Matter Definition and 1000 Threads

I'm 31 years old & going to enter into 2nd year of BEng mech. Degree which has 3 years.I already have diploma in marine engineering & have sailed on ocen going ships for 1 year as junior engineer.Is the first is better? (1.Is 1 year experience on ships can relate to mechanical experience...

I am currently applying for Phd's for next year as I am a final year Mphys Physics student. I am only interested in theoretical physics (i know the risks). The problem is that I can't find any theoretical PhDs in particle physics where I would do research in Dark Matter. My question is whether...

https://www.sciencealert.com/matehmatical-model-of-cold-dark-matter-bose-einstein-condensate-stars Interesting read. Thoughts and comments?

Do you know if there is any theory/model where dark matter is considered as a gas? Bullet Cluster suggests that dark matter travels with visible matter and forms halos around galaxies, clusters, etc. It is possible to consider these halos as dark matter atmospheres of massive objects/structures?

let's imagine that we can create a black hole from dark matter. Is it going to be different from the ordinary black hole(which is created by ordinery matter)?

Hello, Currently studying electromagnetic radiation and ionisation and a bit stuck on a concept. From what I think I've understood, an electromagnetic photon enters matter, and if the energy is > 10eV it will displace an electron causing it to ionise (and therefore moving out of the atom). This...

I want to start by saying that I'm in no way trying to say that Dark Matter isn't a real pehonomenon in space. I also have no intention to sway one way or another. However, I feel like most scientiests are swaying towards the 'dark matter' is some kind of WIMP or such. It's much easier to read...

This is a topic I've mentioned a few times before. Essentially the structure of matter in quantum gauge field theories is unclear to me. I have no clear question here, just some initial discussion points. So at the first level, it seems a particle based view of quantum field theory is difficult...

I've been reading Feynman's (classical) derivation of the refractive index and I wonder if there is a more quantum mechanical description in terms of complex number field vectors - one vector for that part of light that goes straight through and another for that part of light that goes through...

If for any given segment of the sky there are twice as many elliptical galaxies as there are spiral galaxies and if light to mass ratio of these elliptical galaxies (M/LH ratio is about 1.8, independent of RE/R1/2). https://arxiv.org/pdf/1303.6896.pdf It would seem that 2/3 of the universe...

What happens to the kinetic energy when an object is disintegrated? Does it survive? For example, if I throw a baseball at the sun at 100 mph, I will get X amounts of heat energy released and X amount of light as it burned up before contact. If I threw another baseball 100,000 mph into the sun...

Hi, http://curious.astro.cornell.edu/about-us/101-the-universe/cosmology-and-the-big-bang/general-questions/570-where-did-the-matter-in-the-universe-come-from-intermediate The website given above says that the matter was created via pair production process (like electron anti-electron...

In a previous message I have tried to show that electrical systems exist which do not generate electromagnetic waves with appreciable energy even if such systems have parts in accelerated motion. Now I add a further example by which the meaning of what I tried to say becomes clearer. The problem...

I'm trying to figure out how to arrive at the final expression, as given in the lecture notes. I tried to work this out by myself but getting different figure and units. I've considered the followings, normalize the equation from its values e.g. spins and x parameter, as g~100, x~10(m/t~10)...

So I have a question regarding the Alcubierre metric and the phenomena of stars on outer edges of galaxies moving at higher velocities than their orbital calculations state they should. When taking the accelerating expansion of space into account due to dark energy, could a sub-luminal...

How certain are scientists that the solution to the dark matter problem is a new, unknown particle (or more)? Theories that eliminate the need for new particle(s) and suggest modifications to the current understanding of gravity seem to get less attention. Why is that?

h is plank constant and v is frequency. I was using this to derive the TDSE. But I ran into problem because to substitute k^2 in E=h^2/8mpi^2 * k^2, I can use single derivative of psi squared or double derivative, both of which tend to give the correct answer. So, is my assumption of energy...

I apologize for the fact that this information is 2nd hand but a very intelligent and reliable friend tells me that in “Dark Matter and the Dinosaurs” by Lisa Randall she hypothesizes a disk of dark matter, which she calls “Double-Disk Dark Matter (DDDM)” that is superimposed over the center of...

I am no basketball expert. I have never watched an entire basketball game in my life. However, several times in my life I have watched a few minutes of basketball games here and there enough so that I am familiar with the basics of the rules and objectives of each team in the sport of...

I understand that the evidence for dark matter, although indirect, is quite strong. Yet there are a few things that puzzle me about the dark matter idea. If dark matter is the predominant form of matter in the universe, why does it have no effect on solar system dynamics? The solar system is...

We have a Universe that can be seen by Hubble maximum and we can imagine millions time more than that but if there is no boundary, there may be another millions of universe. Suppose we gather this all millions of universe and say this is a giant universe of universes and thus matter do not stop...

The bulge of the milky way is 40 parsecs in radius. There is 288.218 stars per cubic light-year in the milky way bulge. At the density, spacetime for the entire 40 parsec radius should be severely distorted. The total stellar mass of the bulge is about 25 billion Solar masses. The Milky Way has...

I was searching for d Broglie's original Papper of matter waves, I didn't get any thing on internet, please anyone help on this?

First of all: excuse me for my not good english written language. I come to the question with an example. Let us suppose two electrons are in space with initial velocity equal to zero. Given the Coulomb force such electrons will be submitted to an equal and opposite accelerations (for the action...

