The mystery of dark energy: This Week in Astronomy with Dave Eicher

 



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A lot of the mass-energy of the universe is darkish power — and we do not actually perceive what it’s in any respect.

The tempo of the universe’s enlargement is rushing up, not slowing down. Credit score: NASA’s Goddard Area Flight Middle Conceptual Picture Lab

What’s a lot of the universe product of? The reply isn’t stars, galaxies, and even dark matter. As an alternative, over two-thirds of the universe is power — a mysterious type of it that’s pushing the universe aside sooner with each passing second.

This astonishing reality was found in 1998 by two groups of astronomers observing distant Sort Ia supernovae. These are white dwarf stars that explode in a runaway thermonuclear response when their mass exceeds roughly 1.4 instances that of the Solar. This constant threshold implies that Sort Ia supernovae are all about the identical brightness. So, when one goes off in a faraway galaxy, we will decide its distance based mostly on how shiny it seems to us. The fainter it seems, the farther it should be. These observations revealed that distant galaxies have been receding a lot sooner than predicted, and that the universe’s enlargement was not slowing down or staying regular, however accelerating over time.

This supply of this acceleration is what we now name darkish power — and what precisely it’s stays a thriller. The only clarification could be represented mathematically by what theorists name a cosmological fixed, written in equations by the Greek latter lambda (Λ). One interpretation of the cosmological fixed is that it’s a drive that’s a part of space itself — and in order the universe expands, the quantity of darkish power grows. However merely with the ability to seize this in an equation doesn’t inform us a lot about its nature.

The leaders of the supernovae survey groups who found the accelerating universe shared the Nobel Prize in physics in 2011. Should you can determine what darkish power is, you’re positive to snag one your self.

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