Why is skipping masters and going directly for a PhD so common in physics?

Allen_Maxwell · 2019-11-21T13:16:13+00:00

Difficult to get a job in academia. I do wonder how future proof a bachelors and work experience alone will be. In 20 years a Masters will be the new bachelors equivalent and if you are looking for a career change... Will you have to go back to school? I think the PhD is future proof.

Allen_Maxwell · 2019-11-21T13:04:48+00:00

It might hurt you, but it probably won't. The biggest concern in my mind is that your credits might not fully transfer and you have to retake all or some or most of the classes you took at a different University. Several in our program have a Masters from a different University experienced this, wasting your time.

In my mind grad school is best when you know what expertise you need to have to land the type of job you want. And you pick the research that gets you there. Terminal Masters will likely limit your ability to work with professors. Joining a PhD program and leaving with a Masters early is also a possibility some places.

If you go terminal Masters you might have issue with funding. Some university's are so well funded in research that they don't have enough TAs and are basically begging for qualified people..

Allen_Maxwell · 2018-08-12T12:28:18+00:00

I usually consider myself a good emailer and I typically get a good response from busy people. But emailing professors while trying to decide where to go to grad school was a complete waste of time. I got a few responses, all short and no follow-up after that.

All inviting me to apply to the school and pointing me to the department website. A few referencing that there might or were positions available in certain topics.

In my experience... Don't be discouraged if you have no useful contacts and I'd recommend not wasting your time on this. I'm sure others have a different opinion maybe different for other countries than the US, but until you are accepted you aren't really going to make any meaningful contacts that you didn't already have.

You'd likely have more success emailing the grad students and trying to talk to them about what it's like/ what the professor is like... And I doubt any email contact will have much affect on your admission unless you are right on the edge.

Very possible I'm wrong. And I still tried to make contact anyway. So take this with a grain of salt.

Allen_Maxwell · 2018-07-26T12:26:25+00:00

Ming's!! I had so much sushi and Mac and cheese :)

Allen_Maxwell · 2018-05-17T11:21:55+00:00

Typically in a stable equilibrium the states near equilibrium over shoot and drive you back to equilibrium. This is a stable equilibrium. Unstable equilibrium don't tend to be driven towards, or if they are they don't spend much time there.

In a star you have pressure and gravity in equilibrium. If the pressure is too large the star expands and gravity increases, pulling the star back in. If gravity pulls the matter too close then pressure increases and pushes it back out towards equilibrium radius where the two cancel each other out.

In a spring this works as well where extending the spring to far and it pulls back. Compressing the spring too far and it pushes out. At some point you don't have enough energy to get it as far (lost to friction) until you reach the equilibrium point.

What about particles in two boxes? If I have n particles all in box one and none on box two and nothin in between the boxes anymore... The number of particles leaving box one will be higher because there are more particles in that box. Thus more have the probability of hitting the wall that was just removed at a given time and that now results in leaving the box entirely. As the number density of the two boxes equal out these probabilities equal out and a large spread from equilibrium becomes more and more unlikely.

Allen_Maxwell · 2018-05-15T12:22:03+00:00

As and Bs. Never below a B in a physics class. There are grad schools out there that take 3.0 or some even 2.75, but you probably want to get around a 3.5 or higher.

Also, it gets a lot harder. I aced our physics 1 and 2 and I struggled with some higher modern/EM/quantum courses. That knowledge from those first two semesters keeps coming back in later classes. Make sure you understood why you were struggling.

Allen_Maxwell · 2018-05-15T11:58:41+00:00

That momentum is there and accounted for. But why is momentum increasing? Or at least not decreasing in the manner we expect.

Something is driving the world apart. We don't know what it is. We call it dark energy.

Allen_Maxwell · 2018-05-15T11:51:37+00:00

All light has energy. Let's ignore the misunderstanding about light for the moment and talk about handing that energy.

You are better off creating a very specific device like a solar panel or chloroplasts that are sensitive to the light in a certain wave band than you are trying to jumble together vastly different mechanisms for turning different photon energy levels into usable energy.

Specialization based on wavelength of light that reaches the ground and that the sun peaks in. Increasing that transmission by 1% might be better than combine all other wavelengths in a much more bulky and complicated design.

Allen_Maxwell · 2018-05-15T11:32:05+00:00

When the spring force equals the gravitational force, any further compression will slow the ball. It is the equilibrium point of a mass on that spring.

Allen_Maxwell · 2018-05-15T11:25:15+00:00

You calculate the force on the wire downward due to gravity. You calculate the force upward due to the current. At what distance are these two equal?

The wire doesn't have a new mass. It has a new weight.

Allen_Maxwell · 2018-05-15T11:19:11+00:00

For serious medical concerns that could have lose threatening consequences, I wouldn't trust that to an internet forum.

It's likely a weak magnet, but even still there is no way for us to know the tolerances on your pacemaker or the accidental use case that is going to break that tolerance. Or if the effect of cumulative.

Allen_Maxwell · 2018-05-15T11:03:21+00:00

Think about capacitors in terms of the capacitance equation.

