Matter Definition and 1000 Threads

  1. J

    Compacting Matter in a Black Hole Singularity: Is It Pure Entropy?

    Information that is ordered can be compacted down to a single repeating unit i,e; 110055110055110055110055 down to just 110055 and this meant that it must have been highly ordered to be compacted down this far. So could it be that matter is also highly ordered somehow and it can be compacted...
  2. jim mcnamara

    Could Dark Matter Be the Source of Anomalous X-ray Emissions?

    This is a video by the two of the researchers who found anomalous xray emissions. These emissions may be related to dark mater, needs further verification. Edit 12/14/14 : preprint http://arxiv.org/abs/1402.4119
  3. M

    Should we describe protons and electrons in dar Matter in a different way?

    I was wondering if protons and electrons have different description in the terms of quarks if they're in Dark Matter??
  4. J

    Disappearance of dark matter since the Big Bang

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

    Dark Matter and extra dimensions

    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...
  6. S

    Why does name of the university matter so much in job search

    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...
  7. L

    Light travel time since dark energy - matter equivalence

    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 =...
  8. V

    Speed of Dark Matter: Exploring Universe Creation

    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...
  9. 0

    Using gravity to suck matter from a star (Lexx)?

    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...
  10. W

    Basic question about spacetime and matter

    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...
  11. Q

    Is there any evidence for MACHOs or WIMPs being Dark Matter?

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

    Calculating Temperature and Pressure in a Sealed Container of Helium Gas

    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...
  13. ubergewehr273

    Is Fire or Electricity Considered a State of Matter?

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

    Matter Alignment: Magnatism Effects on Salt Water Flow

    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
  15. B

    Help please -- Is my list okay so far for Condensed Matter? (grad app.)

    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!)...
  16. TrueGormagon

    Is Exotic Matter the Key to Advancing Human Technology?

    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...
  17. N

    The State of Energy to Matter Experimentation

    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...
  18. Eric Hentschel

    Exploring Dimensions of Energy & Matter: A Curious Inquiry

    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.
  19. I

    Excluding a simple dark matter candidate

    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...
  20. Ritzycat

    Can all matter be potentially annhilated?

    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...
  21. 1

    Applying condensed matter physics/ soft matter physics to medicine

    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?
  22. 1

    Research areas in condensed matter physics

    What are some exciting research areas in condensed matter physics at the moment?
  23. jbrussell93

    Does course load matter in final semester?

    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...
  24. V

    Matter at the core of neutron star

    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.
  25. K

    Conservation of matter, mass, rest mass and energy

    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...
  26. M

    Can the Larmor formula explain the stability of electron rotation?

    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...
  27. K

    Why can light go through some matter but not other matter?

    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.
  28. L

    The Space Between Atoms -- Teaching Middle School

    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...
  29. A

    Why two terms "Dark Energy" and "Dark Matter"

    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...
  30. E

    Question on electron straggling in matter

    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...
  31. K

    Why can't matter go through other matter?

    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...
  32. K

    Dark Matter Worlds - Explore the Possibilities

    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...
  33. Shing Ernst

    Recent important observations on dark matter for an undergrad research

    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...
  34. I

    C/C++ Understanding Arrays & Vectors: What They Do & Why They Matter

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

    Dark matter possibly explained by axions?

    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
  36. E

    Diffeomorphism and removal of all matter from the spacetime

    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...
  37. J

    What fraction of the Sun’s total mass is lost during fusion?

    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...
  38. K

    Contradiction in Couple Force: Can Its Point of Application Matter?

    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...
  39. M

    How do I be like these guys? (does major matter that much?)

    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...
  40. C

    Energy and matter equivalence

    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...
  41. J

    Is there an acid that could dissolve plant matter quickly?

    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...
  42. B

    How Did We Develop Early Models of the Atom?

    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...
  43. M

    Quantum Measurement Problem: Nature of Matter or Nature of Probability?

    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...
  44. P

    Useful skills/math courses in condensed matter physics

    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...
  45. C

    Dark Matter: Why doesnt dark matter coalesce 'into' Ordinary Matter - Repost

    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...
  46. C

    Event Horizon Properties for Incoming Matter Explained

    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...
  47. R

    Acceleration does not matter when driving

    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...
  48. J

    Photonic density of state in matter

    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...
  49. C

    Is Dark Matter Only Interacting Through Gravity or Are There Other Theories?

    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...
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