“Gravitational and electromagnetic interactions are long-range interactions, meaning they act on objects no matter how far they are separated from each other.” -Francois Englert

Want a recipe for seeing as far into the distant Universe as you can? Because of how distance and brightness are inversely related, you need to make the most of every photon, build as large a telescope as possible and observe for long periods of time in order to collect the most light.

Image credit: NASA/ESA, of an illustration of how gravitational lensing works.

Image credit: XMM-Newton, ESA, NASA.

But there’s an extra bit of magnification that Einstein’s General Relativity gives to us for free: gravitational lensing, where any large mass magnifies the light from the objects directly behind it. Thanks to this technique, we’ve discovered the most distant galaxies ever.

Image credit: NASA, ESA, R. Bouwens and G. Illingsworth (UC Santa Cruz).

Image credit: XMM-Newton, ESA, NASA.

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Comments

  1. #1 wrathOfShereKhan
    November 10, 2015

    Ethan, I was hoping this post might say something about the plausibility of using our sun as a gravitational lens, and sending a telescope far enough away to make it work (iirc the distance required is on the order of 1/100th of a light year). Of course you only get to point it at one target, aligned with your trajectory… Is it a crackpot idea, or will we probably do this one day?

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