Matter Definition and 1000 Threads

Im doing a group presentation in one of my astrophysics papers this semester, and my part of the presentation is to research and outline the various theories for what dark matter could be. Does anyone on the pf know of any sites they may think will be helpful in my research, or any ideas on...

Hi, I'm currently in my last year of undergrad and I'm wondering about which specialization I should pursue. I'm looking for career stability, I don't mind leaving academia I'd just like to employ what I study in school in my future career. So, to my questions 1) In terms of career stability...

Hello, How much volume or mass of space does one need to see appreciable effects of dark matter where general relatively seems to break down? What is the critical volume of space at this time where people can see the effects of dark matter and where they cannot? Is there a spatial scale smaller...

Hello, My question is, how much dark matter (any of mass, volume, density, etc) would we have to have in our solar system for us to detect it? My guess is that we would detect the dark matter through gravitational lensing or the perturbation of planetary orbits. On previous posts about dark...

Can we consider temperature in general as "property" without even been associated to well defined states of matter. Like the boiling and melting points.

I am wondering if there is some type of matter in the core of the Black Hole. Is it possible to compute the distance from the surface of the Black Hole Core to the Event Horizon? Oh that would be fun to calculate.

I started this thread because I was much confused by the post https://www.physicsforums.com/threads/first-energy-or-mass.923809/page-2#post-5831139 in a thread which was closed before I could seek clarification there. I am hopeful that @PeterDonis, and/or others, will help me here. Peter...

If we equate Planck expression ##E = h \nu## with Einstein's ##E = m_o c^2## we get $$m_o c^2 = h \nu$$ what can we conclude from this? Since the frequency ##\nu## above is directly related to the frequency of which a particle will be found at a given point, would the above expr mean that if...

Wikipedia dixit: The standard model of cosmology indicates that the total mass–energy of the universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy ******************************************************************************* According to this, dark matter must be...

Are there variations of dark matter concentration on Earth based on months or seasons of the year?

Now from my basic understanding of particle physics, matter is supposed to be fermions, while particles involved in force interactions are bosons (photons, gluons, W/Z, and Higgs). Now, apparently there are also some composite particles of matter that are considered to be bosons too. For...

Antimatter and matter cancel each other out. What does this mean? Do the particles just cease to exist? Does this go against the law of the conservation of energy? HELP

Homework Statement A 125g pear is immersed at the bottoming of a beaker of water which is filled with 500cm3 of water. Salt of mass 30g was then completely dissolved in the water before the pear begins to float (assume no change In Volume of the water ) given the density of pure water is 1 g...

Erebon theory is a novel explanation of dark matter recently invented by Roger Penrose. Erebons are scalar particles of the order of a Planck mass which can only interact gravitationally. When erebons decay, they release their energy as oscillating classical gravitational waves on the order of...

My physics teacher, who dislikes the idea of dark matter, told me that a physicist created an alternative explanation to the phenomena caused by dark matter. Is there something I missed on the news? What is the alternative theory to dark matter and how does it explain 'things' ?

I've been reading several ideas postulated by some researchers using either Dark Matter and or a micro Black Hole as energy sources to power a future spacecraft . 1) using dark matter as fuel to power a spacecraft by taking dark matter into a cavity and shrinking it to critical point using...

Hi all, This is probably a newbie question - I'm a non-physicist but I did do some physics at university. My question is, during fission, when matter is converted into energy, what is the matter/particle that is actually converted into this energy? I would imagine that the particle(s)...

I know that Quark-gluon plasma is the hotter state of matter that we know. Soo is solid the coldest state of matter ? If there is no so sorry for my stupid brain!

Dark energy is still energy so couldn't it also gravitate? The question is how large of a region of space must there be before dark energy could sustain itself at a higher density through self-gravitation? I'm under the impression that dark matter works at a smaller scale than dark energy. Or do...

Time is neither matter nor energy then why it is influenced by Gravity?

As I have come to understand it - we have no current means of directly interacting with Dark Matter. We can only observe the gravitational effects that Dark Matter has on Baryonic Matter. My question is: What forms of detection have been attempted and determined to not directly interaction...

Edit by Moderator: Unacceptable source deleted. Why the central problem in neuroscience is mirrored in physics. 'Physics tells us that matter is made of particles and fields, which have properties such as mass, charge, and spin. Physics may not yet have discovered all the fundamental properties...

Without knowing whether WIMPs or axions or something else are what dark matter is composed of, can we speculate about the vacuum density creating only normal matter, and by what mechanism?

While the subject has been talked about to death by many a researcher, who will discover the first dark matter scientific paper that will prove beyond theory that describes it in detail. The real discoverer will undoubtedly be the hero of physics, astrophysics, and cosmology and be awarded...

Homework Statement Consider the Earth as 1. with a constant density of matter, 2. as a thin shell empty sphere and 3. with a constant linear density of matter ##\rho(r) = \rho_{0}r##. In all cases, calculate the gravitational potential and the gravitational field everywhere and make a...

