Matter Definition and 1000 Threads

Can someone explain the disappearance of 57% of dark matter since the Big Bang? Is dark energy eating dark matter?

I have considered the possibility that dark matter is so hard to find because it exists in extra dimensions. Before posting here I googled this, and found that some scientists postulate this exact possibility, while others consider that extra dimensions themselves cause the effects that are...

I am a bit frustrated with my current job search and I was wondering if people at PF could give some guidance. I am a doctoral graduate in Electrical Engineering from a low ranked university (~ 180 US News overall ranking). Although a EE doctorate most of my work was in materials...

So I'm looking to find the distance light has traveled since matter - dark energy equivalence. Assume dark energy dominance from equivalence. Space-time has flat geometry and Ω0m = 0.315 , Ω0 = 1 Thus: Ω0Λ will equal Ω0 - Ω0m= 0.685 ρ0m (1 + zeq)3 = ρ0Λ where: ρ0m = ρ0c * Ω0m and: ρ0Λ =...

I have been wondering about how the universe created itself from nothing and it seems in spacetime, the time dimension must have come first followed by multidimensional space. Following this, matter and dark matter must have been created. While matter and dark matter both underwent timelike...

Ok, silly question. Lexx is a sci-fi TV show that ran from 1997-2002. In one episode they used 'approximately 14.2 Quadrillion Quadrillion drones" to basically suck matter away from the star slowly using gravity. Ive always wondered: Do you think this is possible? Or would such a large mass...

I'm trying to understand the concepts of physics, but there's one thing I don't fully get... If there is some matter with a spatial and temporal coordinate, let's say coordinate X, is the matter "in" that time and place, or "is" the matter that time and place? In other words, does space-time...

I know MACHOS and WIMPs are leading candidates for Dark Matter, but is there any convincing evidence to support them?

1. A sealed container of volume 0.1m^3 holds 3.0x10^24 atoms of helium gas at equilibrium. Distribution of speed of the helium atom shows a peak at 1100ms^-1. i) calculate temperature and pressure of the helium gas. ii) what is the average kinetic energy of the helium atoms? iii) what is the...

Is there any state of matter for fire or electricity ? If yes, then what is the state of matter ?

as to manipulate its possition?

Could a field of a certain.type of magnatism effect a giving area of salt water as to.either align or dispurse the water to more freely flow among them or slide between them .like a horizon of water molecules

Hey Everyone, Would appreciate any advice or suggestions. I know that I do not have many "safeties", but that is because I am applying to a bunch of master's programs (not physics /because of research interest) Physics GPA: 3.5ish ( No grade lower than a B... lots of advanced courses!)...

Greetings, I am interested in creating a thread dedicated to the discussion of the uses of currently discovered and used and theorized/dreamed of types of matter in our universe. This includes R.E.E's (Rare Earth elements, like Neodymium or Yttrium...

I have been researching energy to matter conversion experiments, and the only information that i have been able to find of a successful experiment is from 1997, when the University of Rochester was able to make a terawatt glass laser send photons into a stream of energized electrons from the...

I am just very curious if anybody could help me figure out which dimensions actually entail energy and matter axis. Also since colors are absorbed are there residual colour energies if so is there a known half-life? Any feedback would be greatly appreciated, thank you.

With http://xxx.lanl.gov/pdf/0705.4298v2.pdf and http://arxiv.org/pdf/1410.2236.pdf I have found some interesting information that there is a lot of empirical evidence to exclude a lot of CDM candidates. All what is necessary is some cross section for interaction with standard matter and the...

I understand that every chemical reaction has a mass defect - albeit it is very, very, very, very small, to the point we simply assume Law of Conservation of Mass. Nuclear reactions have a more sizable mass defect, hence the very high amounts of energy released. However, suppose some...

What are some ways that people are applying condensed matter physics/ soft matter physics to optimize some treatments in medicine, e.g. in magnetic hypothermia?

What are some exciting research areas in condensed matter physics at the moment?

I am wondering whether graduate schools really care about final semester course load. I am a senior physics major, applying to graduate schools in geophysics. Currently I am enrolled in the normal 16hr course load but am considering dropping down to 12 hours for my final semester. I've never...

How would you approximately describe matter in the core of underlying neutron star? I am asking for really fundamental properties. No strange matter, consider just n,e,p. A ratio, can we describe particles as free? Gas x fluid x superfluid? etc.

Homework Statement Could someone please let me know if this is correct? I'm unsure about matter always being conserved, does it change whether we're talking about Newtonian physics or special relativity? To me, matter is conserved regardless but maybe there is something I don't know...

Hi everyone, I know that classical mechanics and electromagnetism show that the electron is bound to fall on the nucleus. I want to estimate the duration of the phenomenon. I found the classical energy : E=-K/r and I'm able to compute the raying loss thanks to electromagnetism. But I am...

If possible, I would like an explanation that uses light as an electromagnetic wave, rather than a massless particle, because I don't understand photons. Thank you.

Hi guys, I know that if we consider a basic atomic model ( not considering quantum mechanics here) that an atom is mostly empty space ( 99.99999%) or something like that. But how about the space between the atoms? Would it be appropriate to tell middle school students...8th graders... that...

