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"Hubble Science"

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"Dark Energy: A Mysterious Force"

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Because the Hubble Space Telescope is operating so 
well and is so scientifically effective right now,  

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scientists are using Hubble to investigate 
some of the deepest mysteries of the universe.  

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One mystery is dark energy, 
that's the name just kind of  

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plastered on this phenomenon that 
Hubble and other telescopes together,  

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we found that the universe expansion has been 
accelerating for the last few billion years.  

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Well, what is causing that? We don't know, it's 
something about a repulsive force that we may not  

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fully understand, or new physics that we don't 
fully understand. But Hubble was used along,  

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in complement, with some telescopes on the ground 
to determine that the expansion of the universe  

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is in fact accelerating by something we're now 
calling dark energy, and without Hubble, we  

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would have not been able to make this detection, 
which is now a Nobel Prize winning discovery.

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This explains why the universe appears to be 
accelerating now, when it used to be slowing  

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down because of gravity. So now the question is, 
well, is this a simple story or is it complicated?  

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Is there more than one kind of dark energy? 
Has the dark energy itself changed over time?

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So Hubble is now being used to refine, even 
further, that expansion rate of the universe  

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in our current epoch, and trying to 
compare that to what might be predicted  

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from looking at other measurements of 
the universe with other telescopes.  

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Right now, we're finding a discrepancy 
between what we might have expected and  

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what we're actually measuring. So that's 
one realm where Hubble is really at the  

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cutting edge of helping us understand, or at 
least open up new mysteries of the universe.

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