Matter Definition and 1000 Threads

The speed of star on the outer of are solar system is not according to the visible mass. Change the law of gravitation F = 1/r^2 to fix this. Galaxies far away are moving away with increasing speed. Change the law of gravitation F = 1/r^2 to fix this, include a repulsive force to fix. Would this...

I understand that the Big Bang was an explosion from an extremely tiny mass with particles and quanta traveling away into empty space (anything out there at the instant of this bang being too far to hit yet). I also understand that some ejecta from the Big Bang have been colliding since then...

https://phys.org/news/2018-04-dark-interactive.html "Observations using the Hubble Space Telescope appeared to show that a galaxy in the Abell 3827 cluster - approximately 1.3 billion light years from Earth - had become separated from the dark matter surrounding it. Such an offset is predicted...

What is the shape of a typical dark matter halo around a galaxy? Does it orbit a galaxy like visible matter? It is said that dark matter does not lose angular momentum, necessary for compactification. How then does visible matter lose angular momentum?

How does the Singularity produce all of the diverse matter and properties that we observe in the Universe today? Although Theories like Quantum Gravity have somewhat produced indications about the existence of Graviton particles and allow some form of Gravity to operate within the laws of...

hi guys i was thinking about the inner product we choose in quantum mechanics to map the elements inside the hilbert space to real number which is given by : $$\int^{∞}_{-∞}\psi^{*}\psi\;dV$$ or in some cases we might introduce a weight function dependent on the wave functions i have , it seems...

I have my MSc in 'Computational condensed matter physics'. I used VASP package for simulation during my MSc. and i am also well experienced in FORTRAN programming language. Can anyone give me short note about 'PhD in computational physics'? so that can continue my PhD in 'Computational Physics'.

Dear all, We learn students to work with significant figures. I guess we all know those rules of thumb. Now imagine I have an expression like L = 2x, where x is a length a the 2 is an amount, i.e. the value of a discrete 'function'. If x=0,72 m (2 significant figures), then L = 1,44 --> 1,4 (2...

At the end of the inflation period (if it occurred) the potential energy of the inflaton field decays into particle/antiparticle pairs. When a particle/antiparticle pair is created each component of the total 4-momentum of the pair is zero. This must include the time component as well as the...

Two Recent Papers Propose A Simply Tweak To How General Relativity (GR) Is Applied That Purports To Explain All Dark Matter Phenomena Motivated By A Version of GR and Quantum Gravity. The pair of related papers with overlapping text and common authorship (cited below) were published after peer...

I think in solid or liquid phase, there are many molecule having a very large speed due to random character in moving.So the liquid or solid matter must co-exist with other phase because some molecules escape from surface of solid or liquid matter.Then is there any condition for existing only...

Hi, forgot to say a thanks for all the info provided in my previous thread to everyone who posted. So what is the answer or answers to this threads question or what works?

Neglecting the air resistance, is it more difficult for a biker with a proper gearing in his bike, to increase his speed by 5 kph if his current speed is 20 kph rather then if his speed is 10 kph? It seems that the answer is yes according to the energy formula but I've asked several bikers and...

Prof Wetterich has proposed that atoms are shrinking rather than the Universe is expanding. Here is a 2013 Nature News article describing his theory: https://www.nature.com/news/cosmologist-claims-universe-may-not-be-expanding-1.13379 Here is his 2013 paper "A Universe without expansion"...

I read somewhere "space was not completely homogenous (the same at every point). Instead, some areas were denser and hotter than others, and these dense regions could have collapsed into black holes." and I was wondering what does it exactly means? Did space itself fall into becoming PBHs...

When I think of a wave propagating through space I think of a geometric wave-like structure propagating through the matter in the surrounding environment. If someone yells and you hear their voice is it actual matter that is emitted and that your ears pick up on? If this were the case there...

In the other thread, it was noted that dark matter doesn't interact with ordinary matter. Now I tread cautiously, not knowing any of the relevant theory. In some school questions, I've come across discussion of 'dark matter halos' which are necessary to ensure the rotation curve of the galaxy...

Given the fact that our galaxy consists mostly of dark matter (accounting for roughly 70% of its mass) we know astonishingly little about the stuff. Admittedly, if I could give you a lump of dark matter, you would propably be totally underwhelmed by the "experience". First of all, you wouldn't...

I heard somewhere that light in the visible spectrum that we see interacts with matter the most? Is that true, and in what ways?

Recent Science headlines are abuzz about a new theory. Physicists claim information is the fifth state of matter. By 2245, half of Earth’s mass could be converted to digital bits https://www.zmescience.com/science/news-science/information-fifth-state-matter-0252/ Digital Information Threatens...

I am looking for introductions and reviews (papers or books) on the possible observation and the nature of dark matter. This book seems to be a good start, but I would be grateful for any other recommendations that are accessible to people with knowledge of physics at the undergraduate level...

Although we don't have any other Universes to compare ours against, we generally accept that there is a large amount of matter in the Universe. At the point of the Big Bang, what determined how much matter the Universe would contain? Would it have been equally probable, for example, for the...

Hello, The periodic table contains 118 different elements which compose regular matter and the reality around us. On the other hand, "antimatter" is made of elements not included in the periodic table. As far as the periodic table, I think about 98 elements occur naturally while the other ones...

I understand black matter surrounds galaxies and galaxy clusters, but is it inside the galaxies themselves? Is it in interstellar space? If so, does it surround the sun and planets, and if so, could it be right here on Earth with us?

