5% of the Universe is Normal Matter, What About the Other 95%?

Posted on April 29, 2011  Comments (5)

Dark Matters from PHD Comics on Vimeo.

Great discussion and illustration of the state of our understanding of physics, matter, dark matter and the rest of the stuff our universe has from PhD comics. What is the universe made of? 5% of it is normal matter (the stardust we are made of), 20% dark matter and the other 75% – we have no idea!

Dark Cosmos is a nice book on some of these ideas. It is 5 years old so missing some of the latest discoveries.

Related: Why do we Need Dark Energy to Explain the Observable Universe?The Mystery of Empty SpaceFriday Fun, CERN Version

NASA puts the values of what the universe is made of at:
4.6% atoms – normal matter, the stardust that our planet and we are made of.
23% cold dark matter – dark matter is likely to be composed of one or more species of sub-atomic particles that interact very weakly with ordinary matter. Particle physicists have many plausible candidates for the dark matter, and new particle accelerator experiments are likely to bring new insight in the coming years.
72% dark energy – the first observational hints of dark energy in the universe date back to the 1980’s when astronomers were trying to understand how clusters of galaxies were formed. Their attempts to explain the observed distribution of galaxies were improved if dark energy was present, but the evidence was highly uncertain. In the 1990’s, observations of supernova were used to trace the expansion history of the universe (over relatively recent times) and the big surprise was that the expansion appeared to be speeding up, rather than slowing down! In 2003, the first Wilkinson Microwave Anisotropy Probe (WMAP) results came out indicating that the universe was flat and that the dark matter made up only ~23% of the density required to produce a flat universe. If 72% of the energy density in the universe is in the form of dark energy, which has a gravitationally repulsive effect, it is just the right amount to explain both the flatness of the universe and the observed accelerated expansion. Thus dark energy explains many cosmological observations at once.

5 Responses to “5% of the Universe is Normal Matter, What About the Other 95%?”

  1. Alex Aguilar
    April 30th, 2011 @ 7:19 pm

    Just when you thought you couldn’t be even more insignificant in a vast universe there’s always some new discovery in astrophysics that guarantees to make you feel even smaller! So essentially we exist and interact with 4.6% (matter) of the universe and the rest is stuff (dark matter, dark energy) is part of some unknowable mysterious void.

    The mental image I get is that we’re like tiny viruses struggling to make our way on the surface of a vast lake of whose size, depth and composition we’re only starting to comprehend.

  2. daniel
    May 7th, 2011 @ 5:12 pm

    It seems like everything I ever learned in physics has been revamped with new breakthroughs and even many of these keep getting revised every 5-6 years. It makes me realize how little we all know even now.

  3. More Dark Matter Experiment Results » Curious Cat Science and Engineering Blog
    June 9th, 2011 @ 6:45 pm

    […] matter accounts for nearly 90 percent of all matter in the universe, yet its identity remains one of the biggest mysteries of modern science. Although dark matter is invisible to telescopes, astronomers know it is there from the […]

  4. Annabelle
    June 14th, 2011 @ 11:32 pm

    I love the way Quantum Physics is heading towards the theory that the energy has a conscience and can make decisions. It fits perfectly with the Law of Attraction and draws science and religion together.

    Annabelle Drumm

  5. Explaining the Higgs Boson Particle Again » Curious Cat Science and Engineering Blog
    March 10th, 2014 @ 10:04 am

    another great explanation of science from PhD comics

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