I'm currently working in condensed matter theory. Looking at other fields of physics, it seems easy to relate them to a lay audience; for example, in explaining why you study physics, a high energy physicist could go on about the 4 fundamental forces and searches for a unifying theory of...

Reading some of the recent info on black holes and how they ingest gas matter including stellar material... why doesn't dark matter be absorbed into the black hole and according to the article dark matter is part of black hole formation...

If space is expanding and at the same time speeding up, something must be driving it. It also appears to be self perpetuating, as something cannot continue to expand, speed up and backfill at the same time? Could the driving force be dark matter/energy?

How much tension between recent AMS-02 80 Gev dark matter and Lux-Xenon negative results? Recent results ( Arxiv 1610.03840 and 1704.08258) suggest a WIMP dark matter particle near 80 Gev. See also https://phys.org/news/2017-05-possibility-cosmic-rays-due-dark.html If this particle really...

From Wikipedia: So, assuming we have a massive ball of water that keeps growing, but somehow manages to remain at a fixed density, the moment the Schwarzschild radius overtakes the physical radius, will the gravitational properties of the ball of water undergo a sudden, dramatic change?

Is dark matter physics considered a low or high energy physics, and why?

i know that every thing has mass (dont know why if you can pleas explain it for me too) so can i remove mass from matter but still have it form

The spacecraft "Helios 2" (with 100 kg of mass) used the Sun to get a speed of 250.000 km/h using gravitational assistance, I want to know if the mass of the spacecraft influences the result of the speed. I mean, if the spacecraft mass 10.000 tons, the speed would be less of more?

The ADM formalism gives a definition for the energy (Hamiltonian) of a static, asymptotically flat spacetime. This energy can be equated to the mass of the matter (for example, a black hole) which resides in this spacetime...

Why is it that dark matter does not inhabit gas clouds, I would have thought that thees gas clouds will some day become a galaxy, so why no Dark Matter?

Hello, I've been reading articles about the OGLE micro-lensing project, which started out looking to find dark matter as 'massive compact objects,' but now seems to have had more success finding exoplanets. Searching the forums here I couldn't find much recent discussion about theories of this...

I recall reading somewhere (I can't remember where) that there is astronomical evidence that dark matter has different densities in different parts of the relatively near parts of the observable universe. Q1. Is this correct? If so, can someone please post a link to a relevant article? The...

Dark Matter was never found, what Modified Gravity theories should we check now?

i have been to two schools the first a community college and now in a university and i may transfer to a third one, for family reasons, will this matter to graduate school? that I've attended three universities instead of one?

Does the weight of a car or length of gears it has change the requirements for clutch strength or is the requirement solely dependent on the torque the engine applies to it? I see a lot of consensus that says the former, but I think it is the latter. An engine making 300 lb-ft should need a...

https://www.sciencedaily.com/releases/2016/12/161219085020.htm http://www.skyandtelescope.com/astronomy-news/no-dark-matter-from-lux-experiment/ I believe that WIMP theory has been the leading contender for dark matter in the past, but the null results from LUX, PandaX, Fermi and LHC would all...

Nobel laureate Alexei Abrikosov, a condensed matter theorist, passed away yesterday. I have no additional information at this time.

I am currently studying Faraday's law and electromagnets and in class we were told that if you had a coil and say a bar magnet was passed through it the faster the magnetic field was applied to the coil the greater the induced voltage or emf would be. I do not understand why the speed would...

Hello, I have been reading about how Dark Matter particles might possibly be made up of the lightest sterile right handed neutrino. I was wondering, why exactly does the dark matter particle have to decouple from the plasma when it is formed?

Hello, So I am aware that neutrino masses, Baryogengesis/Baryon Asymmetry, and Dark matter cannot be explained by the standard model. However each can be explained by right handed neutrinos. I know that right handed neutrinos show up in many extensions to the standard model, e.g. vMSM (where...

arXiv:1703.05772 [pdf, other] Newly-Discovered Anomalies in Galactic Cosmic Rays: Time for Exotic Scenarios? Mikhail Malkov Comments: Cosmic Rays beyond the Standard Model, San Vito, 2016, this http URL, conference paper Subjects: High Energy Astrophysical Phenomena (astro-ph.HE) Recent...

I'm trying to figure out how to best filter some liquids. A 5 gal bucket is filled with some filter medium (say sand on top 1/2 and fine charcoal on bottom 1/2). The liquid is slowly added at the top and gravity is used and vacuum may be used at some point with a complete seal along the bottom...

This suggests to me that the early universe did not contain as much dark matter. Is this correct? If so it might give a clue what D.M actually is? http://www.space.com/36083-dark-matter-minor-ingredient-of-early-galaxies.html

Hello everyone, Today I'm asking you for help to put together these two equations of state for high densities BPS-BBP with a eos of a pure neutron gas or a non interacting n + p + e gas. I have already the data of BPS-BBP equation of state, with includes neutron drip and let a open space to...

the moment there was matter there was time and thus even as time was shaping up to be the dimension we now know there must have been another dimension let's call it :"time2" in which our time was forming، can you say that? This is because time is matter as it forms the fabric of space and time.