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  • b

  • baryonic matter
    All the matter that we ordinarily deal with in everyday life is baryonic matter. Baryonic matter is composed of atoms which(...) - Read More
  • Bohr atom
    Even though it’s now considered obsolete, Niels Bohr took a huge step forward in quantum physics, when in 1913, he proposed(...) - Read More
  • c

  • complex number
    This is an example of a complex number: 3 + 4i. It means take 3 and add 4 times i. The letter i is the symbol for the square(...) - Read More
  • conservation laws
    Physics includes several conservation laws. The most well-known is the Law of Conservation of Energy. This law states that(...) - Read More
  • conservation of energy
    The Law of Conservation of Energy says that in our universe the amount of energy remains constant. Energy cannot be created(...) - Read More
  • conservation of matter
    The Law of Conservation of Matter was abandoned as inaccurate by physicists early in the 1900’s. For more information, see(...) - Read More
  • conserved quantity
    A conserved quantity is something that remains constant in amount over time and cannot be created nor destroyed. Conserved(...) - Read More
  • constant

    A constant is a number or symbol that always has the same value. There are four types of constants:

    A mathematical(...) - Read More

  • constant of nature
    A constant of nature is another way of saying a "physical constant." - Read More
  • Coulomb's Law
    Coulomb’s Law is a formula that allows us to calculate the electric force generated between two electrical charges.(...) - Read More
  • d

  • dark energy
    Dark energy is the name given to an unexplained aspect of the universe. Dark energy has been postulated as an explanation(...) - Read More
  • dark matter
    "Dark matter" is a name that’s been given to a substance which many scientists believe may exist. If it exists, this(...) - Read More
  • decoherence
    (Also called “quantum decoherence.”) Decoherence occurs when a quantum particle loses its coherence. So, what is coherence?(...) - Read More
  • dimensionless number
    Pi is an example of a dimensionless number. A dimensionless number doesn’t imply any measurement units. Pi is just 3.14, not(...) - Read More
  • e

  • e
    e is the symbol for Euler's number. Similarly to pi, e is a constant which occurs repeatedly throughout nature. It has a(...) - Read More
  • Euler's number (e)
    Euler's number, similarly to pi, is a constant which occurs repeatedly throughout nature. It is symbolized as e. It has a(...) - Read More
  • experimental physics
    For experimental physics, see  theoretical physics. - Read More
  • f

  • fine-structure constant
    See alpha, , α.  - Read More
  • Free Will Theorem
    Do quantum particles have free will? Can they make choices? Some physicists have considered this question seriously. But(...) - Read More