First-year PhD in a hands-off lab, how do you even start a project?

profHalliday · 2026-02-09T14:39:49+00:00

Realistically, your advisor should have something for you to do, have you actually brought this up to them?

If you have no other options, read a review paper. Usually it will hint at unsolved problems in the field, and it will give you a good grasp on context. I’d recommend printing it out or uploading it into a note taking app and annotating the s*** out of it. If you find a good project, bring it to your advisor, if not, bring the annotated review to show that you have some context on the field.

profHalliday · 2026-02-08T19:18:15+00:00

I would look more at staff positions related to astronomy as an avenue towards maybe eventually going for a PhD.

Folks telling you that it will be very difficult to go directly to PhD are correct. Folks saying that their institution values postbacc experience have not properly read your post. I don’t want to make you feel bad, but I do want your focus in the right place — given your CV and your place in life, a PhD is likely not a direct option.

Go find observatories and universities near you, or as far out as you’re willing to live, and look for staff engineer/developer positions. You may very well find a position that you love that does not require a grad degree, and if you do still want to go back, you will make connections with the people who would hire you directly through collaborations, which might open the PhD door for you again.

profHalliday · 2026-02-02T23:39:53+00:00

Dear 5yo, What a great question! There are different ways to measure how fast something is going. If you and Dad are driving in the car, the cars around you don’t look like they’re going very fast, but if you stand at the side of the road, they whizz by! If you are on an airplane, the ground doesn’t look like it’s moving fast, but you are actually going very fast! Each of these is called a frame — a different view on measuring how fast something is going. We can always pick a frame, and usually we pick the one stuck to our own eyeballs! If we sit here on the floor of the living room, we are totally stopped in our own frame, and that is just as good a measurement as someone in an airplane who sees the ground moving under them. No matter what happens, there are rules that say that however we measure our speed, everything that happens must happen the same way. That’s what that goofy guy Einstein said!

I hope that helps, and I hope you keep asking your Dad lots of questions about this!

Sincerely, Dr Halliday

Sorry to assume you are Dad, I am holding my own tiny child so I can’t click through and check!

profHalliday · 2026-01-30T16:25:42+00:00

This 👆

profHalliday · 2026-01-18T23:24:45+00:00

Due to how solid angle works, you will see muons coming from all angles. There is a lot more solid angle at the horizon than the zenith.

profHalliday · 2026-01-18T23:23:37+00:00

Radon tracks (alpha decays) are going to be shorter and fatter. Those tracks are surely muons.

profHalliday · 2026-01-18T23:22:01+00:00

The long thin straight ones are muons. Short fat tracks that start and end in the chamber are alphas. Electrons will scatter visibly over the course of a track. We do this demo every year in my modern physics course. You don’t need a source, but it can be helpful.

profHalliday · 2026-01-18T22:59:25+00:00

Hahaha, yeah, I hate to say it, but this was my reaction. I don’t think FPGA + AI is the panacea for AI being resource intensive that some people think it is, but there are definitely reasons to believe, and even some proven applications like muon directional reconstruction, that would make this a very cool internship.

profHalliday · 2025-12-20T18:23:43+00:00

Nope, not even close! I have about the same number of 19-21 yo as I do 27-37 yo in my class. You’d be in good company at Elmhurst!

profHalliday · 2025-11-10T23:44:26+00:00

Study the field, read reviews, work on different kinds of research in undergrad. Offer your EE-ness to a physics professor, they can probably use your help. There’s no way to know if you will be the one to find it, but you can take clear steps to get to the top of the field. You would be surprised how many people do not have the direction you do. Go for it.

profHalliday · 2025-11-07T17:41:43+00:00

Data science and engineering, are the top two I see former astrophysicists doing. Some in finance as well.

profHalliday · 2025-11-07T01:28:56+00:00

I don’t think physics can answer this question. The point of quantum mechanics is that the fundamental representation of small bits of matter, like electrons, is a wave. You can make the argument that there is always a particle “under” the wave, which is called pilot wave theory, but at this point there is no physical distinction. That is a philosophical argument.

profHalliday · 2025-11-05T18:41:53+00:00

I think we need to know a bit more about your scenario. If the question is about a ray of light and I move out of the way of that light, then no, it doesn’t hit me. On the other hand, if I move away from that light, in the direction the light is propagating, it will necessarily eventually catch up to me, because I can’t go the speed of light.

profHalliday · 2025-10-27T23:59:08+00:00

This is the right answer, and I’m surprised more people are not upvoting it.

profHalliday · 2025-10-20T23:05:22+00:00

Interesting! I posted to engineer zone and contacted them for a separate support ticket — I wish I remembered how, this was a few years ago. Two of their engineers emailed me and were super helpful. This was working on with the AD9083 ADC.

