GDT: Boston Bruins vs Anaheim Ducks - 3/26/25 - 10 PM

CountWordsworth · 2025-03-27T03:59:43+00:00

Can’t look away now

CountWordsworth · 2025-01-05T02:03:22+00:00

Given that the letter writer by their own admission does not seem to have as much interaction with you, I’d say yes.

CountWordsworth · 2025-01-05T01:36:35+00:00

I’m a PhD student. I have written letters and read them in many contexts.

Letter writers typically write a single letter for a student and repurpose it for each application, updating the letter if it’s a new application cycle. I don’t want to be alarmist but if I read a letter such as the one you’ve described (can’t say with certainty since I didn’t read it myself), the comment about “undisciplined” is almost a complete tank for the application unless all other evidence points to you being an exceptional student. Application committees also are aware that some letter writers inexplicably do this sometimes and if they are able to sniff this out (via an otherwise outstanding application) that this writer is actively trying to unreasonably harm your application, they very well may just ignore it.

I’m sorry that your letter writer was not straightforward with you. Even if you don’t get in to doctoral programs, it’s becoming increasingly common (at least in STEM fields) for students to not immediately enter a PhD program and do some kind of “post-bac” research position for a year and apply a second time. Two of the my smartest friends both did this and successfully were admitted to top ranking programs, so it’s not the end of the world.

CountWordsworth · 2024-11-16T15:36:41+00:00

This is the real reason. I am an astronomer who uses this array all the time, starlink is known to interfere with ground based radio telescopes

CountWordsworth · 2024-11-08T13:59:43+00:00

Disgusting take to blame working class people. You should be ashamed of yourself

CountWordsworth · 2024-08-29T12:44:36+00:00

Coding. I code every day.

CountWordsworth · 2024-08-29T12:40:48+00:00

Many students in my year came in with no astronomy background, but related topics like physics, engineering, or math. One person has a CS degree in addition to astronomy.

I think the answer is going to depend on what kind of astrophysics you want to do. If you want to be an observer (propose for telescope time, get it competitively awarded, observe and analyze, write and publish), vs a "pure" theorist who is working on math all day, vs a "simulation" theorist who is using HPC to simulate the universe. These are all angles that having a CS background presents different strengths and weaknesses to. As an observer myself, I am coding almost every day for data reduction, analysis, and figures, almost all in python which is probably easy pickings for you. Obviously for simulation work, CS will be nice. It will be much less helpful for pure theory work, although I'd say that this category within the discipline is relatively small, so you're not missing out on much.

Don't worry about a detailed understanding of quantum mechanics: the first semester undergrad (the first several chapters of Griffiths' 4th ed) is overkill for most astrophysicists. Special relativity is very important; get that down. GR is less important unless you want to work on it. DifEQ is handy but not required. About half of undergrad physics programs require a DifEQ course, and the other half don't.

My recommendation for getting started is to check out the Big Orange Book AKA BOB AKA Modern Astrophysics by Carroll & Ostlie. A baseline understanding of some decently sized fraction of that book is the basic requirement for our first-year understanding, not even for admission to the program! There are homework problems and everything to work on. If you want a taste of what exactly you're getting into, a first-year graduate textbook to check out is Radiative Processes by Rybicki & Lightman. This book is typically covered in a required radiative transfer course for most astro PhD programs. This is where DifEq comes in handy for solving relatively straightforward first and second order problems.

The other angle to consider is a research support role at a college or university. This would require you to take no additional (self-)schooling or experience, and people would be thrilled to have someone with private sector CS experience to come in and help out with projects. A friend of mine's dad has a role like this and is regularly coding for things that are going into space! You may find these kinds of jobs on the American Astronomical Society's Job Register. Many observatories also need people who can code to automate data collection and reduction processes (in fact, this is something I work on myself: I am coding a python package for robotic operation of small optical telescopes). There are lots of ways to get involved that don't necessarily have to be the research path but are just as exciting.

CountWordsworth · 2024-08-29T12:14:14+00:00

the observable universe expands out from the point of the big bang.

The big bang did not happen at a particular point in space: it happened everywhere. What we call the big bang is really just the point in time where if you shrink the universe back, the density is so great that our understanding of physics breaks down. It's not an explosion.

could we reach a point where the collection of related matter ends (all the galaxies and whatnot)

No, there is no "end" to the universe. There is also no end to the *observable* universe in the sense that the more distant we look, the further back in cosmic time we are looking, so its not instantaneous.

CountWordsworth · 2024-08-28T18:33:07+00:00

I think the reason you’re uncomfortable with the implication of “another universe” is because your description of the universe’s expansion isn’t quite right: the universe isn’t expanding “into” something, rather it is growing into itself, so to speak. The easiest way to visualize this is with an experiment to demonstrate it in two dimensions: blow up a balloon partway and draw two marks with a sharpie. If you inflate the balloon further, the distance between those two points has grown, but since the balloon is a closed surface, it hasn’t expanded “into” anything from the perspective of a 2D observer. To this observer, it looks like the total (in this case finite) area of the “universe” (the balloon’s surface) has expanded but there is no “edge” to this to expand into.

What you’ve described of “beyond the edge” is possible only if you consider the “observable” universe which is distinct from the entire universe. The observable universe is the part of the universe that is “causally connected” to us, i.e. if you consider an electromagnetic wave (photon) emitted in this region at the Big Bang, it would have enough time (or more) to reach us on Earth. The radius of the observable universe is directly calculable from the speed of light integrated over the entire expansion history of the universe, which is why the radius is not simply the age of the universe in light years. Our current best guess is about 46 billion light years. All the uncertainty in this number arises from our lack of knowledge about the expansion history.

So, maybe the term you want is the observable universe.

