
3answers
785 views

How are the 4 km arms of LIGO measured so accurately?

The arms of the LIGO interferometer are 4 km long. Now, LIGO functions by measuring phase difference between two beams of light comming (as in Michaelson's Interferometer) to a sensitivity of ...
7
votes
1answer
340 views

What are the different ways to measure the spatial curvature of the universe?

Just what the question asks. Assuming the Friedmann-Rovertson-Walker (FRW) metric, what measurements can be performed to determine the spatial curvature of the universe.
7
votes
2answers
401 views

How do the LASERs in LIGO realize that space has expanded as a gravitational wave passes by?

I read an article on LIGO, and I heard it mentioned that it is a nontrivial argument to say that the effect can be measured by interferometry. What happens to space as the wave passes? Does the light ...
7
votes
3answers
3k views

Left and Right-handed fermions

Is there a simple intuitive way to understand the difference between left-handed and right-handed fermions (electrons say)? How to experimentally distinguish between them?
7
votes
3answers
327 views

What are the main differences between $p p$ and $p \bar p$ colliders

I know that it is somehow related to the parton distribution functions, allowing specific reactions with gluons instead of quarks and anti-quarks, but I would really appreciate more detailed answers ! ...
6
votes
1answer
871 views

How to prepare a desired quantum state?

Given a quantum state function, we can Fourier expand it in terms of stationary states of the Hamiltonian. So if we want to build that same quantum state approximately all we need to do is to ...
5
votes
2answers
4k views

What is the smallest length scale ever measured?

And, by the way, what is, or are, the measured values?
4
votes
1answer
473 views

How do I calculate the experimental uncertainty in a function of two measured quantities

I am performing an experiment where I'm measuring two variables, say $x$ and $y$, but I'm actually interested in a third variable which I calculate from those two, $$z=f(x,y).$$ In my experiment, of ...
4
votes
2answers
3k views

Strategies against 50 Hz mains hum on detector signals?

I'm having problems with a strong 50 Hz mains hum on signals created by photodetectors. I assume that they are due to ground loops and I realize that the best option would be to remove those. What are ...
4
votes
1answer
787 views
4
votes
2answers
596 views

What are the easiest to get/make LN2 superconductors?

I am starting to build multistage Peltier cooler at the moment, and it should be able to reach -100C at least (but if I fail I can always get boring LN2). Doing some experiments with superconductors ...
3
votes
5answers
478 views

How do we know that time dilation applies to objects other than light?

Here is a traditional derivation of time dilation: There's a train with a lamp in the ceiling, moving at velocity v with respect to an observer. In the frame of the observer, the path taken by the ...
3
votes
1answer
141 views

How to determine the order of indications of a clock?

Given the description of a clock $\mathcal A$, as (1) a set $A$ of all (more than 2) distinct indications of this clock, in no particular order (where the individual indications contained in set ...
2
votes
2answers
330 views

Real World application of Topological Quantum Field Theory

What is a "killer-app" for the formalism of topological quantum field theory in "established real world physics"? To be more precise, I'm looking for an actual physical experiment, state of matter or ...
2
votes
1answer
170 views

Reference request for the terminology and usage of different types of plasmas

I'm looking into discharge models, specifically for combustion prcesses, and I'm swamped by the number of different types of plasmas and their respective treatments (thermal plasmas, non-thermal ...
22
votes
3answers
26k views

Is there a compound denser than the densest element?

I'm musing about how to give students an intuitive feeling about density by letting them lift a same sized volume of different materials, e.g. 1 liter of water, a 10x10x10 cm cube of iron, lead etc. ...
13
votes
1answer
574 views

Could LEP II have discovered a 125GeV Higgs?

LEP II eliminated the Higgs up to 114.5GeV. If it had been run for longer could it have detected a Higgs at 125GeV? I Googled for this without any luck, though I did find a comment that LEP II topped ...
10
votes
1answer
259 views

Are oscillations of electron chirality experimentally observable?

Is there any plausible experiment by which chirality oscillations in electrons could be observed experimentally, such as through some analogy to neutrino oscillation experiments?
7
votes
3answers
356 views

why there is no accuracy of the measured value of $G$?

