World Science Scholars
4.2 Dark Energy
summary
There are still many answers to discover.

  • In 2011, Adam Riess shared the Nobel Prize in Physics with Brian P. Schmidt and Saul Perlmutter. But their work was far from over.
  • We still do not understand the quantum underpinnings of dark energy, and still do not have a quantum theory of gravity.
  • What we do have is the “recipe” for the universe. We know it’s made of about 0.05% planets, 0.5% stars, and 4% gas. Less than 5% of our entire universe is made of normal (what we refer to as baryonic) matter.
  • About 25% of the universe is dark matter, and the remaining 70% is dark energy, meaning about 95% of the entire universe is in a form that we don’t quite understand.
  • Fortunately, new instrumentation continues to help us probe these mysteries. In 2009, astronauts returned to the Hubble Space Telescope and installed two new cameras to aid in dark energy research.


New techniques for studying dark energy are constantly being invented.

  • One new technique that Adam Riess is using with the new Hubble cameras is an improvement to the method of parallax.
  • As previously mentioned, parallax loses accurate when the stars are very far away—for some such supernovae, the angle change his team is trying to measure can equate to 1% of a single-pixel on the Hubble’s detector.
  • To increase the accuracy of these measurements, the camera is “dragged” along one direction while the shutter is open. Instead of getting two points of light, the telescope now measures two parallel lines of light.
  • This makes it much easier to measure the separation—many more points of reference are involved in the measurement.


Studying dark energy is incredibly exciting for astrophysicists.

  • Most of our universe consists of dark energy and we still do not understand its fundamental properties.
  • Dark energy will dictate the fate of our universe, depending on how it changes over time.
  • Most excitingly, the research touches upon three of the central pillars of modern physics—quantum mechanics, general relativity, and string theory.
  • Studying dark energy might give us a clue of how to study physics at the interface of incompatible and mysterious regions of physics.



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