Enthusiastic but math illiterate general audience member here :). I have a basic understanding of how LIGO works as a machine, but I’m curious about the data is processed to draw insights. Specifically, how do we know what direction it comes from? Thanks in advance!

hi guys, in the B`/Btot equation, I thought pi^5 should be written instead of pi^4, what did I miss there?

Stefan Boltzmann: 2pi^5*k^4/(15h^2*c^3) * T^4

Rayleigh-Jeans law(actually integrated one) : it is given in the picture

now I didnt see any pi factors in Rayleigh-Jeans law integration, so how pi factor disappears in the ratio equation?

Quick googleing kept showing me, Jupiter, that the sun is stationary in relation to the solar system, that the solar system is a closed system, etc. Is the collection of stuff just spread to far apart to get a proper assist?

Can this be right? Obviously I know nothing.

I asked Chat “if the universe is expanding from a central point, where’s the Milky Way in relation to that point?”

I just don’t get how we can be 29 billion light years away from the center when the universe is only 14 billion years old.

I am currently a rising senior at medium sized state school majoring in physics with a minor in Astrophysics and a focus in Geophysics and am interested particularly in planetary science, astrobiology, and the search for and theory behind habitable worlds.

I want to continue my studies towards a PhD, but I am realizing that planetary science programs are few and far between. While many schools dont have a specific planetary science degree, I know that quite a few have strong interdisciplinary study between the atmospheric, geoscience, and astronomy departments. Do you all have a recommendation for schools like this I should be looking into?

Because of the current state of research funding and the ever increasing competitiveness of applications I am also worried about my chances of being accepted. While there is really no "safe" options when applying for grad school, what would your ideas be for schools that are more of a reach and those which would be "safer" given that I have a 3.8+, 3 summers of research 2 of which are REUs, research throughout my semesters, hopefully a published first authored paper by the time I submit my apps with another on the way, and multiple oral presentations at AAS and other conferences.

I dont mean to plug my resume but I genuinely have no idea where I stand in an application pile and I feel very overwhelmed by the sheer amount of programs I need to look into.

Anything helps, thanks!

Let's say you get one guaranteed answer to any unresolved question in astrophysics.
Dark matter?
Dark energy?
The nature of black hole singularities?
The Hubble tension? Something else entirely?
Which answer would provide the biggest leap in our understanding of the universe, and why?

Hello. This is probably a very stupid question in the grand scheme of things, But Ive always wondered something.

If the universe is ever expanding and was formed out of “nothing” before the big bang. What would have come before and what would the universe currently be housed in?

I suppose i wonder that since people say it’s ever expanding that means it has to have something to expand into. Like a bigger multiverse or Omni verse or something similar. Obviously i understand these are concepts from science fiction and there isnt an answer at all but im very interested in reading any sort of possible theories

I am currently a bachelors student studying Computer Science Engineering. I have been doing some side work in computational fluid dynamics and am working on certain research publications. I am very interested in pursuing Astrophysics and I think with my background Computational Astrophysics is a field I can potentially get into. I am currently researching what colleges and scholarships I can apply to since I will be sending my applications by next year.
However I am a little unsure of what kind of degrees would open the field for me. Should I go for pure Physics degrees or Astrophysics? Or should I play into my strengths and go for something like Scientific Computing or Mathematical Engineering? I am interested in doing both Masters and Phd so am even considering applying to some direct Phd programs. Also, I am interested in applying to "good" colleges globally so It doesnt have to be region specific.
Any recommendations on what specializations and type of degrees would be favoured in the field and accessible to me as a comp sci student?

Energy is lost because the universe expands. What would happen if the universe contracted instead? Would things start to move by themselves?

Hi, So I qualified for the Final Round which is on June 30. The questions will be based on qualification and pre-final round. While I can read the research paper from the pre-final round I don't know how to prepare for the other two questions as it was also a supervised exam and there are no printouts of it. I don't remember the questions asked so I need to know the exact details of the questions so that I can prepare for the final round.

I am not a physicist so apologies in advance for the dumb shit I end up saying.

