What is Matter: Definition and 1000 Discussions

In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particles, and in everyday as well as scientific usage, "matter" generally includes atoms and anything made up of them, and any particles (or combination of particles) that act as if they have both rest mass and volume. However it does not include massless particles such as photons, or other energy phenomena or waves such as light. Matter exists in various states (also known as phases). These include classical everyday phases such as solid, liquid, and gas – for example water exists as ice, liquid water, and gaseous steam – but other states are possible, including plasma, Bose–Einstein condensates, fermionic condensates, and quark–gluon plasma.Usually atoms can be imagined as a nucleus of protons and neutrons, and a surrounding "cloud" of orbiting electrons which "take up space". However this is only somewhat correct, because subatomic particles and their properties are governed by their quantum nature, which means they do not act as everyday objects appear to act – they can act like waves as well as particles and they do not have well-defined sizes or positions. In the Standard Model of particle physics, matter is not a fundamental concept because the elementary constituents of atoms are quantum entities which do not have an inherent "size" or "volume" in any everyday sense of the word. Due to the exclusion principle and other fundamental interactions, some "point particles" known as fermions (quarks, leptons), and many composites and atoms, are effectively forced to keep a distance from other particles under everyday conditions; this creates the property of matter which appears to us as matter taking up space.
For much of the history of the natural sciences people have contemplated the exact nature of matter. The idea that matter was built of discrete building blocks, the so-called particulate theory of matter, independently appeared in ancient Greece and ancient India among Buddhists, Hindus and Jains in 1st-millennium BC. Ancient philosophers who proposed the particulate theory of matter include Kanada (c. 6th–century BC or after), Leucippus (~490 BC) and Democritus (~470–380 BC).

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  1. elou

    A There is no wave

    This is meant as a challenge to look more closely than we usually do to the concepts of "wave" and "particle". You often hear that matters moves as a wave but hits at a particle, making it sound like a super Mohamed Ali's "move like a butterfly and sting like a bee". To give a simple example I...
  2. M

    B Dark matter and extreme gravitational regimes

    If dark matter really lives up to it's name and truly is some form of matter, then wouldn't it feed black holes given extreme gravitational regime in a black hole?
  3. SilverMain

    I Questions about the Location of the Big Bang and the Age of the Universe

    Assumed facts: Galaxies are traveling at velocities that cause very little compression of space. The big bang occurred at one point in space and all matter is moving away from this location. The universe is continuing to expand The farthest galaxies are about 92 billion light years apart or 46...
  4. L

    B Does the Universe prefer certain kinds of matter based on the laws in place?

    My understanding is when a star creates new matter it has an affinity towards iron? Does the universe on a whole favor certain elements based on the laws in place? Certain complexity level and certain physical characteristics are ideal and the farthest from those things the stronger the force to...
  5. J

    B How can a single Big Bang be true?

    How can a single Big Bang be true if matter is disappearing into multiple holes within multiple galaxies throughout the cosmos and no matter how far back into the cosmos scientist look the galaxies are as mature as the galaxy we reside within?What matter will be left exactly to actually...
  6. A

    Can energy truly be converted into matter in our world?

    Theoretically possible, only if the process is reversible. But is it really. My knowledge base is insufficient to answer that. I need help.
  7. Slimy0233

    I Questions Regarding Primitive Unit Cell

    Questions regarding Primitive Unit Cell (and what I think the answer are, correct me if I am wrong) 1. Can there be more than one Primitive Unit cells for the same crystal? yes, Wigner Seitz cell always will exist. There can be other primitive Unit cells along with Wigner Seitz too. But...
  8. .Scott

    B Images with CMB used to Illuminate Dark Matter

    A collaborative effort is yielding a Dark Matter picture of the universe from microwave (CMB) data collected by the Atacama Cosmology Telescope. Major sections of the sky have already been imaged. Those are shown in the image below as the red/blue speckled regions (from a University of Toronto...
  9. M

    A Photon dilemma for MOND-like dark matter

    "Superfluid dark matter in tension with weak gravitational lensing data" (Mistele, McGaugh, Hossenfelder) Regarding this paper, Sabine Hossenfelder tweets One comment summarizes this as
  10. S

    B Magnetic Field & Particle Spin: Does It Matter?

    Does the magnetic field caused by moving particles depend on the particle spin value? Eg a stream of say protons spin 1/2 is creating a magnetic field. If the particles are (say) lithium nuclei spin 3/2 instead, does that create the same strength field ? (same conditions of course)
  11. D

    B Subatomic particles and dark matter

    I am by no means an expert in physics, but I have a question. We have recently found the particle that cause attraction (Bos-Higgs) would it not be reasonable to think the there is a particle that cause repulsion? That would lead to cluster of attraction surrounded by fields of expansion. Would...
  12. Mustafa Bayram

    I Diffraction of Matter: Examining Bohr's Theory

    Does matter (like electrons) diffract at the single slit and create an interference pattern on the screen? If it's not why? Isn't that violation of Bohr's Theory?
  13. hudsonj

    Intro Physics Pop-sci books about condensed matter physics or superconductivity?