As I understand "Dark Matter" is an _assumption_ of existence of matter in certain space, to explain gravitational effects on the matter around that space. But when it comes to "Dark Energy" it is another assumption to explain why universe is expanding. But by Einstein's theory, mass and energy...

Good afternoon, I am trying to simulate the propagation of electrons in copper. To do so, I fill a Landau distribution with mean the most probable value of energy loss. However, my formula doesn't seem to work as I find that I can have higher energy loss than the electron energy itself! Could...

I know that the electrons around atoms repel the other electrons around atoms and the electrons never touch. But I believe that neutrons are considered ionising radiation correct? That means that they bump into electrons and knock them away from its nucleus. How does a neutron affect the...

It seems like most sci-fi hasn't really touched much upon dark matter. Instead of making up all sorts of fantastical new dimensions or universes, why not focus on dark matter, something we legitimately don't understand and really exists? There's far more dark matter than baryonic matter. Is it...

I would love some suggestions about my undergraduate research, thought it may be improper to ask here. I apology if I break the group rules. My undergraduate research topic is dark matter. My plan so far is to study important observations before making other progress. I have found an...

whats an array for?...whats a vector for? what do they do? what purpose do they serve?

I saw an interesting article on dark matter possibly explained by axions and wondered what others thought of this? http://io9.com/curious-signal-could-be-dark-matter-pouring-from-the-su-1647581644

It is unclear to me (1) what precisely diffeomorphism means and (2) what happens when all matter is removed from the spacetime. Sean Carrol says that: "the theory is free of "prior geometry" and there is no preferred coordinate system for spacetime." http://arxiv.org/pdf/gr-qc/9712019v1.pdf page...

Homework Statement During fusion of hydrogen to helium, 4 billion kg of matter are converted to energy each second. What fraction of the Sun’s total mass is lost each year to this process? Homework Equations None. The Attempt at a Solution First: Convert how many seconds are there in a year 1...

We read that the a couple is a free vector, i.e it does not depend on the point of application. However, please consider the following example: If you apply two equal magnitude forces anti-parallel to each other, one on each side of the wheel, a couple is formed, and so the wheel will rotate...

I have always been very indecisive about what I want to major in. There are so many different things that have interested me over the years. I thought I had settled on a career plan in the astronomy and astrophysics field, but then I began to research and learn about how difficult it is to get a...

The question was : describe the first law of thermodynamics. I said matter can't be created or destroyed. I got marked wrong, my argument will be that the laws of thermodynamics can be written in different ways. Einstein famous equation relates matter and energy. There is also the matter-energy...

I have decided to grow a plant that could possibly help with my illness. This plant could possibly cause an issue due to its nature. Is there an acid that is somewhat safe to dissolve dried plant material quickly? I have looked at other physics forums that talk about piranha acid and that is WAY...

In my studies, I find myself coming back to the same question.How do we know all these things about matter. Its quantized, it has mass and, charge and blah blah blah. I understand that these models of the building blocks of "physical things" are well tested mathematical models that attempt to...

The objective of this post is to: (i) generate a discussion of whether results of the double-slit experiment address solely the nature of matter, or do the results also address the nature of probability; and (ii) to determine if there have been any comparably structured experiments outside of...

Greetings PF! I am in good mood, and I wish you were as well. Everything has been going well since the beginning of the semester: I've been doing well in the three core courses so far, and I am also about to get into research soon hopefully; but not in my initial interest of particle, but in...

Note: this is a re-post because my initial post had problems, no one could reply to it. Ok this is my second in the series about dark matter. In a previous thread I asked where is dark matter https://www.physicsforums.com/threads/where-on-earth-is-dark-matter.764693/ The main response to my...

Dear all, In one of his lectures,Prof. Susskind mentioned that the event horizon "bulges" forward to meet any incoming radiation or matter; and it is a property of Einstein field equations. I have not come across any such property, and if it exists, shouldn't it belong to the Schwarzschild(or...

In my physics lecture, my professor "proved" that acceleration does not affect the amount of energy used in driving a car. Assume car is driven along flat road. In the short, (assume air resistance is neglected, and the W done by the car's engine, W_{engine} is non conservative, \Delta PE...

I'm a beginner in quantum optics. I always become confusing when the material's refractive index is complex. This time is about the photonic density of states. We know that if the material is not absorbing or dissipative, meaning the refractive index is a real number, the local photonic density...

What theories attempt to explain the dark matter today? The force of gravity is the only thing that interacts with dark matter, the fundamental force "weaker" is gravity however, if she is not weak just reach dimensions that do not have access, dark matter could not be these heavenly bodies...

Dear Friends! I have read that in early universe in the inflationary phase the average density of matter was equal to critical density and now it is 10 percent of that due to which it is probably inferred that there must be hidden dark matter. Please correct the information if wrong or...

I got a question in my mind as to how the tiny dot of matter during the big bang contained so much energy that could create the universe. Remember this tiny dot contained so much energy that it could transform this energy into matter in the form of the universe (Remember E=MC2). The Quantum...

One of the sources of matter creation is pair production when 2 gamma ray photons collide and produce electron positron pair. The other would be Quantum Fluctuations which create again electron-positron pairs. What are the other methods of matter creation other than the above two?