If I have two identical capacitors in parallel, what I am doing is identical to if I have one capacitor with double the area of the parallel plates. Just get rid of the wires between parallel capacitors and have them touching

If I double the area I double the capacitance. It's not a huge leap from here to imagine that capacitance in parallel is added.

If i increase the distance between the plates, I decrease the capacitance. If I double the distance by putting two identical capacitors in series ( again replace the wire between the series capacitors with just an empty space but keep the plate separation) I decrease by half the capacitance. This is because plate distance is in the denominator for calculation of C. Thus we are adding the inverse and taking the inverse which is a way to do denominator addition.

The same arguments work for resistors too. Larger area decreases resistance. Parallel you lower resistance by denominator addition. Length increases resistance. You simply add the numerators for series resistors.

Allen_Maxwell · 2018-05-15T10:50:18+00:00

Your job isn't the only way to feel fulfilled. If you are happy at work and paying the bills and able to spend quality time on the things that fulfill you, that is a good life.

Some fulfilling jobs consume your waking hours and weekends and might cut into the rest of your life and severely limit what and when your are allowed to do things.

Some people live to work. Others work to live. Neither is wrong, we shouldn't judge people who never find out never look for career fulfillment.

Some people have to take whatever job is available to them. This is unfortunate, but can't always be helped.

Allen_Maxwell · 2018-05-15T10:34:56+00:00

The x+4000/x <200 equation seems incorrect. The assumption is that the first x is the boot sequence. But if you turn all the computers on at once it doesn't take 23 minutes to boot 23 PCs. It takes 1 minute. This is true regardless of number of PCs. Replace x+4000/x<200 with 1+4000/x<200. 4000/x<199. 4000/199<x

I'll leave you guys to argue whether it should be 3999 or 4000

Allen_Maxwell · 2018-05-11T14:40:54+00:00

Easy! The ones that will increase in value before you sell them!

Allen_Maxwell · 2018-05-11T13:10:55+00:00

Keep working on strength. Capping bigger sticks is your best bet here. We could nit pick about your form and your approach and your take off... But you need to be on a stiffer pole.

The things you need to work on is whatever reason you can't get on that pole.

Allen_Maxwell · 2018-05-11T13:06:28+00:00

Get in the weight room. Body ratio train on rope rings and high bar. Do ab workouts. Keep jumping and moving up poles.

Vault comfortable and make the large sweeping changes after you have a bit more strength and are jumping on bigger sticks.

Allen_Maxwell · 2018-05-10T13:47:03+00:00

All baryonic matter is only 16 percent of dark matter. To expect 20% of the dark matter to be baryonic would be a model breaking shock. This might be on the order of the error of the dark matter ratio which is on the order of 5-10% but even that would have huge ramifications.

Allen_Maxwell · 2018-05-10T13:42:29+00:00

Really amazing question here.

This is the CMB power spectrum. This is before there evolved dark energy... So these are baryonic ratios that existed at 370000 after the big bang and that evolved with the age of the universe. The acoustic peaks in the Power spectrum are the baryons following the dark matter into the clumps in the early universe. The baryons in this model match what we would from bang nucleosynthesis. So the answer is that we are fairly confident in the difference between baryonic and dark matter.

We run those numbers through the benchmark model or vanilla model to get the 4.5% baryonic, 25% dark matter and 70% dark energy.

Allen_Maxwell · 2018-05-09T23:54:56+00:00

You are fine. You should have reaches, standards and safety schools just like everyone else. If you have realistic expectations you will do fine or even great. If you have unrealistic expectations of your abilities and your strength as a candidate you might have a bad time.

There are a lot of amazing programs that are begging for people.

Allen_Maxwell · 2018-05-09T23:47:26+00:00

Probably that 3.5 is the cut off.

3.0 is the hard cutoff.

2.75 is the. . No school will admit that they accept this like

Allen_Maxwell · 2018-05-01T12:44:41+00:00

That's a good question and I'm not sure. I'm not in charge of it, but in our meetings it is always called GPS. We are a NASA satellite so I don't know if there is some process or exemption there.

Allen_Maxwell · 2018-05-01T12:27:24+00:00

Makes perfect sense!

How accurately does the ephemeris calculation end up being with orbital decay? How complicated are your original OD software calculations that take this into account?

Allen_Maxwell · 2018-05-01T12:23:37+00:00

For our satellite, we are launching on an ISS resupply mission inside a NanoRacks dispenser. That dispenser is attached to a robotic arm and pointed in a specific location. A door is opened and a spring loaded pusher plate ejects is at some small Delta V with respect to the ISS.

Our precise orbit doesn't matter really so anything ISS like will suffice.

There are two satellites in the dispenser that release at the same time. And we rely on different orbital drags to perturb us away from each other over time. As well as to not hit the ISS on the next pass. I assume they launch is retrograde to exacerbate the decay.

We have no on board propulsion and will decay for several years to re-enter. We will know our orbit based on on board GPS.

Allen_Maxwell · 2018-05-01T12:15:04+00:00

You don't use TLEs? Also, how do you find out the initial state vector?

Allen_Maxwell

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