    I was wondering if anyone knows of any technical pop-sci books about condensed matter physics and/or superconductivity that are at the technical level of something like the "A Very Short Introduction" series or the Feynman lectures. That is, something that goes sufficiently into depth into the...
  14. bakerjay

    A Data on galaxy rotation curves vs visible matter

    I'm after some raw data for testing theories of dark matter in galaxies. Basically what I want is table showing visible mass vs total mass within different radii (or, observed rotational velocity vs expected rotational velocity without dark matter). Plus error percentages. And ideally, for...
  15. GreenLemon

    I Exploring the Possibility of Dark Matter as Stray Exoplanets or Collapsed Stars

    I was thinking about how the dark matter theory was proposed due to inconsistencies with observed mass vs the calculated required mass for a galaxy to exist. Just wondering how we know its not just stray exoplanets or possibly even smaller collapsed stars, really any kind of mass that wouldn't...
  16. Omega0

    About the pointwise or distributed form of matter

    Please help me in understanding the history of physics regarding the atomic or non-atomic, say continous, structure of physics. In my years at school I grew up with physics of ultimate simplifications. Everything was a point "particle", like the moon revolving around the earth. Like the apple...
  17. Kostik

    A Dirac's Conservation of Matter: A Closer Look

    In Dirac's "General Theory of Relativity", at the end of Ch. 25 (p. 47), right after deriving the full Einstein equation ##R^{\mu\nu} - \frac{1}{2}g^{\mu\nu}R = -8\pi\rho v^\mu v^\nu = -8\pi T^{\mu\nu}##, he makes a reference to the conservation of mass (Eq. 25.3): $$0 = (\rho v^\mu)_{:\mu} =...
  18. Ranku

    I What is the difference between collisionless and self-interacting dark matter?

    When dark matter is called collisionless, does it only mean that they do not collide and scatter, or does it also mean that there is no other significant non-contact interaction?
  19. Frabjous

    I Local dark matter distribution

    We do not seem to have any unexplained orbital/gravitational anomalies within the solar system. What does that imply for the local dark matter distribution?
  20. Ranku

    I CMBR Evidence for Non-Baryonic Dark Matter

    It is said that CMBR indicates that dark matter is non-baryonic. How so?
  21. F

    A Does WHIM solve the dark matter problem?

    Direct Observation of Whim (The warm–hot intergalactic medium) has known a lot progress recently. Does whim could be enough to amount to the quantity of dark matters in the universe, therefore solving the dark matter problem? If not, why?
  22. Mr Fallspring

    I Double-Slit Experiment: Does rate of photon emission matter?

    Hi there! High school physics teacher hoping to pick the brains of people who know more than I do here. I'm curious whether the rate of photon emission has any noticeable effect on the diffraction pattern generated by the double-slit experiment. To be clear: I understand a diffraction pattern...
  23. mpross

    B Dark Energy, Dark Matter and the Speed of Light

    Quote from NASA: My understanding of dark energy is based on NASA's report: https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy; were NASA state as follows: "It turns out that roughly 68% of the universe is dark energy. Dark matter makes up about 27%. The rest - everything on...
  24. A

    Solid State Best resources to learn topological condensed matter in 2022?

    Hello, I was not sure whether this should belong to this section or the condensed matter section. I am wondering if after about 15 years in research in topological condensed matter, there exist well-recognized references for beginners in the topic. Books or courses but also review articles...
  25. K

    I Primordial neutron star -- a new candidate for dark matter

    could this explains the 3rd peak of the CMB and dark matter cold Primordial neutron star High Energy Physics - Phenomenology [Submitted on 7 Sep 2022 (v1), last revised 12 Sep 2022 (this version, v2)] Primordial neutron star; a new candidate of dark matter M. Yoshimura Z-boson exchange...
  26. H

    Energy conservation: electromagnetic wave in matter

    Hi, I completely failed this homework. I mean I think I know what happen, but I don't know how to show it mathematically. The energy lost by the wave is used to oscillate the electrons inside the conductor. Thus, the electrons acts like some damped driven oscillators. I guess I have to find...
  27. DaveC426913

    B Gravitomagnetic explanation of Dark Matter

    I was reading a thread on my phone that was reviewing a paper about DM being explainable by gravitomagnetic effects. Now I can't find it in any search. It was on its fourth page - so at least 80 posts over at least two years. Anyway, what I wanted to ask was for a description that a layperson...
  28. G

    I Data Showing Dark Matter Is Not Cold Neutrinos?

    How do we know that cold neutrinos do not make up 100% or a large percentage of the dark matter content in the universe? In my mind, the only way to prove that dark matter is not simply cold neutrinos would be to measure the density of cold neutrinos in the universe and then calculate the...
  29. M

    B Matter and Friction: Adhesion, Deformation & Hydraulic Press

    Friction happens because of adhesion between high points of the pertubrances of the two surfaces. The pertubrances deform. More the force between surfaces more deformation. Is the deformation elastic or inelastic? Will the surface of one body become smoother if pressed with hydraulic press?
  30. Saalz

    Engineering Applying Physics to Vehicle Dynamics: Do Wheel Number Matter?

