Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: rob van valen on 20/12/2016 09:29:07
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rob van valen asked the Naked Scientists:
Love your show (http://www.thenakedscientists.com/HTML/podcasts/), especially Dave Ansell and his physics. His voice reminds me of a raver I used to party with in the clubs back in the day. Â My question is:
They say that when you look directly at the light being emitted from a star, it is like looking back in time. Â Is it possible to look in the opposite direction from a celestial body and use the light being emitted to see further back in time of the early days of stars and the universe?
Thank you and keep up the great work
Rob
Lower East Side Manhattan, NYC
What do you think?
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That is true in the sense of it being 'emitted' a long time ago. One lightyear is the time it take light to 'propagate' for one year astronomically. As the universe is about 13.7~ ly then that should be the limit, although you have a lightfog of sorts those first instants. And it doesn't matter from where you look, the distance to the 'origin' will be the same everywhere. Ponder that :)
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"Is it possible to look in the opposite direction from a celestial body and use the light being emitted to see further back in time of the early days of stars and the universe?" not sure what you mean here? If you mean looking at the light trying to see a image of the 'universe' at that time, no. If you mean looking at what information the light contain? Wavelength, red or blue shift etc?
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well yes then :) What we see is galaxies etc, and those views depend on the distance in ly. So watching something 13 billions ly away is also watching something that happened a long time ago, reaching our eyes just now. But I don't think that view represent a whole universe at that time, maybe it does though? I know I wasn't there anyway :)