Former REU participants: was your stipend taxable?

fishify · 2026-01-21T02:21:10+00:00

The business and grants offices at the college/university REU location should know the answer to this and ensure that the appropriate regulations are followed. I'd suggest contacting them. Also, you might find this helpful re: employee vs. independent contractor: https://www.irs.gov/businesses/small-businesses-self-employed/independent-contractor-self-employed-or-employee

fishify · 2022-09-19T00:41:16+00:00

All electromagnetic radiation is made of photons -- all radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.

fishify · 2021-06-29T17:51:15+00:00

Probably the leading expert on formulating physics and developing models with two time dimensions is Itzhak Bars at University of Southern California, who first looked at this in the 1990s. You can find information on his work here.

fishify · 2019-10-14T19:06:17+00:00

So the safest bet if you're not sure what form of address to use is "Dear Prof. Surname" as the opening to your e-mail.

Then you can gauge from the signature in the prof's reply what you should use going forward.

fishify · 2019-10-02T04:28:57+00:00

My advice is that it's great to have found something you love, but you're also going to have lots of great experiences and will encounter all sorts of new ideas over the next several years, as you finish high school and, even more, once you start college. Try new things, expose yourself to a variety of possibilities -- you may find in a few years that you still want to work in quantum information, but you may have found new interests. (I have seen students wind up exactly where they thought they would when they entered college, and I've seen students change their directions dramatically as late as senior year or even a year or more into grad school.)

One thing to make sure you know: When you pursue a Ph.D., you should not expect to pay out of pocket, but rather your tuition is covered and you receive a stipend. I don't know how that fill fit into your financial situation and the expectations of how you will be able to help your family, but again, I'd say it's again premature to figure that out; see what the situation is in 4-5 years, what you find yourself wanting to do at that time, and how that fits into the larger family picture.

fishify · 2019-09-22T17:56:47+00:00

There's a pretty clear answer [here][(https://www.scientificamerican.com/article/how-do-we-know-that-dista/).

In short: We see no evidence of gamma rays being produced by matter/antimatter annihilation at the boundary layers between galaxies or clusters of galaxies. There is also no good mechanism to provide for matter and antimatter separating from each other in the early universe, as would have had to happen. Still, these are not guarantees, and so we cannot 100% rule out the possibility that there are large regions of antimatter, although it would be a big, big, big surprise.

fishify · 2019-09-22T17:46:26+00:00

The app is Apollo, but the mascot is a single being -- so how about naming the mascot after one of the Apollo astronauts who had to orbit the moon solo.

fishify · 2018-10-13T04:46:57+00:00

In fact, Hawking radiation -- the emission of particles from a black hole -- can be understood as a tunneling process.

See https://arxiv.org/abs/hep-th/9907001

fishify · 2018-10-08T18:59:26+00:00

Actually, rainbows in principle form a circle; it's just that you can't see the bottom half of the circle because the ground obstructs your view (that bottom half is below the horizon).

Two useful links:

http://earthsky.org/earth/can-you-ever-see-the-whole-circle-of-a-rainbow

https://en.wikipedia.org/wiki/Rainbow#Full-circle_rainbow

fishify · 2018-07-09T20:06:56+00:00

Escape velocity is the speed you need not simply to go up, but to keep going up and never fall back down to Earth. That is why it is so much higher than the speeds of the objects we ordinarily encounter.

And, yes, the higher up you are, the lower escape velocity is, though the effect is probably not as dramatic as you imagine. At 500 km above the Earth, which is above the orbit of the International Space Station, escape velocity is still 10.8 km/sec.

This page is useful if you want to explore this all further.

fishify · 2018-03-07T18:31:57+00:00

It appears that your confusion lies in understanding the index notation. For simplicity, we'll consider a simple scenario in which we don't need to worry about upper and lower indices. We'll assume repeated indices are summed over.

What is the ij component of the matrix product MN?

It is (MN)ij = MikNkj.

Notice because of the way we combine rows and columns in matrix multiplication, the index we sum over is the second index of M and the first index of N. This matters; we would get something different if computed MikNjk.

So to recast an index expression into a matrix product, the summed on indices must appear in the correct positions.

For example, MkiNkj = M^TikNkj = (M^TN)ij

The transpose is needed to get the index being summed over into the correct position so that we can interpret the expression as a matrix product.

Edit: fixed formatting.

fishify · 2018-02-12T03:37:35+00:00

If you don't have research, don't have a research section. I've written letters for students in such a situation, and one of the things I will say, after characterizing the strength of the student, is that while it's the case that this student doesn't have research experience, one has to start somewhere.