With the advancement of Modern Technology still there is no accuracy of the measured value of $G$ Gravitational Constant, why!?
6
votes
0answers
153 views

What is the largest number of bosons placed in a BEC?

What is the record for the largest number of bosons placed in a Bose-Einstein condensate? What are the prospects for how high this might get in the future? EDIT: These guys reported 20 million ...
6
votes
3answers
927 views

How are the masses of unstable elementary particles measured?

I am interested in knowing how (Q1) the particle's masses are experimentally determined from accelerator observations. What kind of particles? They must be as far as we know elementary and unstable ...
5
votes
4answers
184 views

Possibility of making an experiment in a classroom to simulate DNA diffraction

I am a TA in a structural chemistry class. The professor want me to show students how Watson and Crick determined the structure of DNA from X-ray diffraction results of DNA crystals. The professor ...
5
votes
2answers
347 views

Accuracy of various optical instruments

I understand that this may not be the type of question allowed here, but I'm not sure. Feel free to close this if you feel that it shouldn't be here I'm planning on carrying out a certain set of ...
4
votes
3answers
555 views

What factors determine whether wind resistance will have an important effect?

What factors determine whether or not wind resistance will have an important effect on the trajectory of a projectile?
4
votes
1answer
184 views

Have general relativistic effects of all of the components of the stress-energy tensor been measured?

The stress-energy tensor is: Have general relativisic effects of all of the components of the stress-energy tensor been measured? I've heard that the accelerating expansion of the universe is due to ...
4
votes
3answers
597 views

Energy of the electron-muon reaction

Lets see the reaction: $e^- \mu^- \to e^- \pi^- \nu_\mu \;\;\;\;\;\;\;\;\;\;\; {(1)}$ I suppose, that this reaction occurs as follows $e^- \mu^- \to e^- \mu^- \pi^+ \pi^- \to e^- \pi^- \nu_\mu$ Is ...
3
votes
1answer
264 views

Rutherford Experiment - practical and theoretical questions

I performed the Rutherford experiment the other day, using Au thin foil of $2\,\mathrm{\mu{}m}$, a source/gun of α particles (241Am) and a detector/counter. α particles were shot from the source ...
3
votes
0answers
173 views

List of cross sections?

Sometimes I need to look up a certain cross section, say the inclusive Z production cross section at $\sqrt{s}$ = 7 TeV. Is there a place where 'all the' cross sections are tabulated ...
3
votes
1answer
776 views

Fitting to a high density scatter plot

I am trying to do a crude particle identification, using a Bethe Bloch tenchnique. Here is a plot I made from the data that I have From what I've read, the standard method to identify charged ...
2
votes
1answer
154 views

With the LHC about to restart as max energy, are there absolutely no hints or tantalizing signs of Supersymmetry in previous data?

Over the last couple of years I've seen several articles talk about hints or bumps in the data that might point to Supersymmetry. An article in NewScientist from Summer 2012 discussed the discovery of ...
2
votes
0answers
43 views

Can a value of “length, in meters” be attributed to a pair of ends which are rigid (but not at rest) to each other? [duplicate]

The definition of the SI base unit "metre" [1] doesn't seem to rule out explicitly that a certain value of "length, in meters" could be attributed to a pair of ends which are rigid to each other, but ...
2
votes
2answers
272 views

Can we have light through out the house with out light being switched on for all the time?

Optical fibres are used to transmit light from one place to the other along curved path in a more effective manner. The optical fibres consist of thousands of strands of a very fine quality glass or ...
2
votes
1answer
357 views

What is 'tilt locking' of a laser cavity?

In another question, jasonh mentions a scheme for locking a laser to a resonant cavity called 'tilt locking': The signal is used for locking the frequency of a laser to a high finesse cavity. The ...
2
votes
1answer
879 views

Enlightening experimental physics books/resources

Most book recommendations I've seen are usually geared toward theoretical understanding. It would be nice to know at least one or two classic experimental physics books. e.g. from Carl Brannen's ...
2
votes
0answers
359 views

Levitation rotation speed involving laser acceleration, pyrolytic graphite and a vacuum

The experment would involve a small NIB magnet levitating between or on the diamagnetic material pyrolytic graphite, unlike other forms of levitation this doesn't require power to run such as ...