There should be at least two major theories; MOND (Modified Newtonian Gravity) and dark matter. The reason dark matter theories are currently regarded as the better theory is because of MOND can not explain e.g. bullet cluster (predictions are wrong), whereas dark matter can. Mind you, dark...
Hi!
I'm a first year MPhil student starting my project on black hole growth and dark matter annihilation. I have been struggling with some fundamental things such as getting connected. I would like to be able to discuss my work with people but I am not really sure where to start.
Hi,
Thanks a lot for all the replies. I'm sorry I didn't reply earlier.
@micromass
That's actually a very unexpected reply, and I tend to agree with you. I self-study quite a lot, so in some sense I was hoping that the best proposed method would involve working things out by yourself. I don't...
I'm especially curious if there are any people who actually start off with Sage/Mathematica, e.g. they want to solve a problem and they open up Mathematica and start working on it right off the bat without first formulating the problem on pen and paper.
Hi!
I'd like to discuss your experiences with pen and paper vs software. Especially young people are welcome to join the discussion :)
I'm wondering if there are people who do *most* of the symbolic calculations on a computer. I am very familiar with pen and paper and I've been wondering...
I have come across a serious problem in my studies. I like to self-study, but I am wrestling between different study methods.
I have at least three options on how to read material:
Read through it
Derive every formula yourself (~6x extra time)
Read the title and outline, and re-invent the...
There are a lot of Q&A about research in physics here. I'd like to know more about examples of your own career path. Did you change your subject, how did it work out? Did you do work mostly independently, and if so, when did you start? How did you pick your school?
I'm a 23 years old physics...
Active vs passive learning:
There is research that people tend not to learn much by re-reading a book/chapter etc. On the other hand, solving problems tends to be useful for learning.
This made me wonder, is there research into passive learning by going through various different sources...
Hey, I'm sorry to revive a dead topic, but does anyone have experience with SageManifolds (http://sagemanifolds.obspm.fr/)? I would especially appreciate a comparison of SageManifolds to Mathematica. I am considering whether I should use free software or simply buy Mathematica.
The reason I...
Now that the conversation is starting to go into an interesting direction, does anyone know of tested methods to contribute the work evenly to a group? E.g. keeping meetings based on the effort done or something similar?
Does anyone happen to know a website where you can start a discussion with e.g. your colleagues about a very wide, unspecified topic or personal topic (e.g. research proposal which has not yet been decided), but which could still be documented and viewed publicly?
I hope I am posting in the...
Hey, thanks a lot for the helpful post. I really appreciate it! I particularly liked the fact that you pointed out that a strong student may dominate the activity. I remember that when I was studying in a group doing experiments we also encountered a a similar problem; one student was...
Thanks Chronos.
Yes, I mean CERN. What do you mean by macroscopic neutron star sized experiments?
I'm sure you can dig something up.
Cheers. The truth is that there are also many theorists out there making very strange theories without any predictions or backup from observations. Some even...
Thank you for your answer Drakkith. I was referring to the process of building further while testing. One can evaluate the pay-off of building and testing a model. This pay-off can be huge, minimal, or somewhere in-between.
Perhaps I can elaborate; I would like to know if putting much effort...
Dark matter particle candidates are being searched at CERN and the various dark matter models are being probed by cosmological simulations. The usual way to probe models via cosmology is to plug a candidate into a cosmological simulation and then compare the results with observations. Yet...
Thank you for your reply e.bar.goum. May I ask how closely you are working together? When you say group-work is a part of your work, do you mean that you share your results in weekly meetings, daily, in coffee tables, or do you mean actually sitting next to someone working on the exact same thing?
I would like to start a discussion about group work both in education and in work-life.
Group work, especially in smaller groups, tends to be 'active learning'. Active learning tends to be more efficient than passive learning. I would like to know if you as a teacher like to assign group work...
Thank you for the answers; learning by writing your own articles and by probing the lecturer are definitely viable methods of learning. I agree that reading articles is unavoidable; I would like to discuss methods to teach students to learn from publications independently. It's something every...
I will be working as an assistant for the first time in my life soon. I wanted to ask your opinions on teaching people to learn from physics journals.
When I started doing real research, I think the first problem I came across was that reading journals is hard, and learning from them is even...
Thank you for your replies. I have one interesting subject which is fairly specific (active galactic nuclei), so as suggested by e.bar.goum I'll ask my supervisor what he thinks of it. I'll also try to outline generally my interest in plasma physics just in case he has some other ideas. I've...
I'm currently a graduate student in Finland and I'll be moving abroad to study for an MPhil degree. I have knowledge of space plasma physics and computational physics, since I have worked in that field, and some basic knowledge of cosmology. I wanted to ask for advice on how smart it is for one...
I guess another interesting question would be what it would imply if we events propagating faster than the speed of light locally. Particles with negative mass? Tachyons? :)
I'm interested in the derivation of relativistic Boltzmann equation from entropy after reading Scott Dodelson's wonderful cosmology book. Does anyone know of any good readings for this?
The usual way of doing things in classical mechanics is to assume \frac{dN}{dt}= 0 and go from there; but...
Hey all and thanks for all the replies.
We used the Uintah framework for doing our simulations. In the end, we decided to make DM-only simulation on local scale, simulating the formation of a dark matter halo and comparing its distribution with the Navarro–Frenk–White profile. The test set-up...
Hey,
I'm trying to look for a single test set-up for a dark matter-only simulation I and my friend are building. It's currently based on a particle-in-cell approach and we are calculating the Poisson equation and particle trajectories in a co-moving frame (so expansion of the Universe is taken...
One can construct a model which blows up after any finite time-scale (whether this is physical or not is another question).
I should clarify further; I am not interested in solving this question myself (that means I'm not interested in coming up with the time-scales and constraints from...
I should clarify; I mean stable solution for galaxies on short time-scales and whichever structures remain stable if left alone (the bare-bone idea).
In short, I'd like to read about research with heavy emphasis on creating a "minimum constraint" model with constraints directly from...
Hey,
I've a short question. Is there any research attempting to constrain models of dark matter by assuming stable solution for the universe? I'm interested in knowing whether this gives any sensible constraints on the dark matter models.
I'm still fairly new to studying dark matter but as I...
Picture:
http://img263.imageshack.us/img263/7361/ongelma.jpg [Broken]
Homework Statement
Solve the potential energy of a charged sphere-shaped metal shell. What happens when you place a smaller, grounded sphere-shaped metal shell inside of that shell? What is the potential energy then? How...