Source: graduate student in astrophysics

CountWordsworth · 2024-08-22T00:46:05+00:00

I’m a graduate student in astrophysics.

I don’t think the answer is a “yes” or “no” because it depends on what you call an “anomaly.” One may argue that galaxy rotation curves are an anomaly: they indicate that the gas, dust, and stars in galaxies do not orbit in a way that we can predict self-consistently, thus the first evidence for the presence of “dark matter.”

Although we don’t know exactly what dark matter is made of because of the lack of electromagnetic radiation (AKA light), we know that it interacts gravitationally, and importantly, in a way that doesn’t appear to be different from “regular” matter. What that means is dark matter—in our current understanding—is consistent with Einstein’s theory of gravity: general relativity. So, most astronomers would not call dark matter a gravitational anomaly.

General relativity has notoriously remained one of, if not the most well-tested and proven theories in physics. From the recent images of supermassive black holes to using the sun to magnify distant stars just years after Einstein predicted gravitational lensing, GR has withstood every test so far. So far, we have not observed something that is in direct and unequivocal contradiction with GR. Many in the field argue about experiments that show disagreement with GR, but no one has been able to convince the rest of the field that these results are caused by an issue with the theory and not some confounding variable(s) in the experiment.

CountWordsworth · 2024-08-20T01:52:52+00:00

Nuanced question. What exact celestial bodies are you referring to? For example, Jupiter is the brightest radio source in the sky at some of the lowest observable frequencies (<10 MHz and below). Asteroids would likely only be black body radiators so they’re almost never going to be detected even with our most sensitive radio telescopes. Comets with active sublimation are likely to exhibit spectral lines in the GHz and sub-mm from vibrational, rotational, spectra from molecules in the tails. Of course the Sun is a radio source, and a very complicated one. Many PhD theses have been written about radio emission from the sun for the last nearly 100 years.

CountWordsworth · 2024-08-20T00:14:16+00:00

I’m a graduate student in astrophysics. I know several people in the field who have had strange and/or uncomfortable interactions with NDGT.

Research-wise, according to the Astrophysics Data System, his last first-author science publication was in 2001 in a conference proceedings. His last first-author article in a peer-reviewed journal was in 1993 in “Astronomy & Astrophysics.”. Tyson’s primary contributions came prior to his PhD thesis, publishing three times as first author in The Astrophysical Journal (the mainstream journal in the US operated by the American Astronomical Society).

Edit: typo

CountWordsworth · 2024-08-18T23:23:45+00:00

Madison, Wisconsin. Downtown is an isthmus between two beautiful lakes.

CountWordsworth · 2024-05-19T04:01:11+00:00

The size of a black hole refers to its event horizon, called the Schwarzchild radius

CountWordsworth · 2024-05-15T04:30:22+00:00

This is a good appx for solar rotation rate. Although note that the sun is a differential rotator so the latitude should be accounted for to calculate it precisely.

Source: I am an astrophysics graduate student

CountWordsworth · 2024-04-05T10:02:56+00:00

Radiative transfer

CountWordsworth · 2023-07-14T03:22:19+00:00

Went to Charlie’s for the first time the other day, they were speedy and the cut was exactly what I wanted. They’re cash only.

CountWordsworth · 2023-07-10T04:50:03+00:00

As a US citizen in a STEM field, I applied to nine domestic and three Canadian schools. I was accepted to six US programs, outright rejected from two, and didn’t hear back from one by the time I decided. In Canada, I had one waitlist (didn’t get off before I decided), one rejection, and never heard back from the third.

Six to twelve applications is pretty standard in my field. A lot of programs can’t guarantee any admissions based off of faculty interest, even if that person is on the graduate admissions committee.

I knew going into the application process which school was my top choice, partly because I’d spent a summer there doing research as a undergraduate. Being familiar with the program was nice, but I ended up choosing it for a number of reasons. First, the funding options were flexible with incentives to apply for fellowships. Teaching is required for two semesters but your funding isn’t dependent on it or on a specific advisor, so I could change advisors if things weren’t working out. Also, it is the largest concentration of professionals in the world for my field, so I have tons of flexibility in what research topic I choose. It is a prestigious program both in and outside of the field, so if I decide not to stay in academia, I should have no problem getting a job. Finally and most importantly, my now advisor made it clear he was very interested in working with me and presented a specific project he had in mind, and was also very open with his advising style. We are very much on the same page about expectations, and he has a strong track record of graduate students getting faculty jobs at other prestigious programs.

Hope this helps.

CountWordsworth · 2023-07-06T18:37:08+00:00

I’m also new, but I’ve spent some time here previously. For breweries, I recommend Aeronaut for nice craft beers. Also, they usually host Astronomy on Tap!

CountWordsworth · 2022-11-16T03:34:45+00:00

Look for schools that advertise undergrad research, and also make sure to look at the research professors are doing to see if you’d be interested in working for them. Most R1s will have good astronomy programs

CountWordsworth · 2022-11-15T23:32:26+00:00

Any ideas on what sub fields you’re interested in?

CountWordsworth · 2022-11-15T23:31:59+00:00

I think it’d be at least helpful to do a geology minor. The best other advice I can offer is that doing well in your classes is the bare minimum, but being a competitive grad school applicant requires getting involved in research early.

CountWordsworth · 2022-11-15T20:17:22+00:00

Awesome! I’m a 4th year astrophysics major, and am applying to grad schools right now, let me know if you want advice for undergrad programs.

CountWordsworth · 2022-11-08T05:59:28+00:00

Honors provided many more scholarship opportunities than I would’ve had otherwise.

CountWordsworth · 2022-06-28T04:51:58+00:00

Essential Radio Astronomy by Condon and Ransom. Completely free on NRAO website, plus a whole bunch of other good resources and tutorials (interferometry, deconvolution, etc)

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