1
$\begingroup$

Is it possible that some of the stars and galaxies we observe here on Earth are actually replicates of other stars and galaxies we are observing from different angles because of curved spacetime?

Let's say there is a star a few billion light years away. It emits photons in all directions. Some photons are travelling in a semi-direct path towards Earth. Some photons are travelling in a 90 degree angle away from Earth, so we'd never see them. However, over time the star's photons that started off moving 90 degrees away from Earth pass by giant black holes -- maybe even a series of black holes -- not close enough to get caught, but close enough it bends the light altering it's trajectory enough to put it on course to be observable on Earth.

Based on that example -- if possible -- then there would be a few differences in the way it looked when we observed it even though it is from the same source:

  1. We'd observe the star from two points in time.
  2. We'd observe the star from two different distances.

If this is possible, how would we know it -- or, could we know it?

Conceptually, it would be as if the universe had a bunch of mirrors (gravity) scattered throughout taking light coming in from one angle and reflecting (curving) it so it is observable at an otherwise impossible angle much like a dressing room where we can see ourselves from multiple angles simultaneously.

It would probably only be possible for very distant, very bright objects -- if at all.

Thanks for your thought nuggets...

$\endgroup$
  • $\begingroup$ As a follow-up, what extreme of this effect might be theoretically possible? Might we see a galaxy or star, from opposite directions in our horizon so distorted by gravity we observe them at a billion years time difference (i.e. one angle takes 1 billion years, another curved angle takes 2 billion years to reach Earth). Furthermore, is it possible we see a lot of these extreme cases without knowing it because it is so observably different it is essentially undetectable? If so, is it then possible there is less mass in the universe than we currently theorize? $\endgroup$ – Levi Mootz Aug 9 at 10:19
3
$\begingroup$

It's totally possible and, moreover, happens time to time due to the gravitational lensing. As a good and quite famous example, you can search for the Einstein Cross, which is a gravitationally lensed quasar, appearing to be four times the same object. I believe that, when such lensing happens, the spectral properties of the light from the lensed object posses specific properties, which allows for attribution of several observed "instances" to one light source.

$\endgroup$
2
$\begingroup$

This has been observed several times so it is very much an existing phenomenon. It is called gravitational lensing, and there is one famous hubble image where the same galaxy is present a couple of times with a circular structure.enter image description here

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.