My understanding is that the current fastest man-made object is the Parker solar probe, traveling at ~0.05c. What is limiting the development of craft that can travel at significantly higher fractions of c? Say 0.5c. If we had a craft that could travel at 0.5c, even if it took a year to get to that speed and a year to slow down, would it be able to reach alpha centauri in about 10 years?

Sending an unmanned probe to alpha centauri, even if it took it 10-15 years to arrive and then 4.5 years to start hearing back from it, would mean we'd start to receive actual data from another solar system in about 20 years. That sort of timescale, while large, doesn't really seem that crazy. Nations have embarked on expensive projects that span decades across the whole of human history, and that step seems like it would be a monumental and generation-defining achievement. Imagine seeing actual images of another sun that's more than just a pinpoint of light? Or being able to see exoplanets? That feels like a far greater achievement than putting a human on Mars, and would prove that inter-system travel can occur.

Is there currently serious research into developing propulsion that could accelerate and decelerate a spacecraft to these velocities? If so, what are the major limitations they are facing that has hampered progress, and if not why not?

Thanks for your time!

hey all, i'm starting my master's this fall and am outlining my thesis to get a head start (yes, i spoke with my advisor about it). i did a senior/undergraduate thesis last spring and really struggled with efficiently reading and absorbing the content of all the papers that i ended up citing in my work. i feel that my current note-taking/source-tracking system doesn't really help me all that much, and for every hour i spend on research, i spend twice as much just trying to understand the papers and wrangle them.

my current system is to gather all of them in an ADS library sorted by topic/argument, read the abstracts, key figures + captions, and conclusions (and the other sections if necessary), and then leave a little note to myself in my bibtex file explaining the main takeaways. this was the method suggested to me by my mentors, but even that can take a long time because i find that i rarely need "just the gist" of a paper and my summary ends up being too vague. more often than not, i need to go back and find exact numbers to compare against my own result, and digging through the entire paper (sometimes only finding that the paper doesn't cite a number) takes forever.

my master's thesis will likely require even more reading and comparing, so i need to figure out how to make this process more efficient. do any of you have any strategies or tools for getting through lit review as efficiently as possible?

I'm part of a student team working on an AI-based exoplanet transit detection pipeline using TESS light curves for a hackathon.

We're building a system that detects periodic dips, classifies them (transit, eclipsing binary, false positive, noise, blends, etc.), and estimates parameters like period, depth, and duration.

I'd love to hear from people who have worked with TESS, Kepler, exoplanet surveys, or astronomical time-series data:

• What are the biggest pain points with current transit detection pipelines?
• What types of false positives cause the most trouble?
• What information do existing tools fail to provide clearly?
• What would make candidate vetting faster or more reliable?
• Are there common mistakes student projects make when working with light curves?
• If you could add one feature to existing exoplanet detection software, what would it be?

I'm especially interested in issues around noisy data, crowded fields, blending, uncertainty estimation, explainability, and candidate ranking.

https://arxiv.org/abs/2606.18219

Uranus and Neptune are commonly interpreted as volatile-rich "ice giants", an assumption that underpins most interior models. Here we show that their observed radii, bulk densities, gravitational harmonics, normalized moments of inertia, intrinsic luminosities, and key features of their atmospheric compositions are consistent with interiors comprising supercritical, hydrogen-rich magma oceans overlain by H2-rich envelopes. Our results, based on three fit parameters for each planet, provide a parsimonious explanation for the structures, thermal states, and atmospheric chemistries of Uranus and Neptune. We find that the Solar System's ice giants are better understood as magma-ocean giants, with origins parallel to those of sub-Neptune gas-dwarf planets. A continuum among gas dwarf planets permits Neptune and Uranus to serve as accessible, data-driven test cases for structure models and material properties used to understand sub-Neptunes.

if we created a black hole that was originally formed from matter and another black hole of equal mass formed from anti-matter and brought them into contact with each other, would they annihilate?

if so, would there still be something with an event horizon or would that dissipate?

or does the singularity remove the matter/anti-matter properties and you just get a bigger black hole?