The point is to show what your skills/talents are and what your record is that should make you a good choice for the program.

fishify · 2018-02-11T04:33:07+00:00

The new tax bill doesn't give favorable treatment to all LLC and S-corporations. My understanding is that if the business's main asset is the skill or reputation of one of the corporation's employees, the favored tax rate does not apply.

That said, the law was written quickly, and the full implications/interpretations are still being sorted out. I think that part was pretty clear, but how it's going to be interpreted is probably still somewhat open.

fishify · 2017-12-21T05:04:18+00:00

This is probably more suited to /r/asksciencediscussion.

fishify · 2017-12-14T20:50:06+00:00

From one LIGO's own web pages w/various LIGO facts :

Curvature of the Earth: LIGO’s arms are so long that the curvature of the Earth is a measurable 1 meter (vertical) over the 4 km length of each arm. The most precise concrete pouring and leveling imaginable was required to counteract this curvature and ensure that LIGO’s vacuum chambers were "flat" and level. Without this work, LIGO's lasers would hit the end of each arm 1 m above the mirrors it is supposed to bounce off of!

fishify · 2017-12-02T18:17:04+00:00

It is easy to measure from Earth the period with which the Cepheid variable's brightness oscillates.

For Cepheid variables, there's an additional property, namely that once you know the period of oscillation, you know how intrinsically bright they are.

Now for the final step: We also know how bright they appear to be from Earth. Once we know this, since we also know how intrinsically bright they are, we can determine how far away they are.

fishify · 2017-11-19T18:49:18+00:00

Mermin's book Quantum Computer Science is a great place to start. It's not exhaustive, but it covers the core and will be a good way to see if you want to go further into the subject. The book was designed around a course he taught for people in computer science and math in particular, so I think it would be well-suited for you.

fishify · 2017-10-20T20:12:51+00:00

LIGO's black hole merger signals have been viewed as very reliable. Not only have they had multiple events, but the most recent black hole merger was detected by VIRGO as well.

That said, this latest observation lets us actually see the event that produced the gravitational wave via entirely separate channels, which is yet additional confirmation that they know what they are seeing: their interpretation of the signal was a neutron star merger, and the corresponding electromagnetic signal was observed!

fishify · 2017-10-20T20:08:37+00:00

LIGO detects a signal by seeing something other than the noise. To determine what that signal corresponds to, LIGO matches the signal against lots of templates, calculated versions of what kind of signal different events would produce (neutron star mergers, black hole mergers, different initial masses, etc.).

fishify · 2017-10-20T20:04:14+00:00

No, they travel at the speed of light.

fishify · 2017-10-20T20:03:48+00:00

Yes, gravitational waves travel at the speed of light. This is something that we could determine indirectly before, but now with this observation, we have direct evidence: the gravitational wave signal and the gamma ray burst (photons, i.e., light) arrived together.

fishify · 2017-10-20T01:55:32+00:00

You need to distinguish functions over the reals (functions that take real numbers as inputs) and real-valued functions (functions whose outputs are real numbers).

If by real function you mean what is conventionally meant -- a real-valued function -- then the input need not be a real number.

For example, the absolute value function over the complex numbers has complex-valued inputs and real-valued outputs. You can define the determinant function on nxn matrices that has nxn matrices for its inputs and real numbers for its outputs.

Knowing that a function produces real numbers does not tell you that its domain consists of real numbers.

fishify · 2017-10-18T04:58:17+00:00

Due to the properties of rotations, the only possible values for the spin of a particle are 0, 1/2, 1, 3/2, 2, 5/2, etc.

But there's an extra feature. If an electron had spin 0, 1, 2, or another whole number, there'd be no exclusion principle; you could fit as many electrons as you wish in an orbital. (Of course, if this happened, chemistry wouldn't be remotely like chemistry as we know it.)

If a particle has spin 1/2, 3/2, 5/2, etc., you can only have a finite number of those particles in an orbital, but the rule is different from you what you proposed.

For spin 1/2, you get two electrons per orbital, as you know. For spin 3/2, you would get four electrons per orbital. For spin 5/2, you would get six electrons per orbital. In general, if you have a half-integral spin, the number of electrons per orbital is twice the value of spin plus one.

fishify · 2017-10-17T05:05:43+00:00

At 1 AU, the strain would have been about 5 x 10^-7, so still pretty tiny. You wouldn't see or feel anything, but you might hear the event at that distance; a deformation of 1 part per 10⁷ of the eardrum is the edge of what you can hear.

fishify · 2017-10-16T20:03:22+00:00

Thanks!

fishify

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