The cartoon reads:"The universe is an illusion ... the starlight we see tonight actually started its journey millions of years ago ... for all we know, the universe could have ended and we´re still waiting for confirmation"
Ohio State University has a course on Star, Galaxies and the Universe where you will find key notions of the study of the universe. It is not long and it summarizes concepts we have read about so far.
Look at what it says about Lookback time:
We observe the Universe using light, but light moves at a finite speed: It takes time for light to reach you from a distant source. Example: we see the Sun as it was ~8.5 minutes ago due to the time it takes light to travel 1AU. At cosmic distances, the effect is even more pronounced:
The deeper we look into the Universe, the further we are actually looking back in cosmic time to when the Universe was younger and smaller.
This fact allows us to reconstruct the past expansion history of the Universe, provided, as always, that we can measure distances accurately.
This is a startling fact: cosmic lookback time means that we can actually observe the Big Bang unfolding from the past to the present!
Classmates recommended this video about Black Holes, this reading on the end of cosmology, and the best images taken from the Hubble space satellite (did you know there is a sombrero galaxy?). Enjoy!
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