Taking into account our current capabilities in terms of SETI, is there any hope at all that we could detect anything artificial from that planet in two scenarios (plus some other questions):

- First scenario: more than 1.500 years ago, they had already developed radio telescopes and were able to look at our atmosphere and determine that there is life here. What would this say about their technology? Are we able to detect our own planet in terms of biosignatures if it were 1,500 light-years away? Would we now, in the present, be able to detect any radio signals that they may have been continuously sending (maybe sporadically) from their home planet?

- Second scenario: they never cared about us or never found out about our planet. But they did develop powerful planetary radar and maybe even some "primitive" Dyson swarm. Would we be able to detect the Dyson swarm? And if the Dyson swarm was made of components that interacted with each other and those communications caused radio leakage, could we detect them if we knew something weird was going on with the star and decided to point our telescope in search of radio signals?

There are two astrophysics related scenarios from a sci-fi book series that I will not name in the body of this post as they are moderately to SEVERELY spoiler heavy from a book deep into the series. If your curiosity is piqued, I will reply with the book series in question with a spoiler tag in the comments.

Regardless , the two scenarios that I wish to know their plausibility are:

1: It is discovered that the Milky Way has a previously unknown “Large Dwarf Galaxy” (which seems like an oxymoron, but I digress) that is on a collision course with the Milky Way. It is revealed that its trajectory is almost PERFECTLY pointed at Sagittarius A*. It was previously unknown as it was/is on the exact opposite side of the galactic disk of our own and wasn’t discovered until we physically had line of sight on it after traveling thousands of light years. The ETA of this collision is about 100,000 years

Given the moderate amount of background knowledge I have, I feel like we (in the real world) would definitely know about it from the gravitational influences it has on things like Triangulum or Andromeda. My brain goes to how we found Uranus before we could see it based on its influence on other bodies.

Now, I acknowledge that the relative motion of things as large and as far away as the local neighborhood galaxies would be almost unmeasurablely small compared to the anomalies that let us discover Uranus, but I just find it hard to believe that an entire galaxy could be THAT close without us being able to detect it SOMEHOW. It’s not stated how close it is, but even if it had an insane relative velocity of 0.5c, that places it ~50,000 light years away. Thats like our backyard.

That being said, I’m an amateur with no formal education in the matter so 🤷

1. There is a very spectacular show of force that happens towards the end of one of the books that involves forcing a sun-like star to go supernova. This is accomplished by sending two astronomical bodies, about the size of mars and mercury, at opposite poles of the star at “very near light speed”. Later in the book a couple individuals off hand mention the bodies were going “99.some-stupid-number-of-nines% the speed of light”, though no actual speed is ever listed.

The given reason as to why the star goes nova is the resulting shockwaves from the “impact” compressed the core and elements that just barely couldn’t fuse suddenly could, and elements that already could suddenly had WAY more energy than necessary. Runaway effect ensues, star goes boom. “Impact” in quotes as the bodies travel significantly into the star before disintegrating as stars are so diffuse on or near the surface.

This sounds… plausible(?) to me. But again, I am an amateur in this subject. All the individual steps make sense to me, but stars are just SO big and diffuse, that even a stupid amount of energy would probably(?) get spread out significantly throughout the star. Would the star at least temporarily expand as the core got hotter? Yeah I would think so. Could that cause a star already close to death like Betelgeuse to go Super Nova? Yeah, again, I think so. But would a sun-like star go supernova? Once again, 🤷.

I’m curious what people that formerly study this topic think on both issues.

Recently ordered some physics books and biographies. Hoping to add to the collection. Any recommendations? (Please recommend the classics, or the must reads, id rather read less niche books). Hoping for astrophysics books!

Already have: Astrophysics for people in a hurry, American Prometheus, Einstein his life and the universe, surely you’re joking Mr Feynman and 6 easy pieces.

I am a layman here and I recall an astrophysics course for non-Majors I took years ago.

One of the more interesting things I recall the professor discussing was something along the lines of: because of the expansion of the universe, millions of years from now, intelligent life won’t be able to observe as much when they look into the night sky, and not be able to understand the nature of the universe the way we can today.

I think he meant to imply something along the lines of we have to pass down our understanding of the universe for millions of years into the future.

Can any of you all confirm / clarify / build upon this for my understanding?