What Is Matter?

Learn in a couple minutes:

I ran this by a padawan physicist (i.e., a physics graduate student) and here was his verdict on the accuracy:

It’s cute and amusing, but accurate. There are two caveats I’d add though. Pauli exclusion principle prohibits two electrons from being in the same state, or two muons from being in the same state, but an electron and muon can be in the same state. So electrons (and matter made up of electrons) ‘take up’ space in the respect that they prohibit other electrons from entering it, but matter made of a different species of particle would not be prohibited from entering the space ‘taken up’ by electronic matter. It’s not too important a point though, since matter in the real world is made up of electrons and atomic nuclei.

The other is that the Pauli exclusion principle applies to different species of particles called fermions, with intrinsic angular momentum with half-integers of the reduced Planck constant, but it does not apply to bosons, with integer spin. (Photons and the Higgs are examples of bosons.) So photons don’t take up space, and neither does light, in any regard.

So I don’t know whether light/radiation qualifies as matter, and I think in the past it was considered something different than matter. I guess it depends on who you ask. But this is probably because ‘matter’ isn’t really a technical term with a specific definition in physics.

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About Daniel Fincke

Dr. Daniel Fincke  has his PhD in philosophy from Fordham University and spent 11 years teaching in college classrooms. He wrote his dissertation on Ethics and the philosophy of Friedrich Nietzsche. On Camels With Hammers, the careful philosophy blog he writes for a popular audience, Dan argues for atheism and develops a humanistic ethical theory he calls “Empowerment Ethics”. Dan also teaches affordable, non-matriculated, video-conferencing philosophy classes on ethics, Nietzsche, historical philosophy, and philosophy for atheists that anyone around the world can sign up for. (You can learn more about Dan’s online classes here.) Dan is an APPA  (American Philosophical Practitioners Association) certified philosophical counselor who offers philosophical advice services to help people work through the philosophical aspects of their practical problems or to work out their views on philosophical issues. (You can read examples of Dan’s advice here.) Through his blogging, his online teaching, and his philosophical advice services each, Dan specializes in helping people who have recently left a religious tradition work out their constructive answers to questions of ethics, metaphysics, the meaning of life, etc. as part of their process of radical worldview change.

  • Steve

    Look up white dwarfs, electron degeneracy pressure and the Chandrasekhar limit for a nice application of the Pauli exclusion principle in astrophysics

  • F

    Light is energy, does have a mass component, but is not matter.

    • Padawan Physicist

      Energy is a formless and abstract quantity. Light itself has a form. It also has, besides energy, momentum and angular momentum. It’s just as meaningless to say “light is energy” as it is to say “light is angular momentum.” Light also does not have mass.

  • http://www.atheistfoundation.org.au/ Peter B.

    Perhaps not quite on topic, but as reported on Wired recently(http://www.wired.com/wiredscience/2012/02/w-boson-higgs/)…

    The W boson’s new mass is 80.387 giga electron volts, or GeV, plus or minus 0.019 GeV. (Scientists often give a particle’s mass in units of energy because, according Einstein’s famous E=MC² equation, the two are interchangeable.) The most precise previous measurement had an uncertainty of about 0.060 GeV.

    Now that’s nearly half an order of magnitude reduction of the uncertainty.

  • http://www.karnatakaforum.com/ Karnataka

    Thanks for the enlightening articles.