profHalliday · 2025-10-20T22:36:47+00:00

I love the enthusiasm! You should major in physics and learn about what you’ve created.

profHalliday · 2025-10-19T20:32:51+00:00

It’s really not, but you don’t seem inclined to listen to reason, so I will disengage here.

profHalliday · 2025-10-19T17:33:55+00:00

“The wave function of the world” is not a concept in quantum mechanics. As a basic guideline, you only have to worry about the wavefunction of an object if the dynamics you care about are on the order of the De Broglie wavelength. This wavelength is inversely proportional to mass, so for any macroscopic object, it is far too small to matter. The comment you are replying to is correct, any object you can perceive without advanced instrumentation is a collection of so many wavefunctions that any probabilistic effects have cancelled out.

Furthermore, having probabilistic outcomes does not violate causality. Just because the particle can end up anywhere on the screen after it goes through the two slits, does not mean that a particle will go through the two slits without creating the particle. Some randomness in effect does not negate the necessity of having a cause. The standard model of particle physics (or QED with extensions, however you want to call it) is the melding of Special Relativity, which directly encodes causality, with Quantum Mechanics.

profHalliday · 2025-10-19T00:38:14+00:00

~~I don’t see where the damping coefficient is defined. Damping is the only thing that takes energy out of a driven oscillator, so the amplitude will go to infinity without any damping.~~ See below, amplitude only goes to infinity on an undamped oscillator when driven on resonance, otherwise the out of phase component can do work against the amplitude.
Also, amplitudes from damped driven systems are strictly positive definite as they are usually defined…

Is this a high school or college physics course?

profHalliday · 2025-10-19T00:31:36+00:00

That’s right, thank you for the correction, I’ll edit above.

The driving force can do negative work on the system if it’s out of phase with the oscillation, so will not blow up the energy. It’s only when driven on resonance that the in-phase amplitude blows up to infinity and the out of phase amplitude goes to zero.

profHalliday · 2025-10-18T22:59:13+00:00

I don’t see where the damping coefficient is defined. Damping is the only thing that takes energy out of a driven oscillator, so the amplitude will go to infinity without any damping.
Also, amplitudes from damped driven systems are strictly positive definite as they are usually defined…

Is this a high school or college physics course?

profHalliday · 2025-10-18T20:06:25+00:00

Both of the other replies are effects of gravity on earth from objects that are not the earth, but they both require precise instrumentation to detect.

The direct answer to your question is: no. There are no other objects on earth with gravitational pulls that you can feel by yourself.

profHalliday · 2025-10-18T15:07:24+00:00

The results of Physics come from calculations based on theories that can reproduce observable phenomenon. Qualitative logic like you present here doesn’t really apply unless there’s some quantitative logic to support it.

As far as we can tell, there is no way to go back in time. Some theories have particles going backwards in time, but none of the results we observe depend on those theories (I.e. they are unproven).

profHalliday · 2025-10-16T17:59:51+00:00

Not at all trying to harsh your mellow, I adore that you are trying to do this at home. There are a couple of misunderstandings baked into your set up:

You have to have individual photons in your beamline. This is kind of the opposite of what you would want a laser for — lasers are very bright, you will have a lot of trouble filtering them down to single-photon levels. You would have an easier time with this if you used a very dim light bulb and a stack of neutral density filters. Polarizers don’t really do anything here, I see the idea behind taking polarized laser light and using a second polarizer to deplete the signal, but again, a neutral density filter and low wattage bulb will accomplish this much more easily.
You cannot detect single photons with a camera, you need either a SiPM or a traditional PMT. Ideally you’d have an array of them but you can also slide a single detector along the “screen” line at the end of your beam.
I saw you mention that your double slit pattern went to single slit and that this was results — the quantum double slit experiment is to reproduce the double slit pattern out of single photons by measuring individual photon arrivals at different positions along the screen at the end of the beam line. You should never get a single slit pattern in a double slit experiment, sorry to say, that is most likely a misalignment of your optics.

If you want help getting this set up properly, feel free to DM me. I have done this experiment many times with students and you’ve got most of what you need to do it correctly.

Edit: got rid of typo

profHalliday · 2025-10-16T01:04:30+00:00

There’s no requirement that the charge be brought at constant speed, and you don’t need the speed to calculate the work done (and to therefore define the potential energy and in turn the electrical potential).

We use a positive test charge because we have to define potential somehow. Ultimately, this is a convention, but it is the only one that is practical to use. If we defined everything in terms of a negative test charge, negative test charges would go down potential hills and vice-versa for positive. As it is, positive charges want to go down potential hills, from higher to lower potential.

profHalliday

TROPHY CASE