Q: Is it true that all matter is simply condensed energy?

The complete question was: Is it true that all matter is simply condensed energy? Does that mean that the Big Bang was pure energy and coalesced into matter?


Physicist: Pretty much.  If you can get enough energy into one place (generally light or kinetic energy), then you’ll get a (mostly random) variety of particles popping out. The conversion between mass and energy is so ubiquitous in physics, that most physicists only know the mass of particles in the context of their equivalent energy.  If you ask a physicist “what is the mass of an electron?” they’ll say “0.5 MeV” (which is a unit of energy).  Frankly, it’s more important to know than the actual mass.  I mean, how hard is it to pick up an electron?  If you answered “I don’t care” or “zero”, you’re right.

The only thing that keeps particles from turning back into energy (again, usually light and kinetic) are “conserved quantities”.  If you’ve taken an intro physics course you should be familiar with conservation of energy and momentum.  In particle physics you also need things like: charge, Lepton flavor (which covers things like electrons and neutrinos), and Baryon number (which covers things like protons and neutrons).

The classic example is neutron decay:

Neutron decay: Tricky business.

A neutron is heavier than a proton, so you’d think it would decay into a proton and some extra energy (conserving energy and baryon number).  But that would violate conservation of charge (protons have 1, neutrons have zero).  So maybe it could decay into a proton and electron?  Now you’ve balanced charge, but violated lepton flavor (electrons have “electron flavor 1″).  To balance everything you need to add an anti-electron neutrino (electron flavor -1) to the mix.

The very early universe was a “particle soup”.  The mean energy of the photons flying about was more than enough to generate new particles.  These would pop into existence in balanced quantities and then cancel out again.  The big difference between now and then (why we don’t see particles being spawned off all the time) is that the average energy of photons today is closer to 660 meV (about 1 billionth of the energy needed to create electrons, the smallest particle).

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12 Responses to Q: Is it true that all matter is simply condensed energy?

  1. Luke says:

    Informative and funny.

  2. Pingback: Q: What are Feynman diagrams, how are they used (theoretically&practically), and are there alternative/competing diagrams to Feynman’s? « Ask a Mathematician / Ask a Physicist

  3. T. Reid says:

    In your response, your last paragraph raised a question for me, a non-physicist. It follows: “The very early universe was a “particle soup”. The mean energy of the photons flying about was more than enough to generate new particles. These would pop into existence in balanced quantities and then cancel out again. The big difference between now and then (why we don’t see particles being spawned off all the time) is that the average energy of photons today is closer to 660 meV (about 1 billionth of the energy needed to create electrons, the smallest particle).” My question regards the energy loss mentioned in the final sentence. Since energy must be conserved, is that lost energy the “glue” which is holding together the matter which exists after the “big bang”? If not, what did that energy convert to? What is it’s present nature? If matter is energy, energy composes matter, and there is nothing else in the equation, what else can it be?

  4. an engineer says:

    My question regards the energy loss mentioned in the final sentence. Since energy must be conserved, is that lost energy the “glue” which is holding together the matter which exists after the “big bang”? If not, what did that energy convert to? What is it’s present nature? If matter is energy, energy composes matter, and there is nothing else in the equation, what else can it be?

    The continous expansion of the universe has the effect that the same amount of energy occupies a still larger volume, thus lowering the average energy density.

  5. VINIT CHANDRAKANT GAVANKAR says:

    If we say that all is made up of energy then why there are different forms with same energy . e.g Humans , Animals , Plans are all made up of energy then due to which factor they have different forms.

  6. An astronomer says:

    I have a question about “The very early universe was a “particle soup”. The mean energy of the photons flying about was more than enough to generate new particles. These would pop into existence in balanced quantities and then cancel out again. The big difference between now and then (why we don’t see particles being spawned off all the time) is that the average energy of photons today is closer to 660 meV (about 1 billionth of the energy needed to create electrons, the smallest particle).”

    What kind of particles can be produced? Can we see it by the naked eye?

  7. The Physicist The Physicist says:

    Electrons would be the first to be created. They wouldn’t be visible on their own, but they would scatter light. That would make the area “foggy”, in addition to being flooded with high-energy radiation.

  8. VINIT GAVANKAR says:

    If we say that all is made up of energy then why there are different forms with same energy . e.g Humans , Animals ,….. are all made up of energy then due to which factor they have different forms.

  9. Kevin O says:

    Wouldn’t the one and only fundamental particle be some amount of energy, then?

  10. Kevin O says:

    T. Reid: Also a non-physicist here. My opinion is that the amount and character of matter that arose at the Big Bang are governed by equilibrium, similarly to dynamical systems and chemical reactions. This may or may not represent the views of particle physicists. It’s often difficult to tell exactly what they’re saying.
    That’s an equilibrium between “energy” and “matter.”

  11. ayush jain says:

    it is a good question that how can a same energy can produce different types of masses,,,but looking at the atomic level we can find that the constituent unit of every matter is similar …a profound difference is produced between them is just because of the different atomic arrangements ,,,may be these differences rises with the existance of different energy density at a point……more amazingly the fact is our universe constitute of mass and energy and rest of the portion is empty and interconversion goes on between mass and energy according to the famous equation E=mc^2 ,,…

  12. Xerenarcy says:

    “If we say that all is made up of energy then why there are different forms with same energy . e.g Humans , Animals ,….. are all made up of energy then due to which factor they have different forms.”

    if you look hard enough the only things that cannot be distinguished is the energy and fundamental particles themselves. their arrangement, at such tiny scales, forms progressively larger and larger structures on the allowable laws of their interactions (conservation laws, quantized energy levels, fine structure constant, etc).

    animals will have some things in common (made up of cells) and other things that are not in common (some have hair, some are larger than others). but if you examine what you assume to be in common (made up of cells) you will find further ways to distinguish them – the cells of different animals vary. you can repeat this process down to the plank volumes making up everything if you wanted to but the only way to keep track at smaller and smaller scales is how you arrived there, or working backwards, every structural choice of the smallest, gives new possibilities for the larger scale.

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