    I was modeling the dynamics of a vehicle for a project, and started doubting about the way of applying physics in this particular case. The thing is, I know the torque in the wheels from the torque the electric motor I designed do provide, multiplied by the gearbox ratio. I also know the...
  31. T

    B What is the recession speed today of the matter which created the CMBR?

    Hello, I am talking to a Quantum Mechanics Physicist friend who is having a hard time accepting some of the Cosmology theories and numbers and I want to be sure that my numbers were correct. 1. Firstly, what is the recession speed, today, of the matter which created the CMBR? I told him that...
  32. Ranku

    I Identification of matter and dark matter proportions

    Is it possible to identify a volume of space, observationally/statistically, that represents the 85:15 % ratio of dark matter and matter?
  33. S

    I Matter Gaining Energy from Expanding Spacetime?

    Sean Carroll has an article (https://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/) where he explains that matter can gain energy from spacetime expansion. At the end of the article, he says: In general relativity spacetime can give energy to matter, or absorb it from...
  34. Ranku

    I Rotation curve and dark matter

    Do all galaxies with dark matter halo have flat rotation curve?
  35. pinball1970

    I Distant Galaxy study, dark matter and the CMBR

    The article is pop but there is a paper Pop article https://www.vice.com/en/article/g5vvjw/the-universes-oldest-light-reveals-unprecedented-dark-matter-patterns Paper. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.061301 The language is a little bit click bate, I just wanted...
  36. Z

    Can Conservation of Energy Be Applied to the Expanding Universe?

    Can matter be destroyed?
  37. cemtu

    Solid State Good Condensed Matter Physics Books and Semiconductor Physics Books

    Can you please recommend me some condensed matter physics study books and semi-conductor physics study books? Much Appreciated!
  38. A

    I Bullet cluster and dark matter

    Is the bullet cluster evidence for or against dark matter? I understand the explanation that it is evidence in favor of the existence of dark matter, and it convinces me. However, some argue that it is evidence against its existence? Why?
  39. ohwilleke

    A LQG Legend Writes Paper Claiming GR Explains Dark Matter Phenomena

    A new group of investigators are attempting something similar to Deur's work, which seeks to explain dark matter phenomena with general relativity corrections to Newtonian gravity is systems like galaxies. Deur's most similar publication to this one along these lines was: One thing that makes...
  40. mfb

    I Seminar: First LUX-ZEPLIN dark matter search results

    Today 16:00 UTC, in ~7.5 hours. Announcement, Link to Zoom meeting (why is this just an image on the website, not a link?) LUX-ZEPLIN (LZ) uses several tonnes of xenon to search for signals of dark matter interacting with it. It started taking data last year and it should easily set better...
  41. P

    Undergraduate modern physics and condensed matter physics courses

    Do they really teach and help anything? I am taking them for my nanoengineering undergraduate program. The textbooks are solid state physics by j r hook and concepts of modern physics by mcgraw hill and r b singh introduction to modern physics and introduction to quantum mechanics by david j...
  42. P

    Other Does prestige of school matter for post-graduate research positions?

    Apparently I always find myself back here when bad things happen lol..like damn it’s been six years. Recent college graduate. I want to take a year or two working and honing my skills before graduate school. One, because I’m tired and need the break but also, two, for reasons beyond my control...
  43. lindberg

    I Relativistic Velocity Addition: Calculating Electron Speed

    If we imagine launching an electron wave in a reference frame S with speed v, should someone viewing the electron from frame S1, which is in inertial motion referring to S, use the relativistic velocity addition to calculate the speed of the electron?
  44. P

    I Ultra-high energy photon interactions with matter

    While this was inspired by another thread, I think the question is different enough that it can be asked separately. It's also more suited to this forum than the forum where the question that inspired this one was asked. Wiki gives four possible interactions for interactions of gamma rays with...
  45. B

    But in the end, it doesn't even matter

    in the grand scheme of things, our life is an imperceptible blip on the universe's timeline. we are insignificant, and we don't really matter. no matter how successful we are in life, or how our lives end, all our accomplishments will be erased during the heat death of the universe, along with...
  46. Philip Koeck

    I Phase velocity and frequency of a matter wave

    The relationships for matter waves are (see e.g. https://en.wikipedia.org/wiki/Matter_wave): λ = h / p and E = h f, where E = m c2 From this the phase velocity can be derived and we get vph = c2 / v. v is the group velocity, which is also the velocity of the particle. If I consider these...
  47. alexandrinushka

    B Sagnac effect for matter beams

    Hello, I have recently come across this article by Rizzi and Ruggiero, called "The Relativistic Sagnac Effect: Two Derivations": https://arxiv.org/pdf/gr-qc/0305084.pdf In section 3, the authors derive the Sagnac proper time difference for all beams (light beams and matter beams, including...
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