Press release arXiv ~3.5 sigma significance and it could be caused by tritium contamination - although it's unclear where the tritium would come from. If it is really new physics then solar axions or a magnetic moment of neutrinos would fit well. The key plot, figure 5 in the arXiv version...

It's a simple question, and I feel like the order in which you run two loops would not matter in regards to how long it would take to run the script. You'd still have to run through ##m \cdot n## cells no matter the order. If you check column-wise, you will have to check all m entries in each of...

Hello, Apart from the graviton postulate, which would permit such a mechanism, my question is: would a similar mechanism be possible with a stationary wave? (the simplest scenario I can immagine is of two opposing waves). My background is in DSP and Acoustics so I might get things wrong (a...

I was having a discussion with someone, regarding whether Time Travel was possible. The opposing individual argued that people are composed of matter that is simply woven into the fabric of space-time, therefore, rendering us unable to travel through time. I wasn't sure if he was right because I...

"Half the universe’s ordinary matter was missing — and may have been found" The long-sought matter appears to have been hiding in the gaps between galaxieshttps://www.sciencenews.org/article/universe-missing-matter-found-fast-radio-bursts

So far as I understand it, a photon can split up and create particles with matter, even though the photon is massless, yes? So if a photon can be more places at the same time, it should be able to create multiple particles all at once? So how is this not Dark Matter?

My friend gave me some statements which are wrong, but I could not tell why they are wrong. He wrote, Since ##\omega = \frac E \hbar = \frac {\hbar k^2} {2m} = k v##, then##p=\hbar k =2mv##. I guess that ##E =\hbar \omega## may only appied to photons, not matter waves. Is that correct?

Neil deGrasse Tyson states that "dark matter exerts gravity according to the same rules that ordinary matters follows" How do we know this? If we have no idea what dark matter is, how can we say how it behaves? How do we know that a single "molecule" of the stuff doesn't weigh as much as the...

What books are recommended for a course in condensed matter physics at a graduate level?

Can someone simply explain to me what are the time crystals? What are they built from (matter, do they have mass)? I cannot find a clear explanation of them. I just know that ordinary crystals are 3d, time crystals - 4d.

I'm working on a PhD in condensed matter computational physics, particularly with method development. My plan is to go into industry afterwards, and out of curiosity I've been looking at job listings. It doesn't look good to be honest. Listings for physicists mainly require some type of lab...

Hey guys. I have offers to do summer research at both Brown University and University of Chicago this summer, and I was wondering which school has a stronger department in regards to condensed matter theory. Personally, I think it's University of Chicago, but I'm not too sure and I'd appreciate...

My question comes from the following confusing aspect of the big bang theory. Since at different stages during development of the current universe, we know that fundamental particles, atoms and large masses started to form. And if all large masses are embedded in spacetime when during the...

Thoughts? Guessing it’s speculative, but is it a reasonable, testable candidate? https://scitechdaily.com/sub-atomic-particle-identified-that-could-have-formed-dark-matter/

In your opinion, what are the main challenges for future condensed matter physics? What type of material systems are more desirable to discover? Which quantum properties are the most interesting to demonstrate for future devices working at room temperature and ambient pressure (besides...

https://www.sciencedirect.com/science/article/pii/S0370269320301040#br0210 I need to give this more thought, but the ballistics section is pretty good, and I think their basic dE/dx argument is sound: If a collision at a ballistic rate transfers about the same kinetic energy to the human body...

If there is dark matter that doesn't gravitate, do you still call it dark matter? Hossenfelder mentioned General Relativity can't be entirely correct because of quantum gravity, so this gives the possibility of dark matter that doesn't gravitate...

Resources I have looked at distinguish between the three basic states of matter in terms of how closely particles are held together; i.e. in solids they are bound most closely, in liquids less so and in gases they're much freer. Would it not be more correct to refer to how closely atoms or...

Hi Guys. I have a question about General Relativity. If, according to GR, Mass curves Spacetime and gravity is simply matter falling into that curveture, why does all matter fall equally regardless to their spatial position on the mass. For example, why do people in let's say Australia fall into...

Probably a silly question I thought of last night but would appreciate some clarification. Matter falling towards a black hole joins the disk spinning around the black hole slowly inching towards the event horizon with each orbit of the black hole. When matter passes the event horizon does it...

Is there any astronomical indication that gravitational force between dark matter might be weaker than between visible matter?

Does anti-matter and matter annihilate each other even if they are not same "type" (eg. neutron and positron) and they meet each other?

If I understood well, cosmology makes a difference between matter moving in spacetime and the expansion of spacetime itself. Are these concepts experimentally distinguishable, or this distinction is only in our theories?

As I understand it, as you get closer to a black hole no matter what trajectory you were on approaching it, you will get pulled into the disk of spinning matter around the black hole which I assume is around it's equator? I am just curious as to what is happening to the "space" in the disk, and...

Dark matter is distributed in halos around visible galaxies, while baryon matter is distributed in spiral-shaped visible galaxies. Where does this difference come from?

Well, I don't understand the integral part of ##1/(VD) = \int_0^{\hbar \omega_D}\frac{\tanh(\beta E/2}{E}dE## and ##\tanh(\beta E/2) \approx 1-2\exp(-\beta E)##, then he writes the following (which I don't understand how did he get it): $$\frac{1}{VD} = \sinh^{-1} (\hbar \omega/\Delta(0)) =...