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1500 questions
54
votes
3 answers
Why is Microwaved mac & cheese burnt where they touch?
After reheating cold about 1.5 oz. of Annie's Mac & Cheese shells for 15 seconds on high power in the microwave, the mac & cheese was burnt black only at certain points where the pasta is touching each other. Does anyone have an idea of what might…
Zooky
- 521
54
votes
3 answers
Can I use an antenna as a light source?
Can I use a normal metal antenna to emit visible light?
oneat
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54
votes
5 answers
Why do physicists believe that there exist magnetic monopoles?
One thing I've heard stated many times is that "most" or "many" physicists believe that, despite the fact that they have not been observed, there are such things as magnetic monopoles.
However, I've never really heard a good argument for why this…
haroba
- 645
54
votes
7 answers
Why is there no magnetic field around a wire connected to electricity at home?
Is it true that an electric current that flows through a conductor creates a magnetic field around the conductor?
If yes, then why doesn't the magnetic sensor of my mobile device react in any way to changes when I bring the device near to the wire…
Turkhan Badalov
- 654
54
votes
9 answers
How can a photon have no mass and still travel at the speed of light?
I've read a number of the helpful Q&As on photons that mention the mass/mass-less issue. Do I understand correctly that the idea of mass-less (a rest mass of 0) may be just a convention to make the equations work?
From a layperson's view, it's…
user1500
- 565
54
votes
3 answers
Will helium in the tires of a bike make it lighter?
I know that helium balloons float because it is less dense than air. I'm not expecting my bike to float, although that would be pretty cool. I just wanna know if replacing normal air with helium in the tires will produce a noticeable effect on its…
masterwarrior123
- 1,323
54
votes
5 answers
Will a propeller work in a superfluid?
Will a propeller work in a superfluid? Opinions differ.
JDługosz
- 5,297
54
votes
12 answers
Does the Many Worlds interpretation of quantum mechanics necessarily imply every world exist?
I know the Many Worlds interpretation is controversial among physicists, but it's been a pop culture hit nonetheless. I frequently see people making statements like, "Well in another universe I'm a rock star", where you can substitute rock star for…
Nathan Fig
- 675
54
votes
6 answers
Tree-level QFT and classical fields/particles
It is well known that scattering cross-sections computed at tree level correspond to cross-sections in the classical theory. For example the tree-level cross-section for electron-electron scattering in QED corresponds to scattering of classical…
Squark
54
votes
8 answers
Short of collision, can gravity itself kill you?
Imagine that you are falling into object with huge gravity (i.e. black hole) that does not have any atmosphere.
The question is - before you hit the ground, can the gravity itself (which would be extremely huge) kill you? And if so, how exactly that…
libik
- 651
54
votes
3 answers
What's the interpretation of Feynman's picture proof of Noether's Theorem?
On pp 103 - 105 of The Character of Physical Law, Feynman draws this diagram to demonstrate that invariance under spatial translation leads to conservation of momentum:
To paraphrase Feynman's argument (if I understand it correctly), a particle's…
Mark Eichenlaub
- 52,955
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54
votes
7 answers
Is mass an observable in Quantum Mechanics?
One of the postulates of QM mechanics is that any observable is described mathematically by a hermitian linear operator.
I suppose that an observable means a quantity that can be measured. The mass of a particle is an observable because it can be…
Revo
- 16,956
54
votes
3 answers
Why can't I do this to get infinite energy?
I know that I cannot do this because of conservation of energy, so I am looking for an answer as to why this will not work.
So by my understanding of Einstein's whole famous $E=mc^2$ thing it is possible to turn matter into energy, and energy into…
Me2
- 851
54
votes
4 answers
How do we know Dark Matter isn't simply Neutrinos?
What evidence is there that dark matter isn't one of the known types of neutrinos?
If it were, how would this be measurable?
ripper234
- 705
54
votes
5 answers
Are there any theoretical limits on the energy of a photon?
Is there any lower or upper limit on the energy of a photon? i.e. does the mathematical framework we currently use to study photons blow up when a photon surpasses a certain upper limit of energy? (or the same on the opposite side?)
My thoughts: If…
Hritik Narayan
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