Has the ratio of normal to dark matter remained the same since the beginning?

This is a theoretical question that may not be rooted in reality. I hope this was the right section. Please clear up all misunderstandings. Since dark matter can’t emit light, could it be possible that dark matter is ionized matter? I always thought you needed electrons to emit light. Then that...

I'm studying out of Classical Electrodynamics by Ohanian and in chapter 2 (Electrostatics) he makes the following claim while discussing the electric field: I'm a little confused by this, and I can't seem to find any sources that share this view. I'm even more confused because in the...

Regarding dark matter, is it possible that at the quantum level there is some unknown property to gravity that is making it appear that there is this dark matter attracting normal mass but it's actually just that on a galactic scale gravity acts different than GR predicts? Or is that completely...

The false vacuum of the inflationary universe is described as a 'peculiar state of matter'. We know that matter density in the big bang universe dilutes as ρM ∝ a-3. Is it possible to assign a dilution rate to the 'peculiar state of matter' of the false vacuum as well?

This paper: Bob Holdom, Jing Ren, and Chen Zhang. "Quark Matter May Not Be Strange." Physical Review Letters. DOI: 10.1103/PhysRevLett.120.222001 Proposes properties of elements further along the Periodic Table of elements - than the elements we have created so far. I cannot evaluate the...

I'm wondering what properties of Dark Matter are known for certain. Such as: How much does it collide with itself, and with ordinary matter? What does ##\sigma/m\le 7cm^2/g## mean (and why is the estimate rising in more recent studies)? How does it compare with ordinary matter, e.g. liquid...

I would like to hear what the opinions are. Could sterile neutrino's be dark matter? I'm sure this has been discussed if not here then somewhere.

Are strongly interacting dark matter quarks displaced by visible matter? Chiral Gravitational Waves and Baryon Superfluid Dark Matter We develop a unified model of darkgenesis and baryogenesis involving strongly interacting dark quarks

Does anyone know the speed of light in dark matter?

If dark matter is a supersolid that fills 'empty' space and is displaced by visible matter, then is this the same notion as the spacetime fabric having mass and being curved by visible matter?

Can massless particles form some kind of nanotube that can trap other particles giving the nanotube mass? Is this dark matter?

Before quantum mechanics, light was generally seen as a wave and matter as particles (biliards). From e.g. the discovery of the photoelectric effect, one saw that light can also be seen as a particle. From e.g. the double slit experiment, one makes the interpretation that matter can also be seen...

Homework Statement Consider the density perturbation smoothed with a Gaussian of scale ##\sigma##, ##\Delta_{\sigma}(\vec x') = \int d^3 \vec x \frac{e^{- \frac{(\vec x - \vec x')^2}{2 \sigma^2}}}{(2 \pi \sigma)^{3/2}} \Delta (\vec x)## Calculate the power spectrum ##P_{\Delta_{\sigma}}## of...

Thought experiment: single use of "magic" Setup: Let's assume we have a giant ball of water in space. Magic: Let's assume the water does not compress its center under its own gravity. (Constant density of 1 g/cm^3) Basic stuff: The mass of this ball of water, (since it does not compress)...

According to the article in Astronomy Magazine June 2018, the satellite galaxies of Centaurus A are rotating in the same direction in a relatively thin plane, vs randomly distributed if there is a dark matter halo/sphere surrounding large galaxies. Any thoughts on this new finding? I've only...

From an outsiders view, it appears that the old shell theorem is relevant to the dark matter issue: If one views a spherical cluster of galaxies as an interconnected structure, gravity would increase linearly with distance from the center and be greatest at the edge of the cluster. For a spiral...

No I'm not a particularly big person with a weight issue. Somebody asked me this question and I don't know the answer, but somebody here will. OK, it's now accepted that dark matter is everywhere in the Universe, it tends to clump with regular matter because all matter is subject to gravity...

How well is the transition between energy and mass understood? Energy can turn into matter and matter can turn into energy but what is actually happening between the two states? Imagining that matter just simply appears and disappears under an infinitesimal amount of time feels weird to me.

1) Is acceleration relative? 2) Can an observer in an accelerating body assume that he's at rest and everything else is accelerating except him and the object he's on? 3)Earth is accelerating and decelerating in its orbit around the sun all the time and yet we don't feel it, why? Is it only...

I read that atoms transition from electronically excited to vibrationally excited. But how?

im curious as this question came up in a chemistry forum and it's more of a physics question I believe . State changes between elements of near similar number , what constitutes the extreme phase changes ? It was answered that there is no real answer for why the phase differences occurs at...

Homework Statement I don`t know if the image will show so I`m also adding a link to the image of the problem. This problem is a modification my professor made to the one in the link below(*), he changed the rigid diathermic partition into a movable partition. I`m supposed to find the...

Hello everyone, "Does a charged particle radiate in free-fall?". I read many threads on this subject and I was surprised to find out that there is no unanimous "Yes or No" answer to this question. Here is an interesting answer from researchgate.net: The question is widely discussed in the...

My question to you is this... Can the interior of the Sun be described as an ideal gas? From my knowledge, to describe a body of gas as an ideal gas, the separation between the particles must be much greater than the size of the actual particles. How could one justify whether the Sun fits this?

Why is the density of matter greater near the galactic center?