Observable Universe contains 10x more galaxies than previously thought (2016)

Re:Observable Universe contains 10x more galaxies than previ... by woodandsteel on Thursday January 04, 2018 @05:14PM (#16074588)

I wonder how long much longer it will take for the astronomers to get the technology that would allow them to hunt for life in other stellar systems so that we can check all this out.

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Re:Observable Universe contains 10x more galaxies than previ... by Balgair on Thursday January 04, 2018 @06:24PM (#16075066)

Depends on the size of the dish, really. You need to resolve the 'signs of life' at stellar distances.

Street-Math time!:

Lets assume that means you need to resolve a meter sized elephant on another planet. Lets choose Vega, as that is ~25ly away, really the furthest star we can go to (and return from) and still have someone alive here to have a beer with afterwards (50 year round trip). 25ly is about 2.3E19 meters away.

A 1 meter sized elephant at 2.3E19 meters is about 4.3E-20 radians.

Lets use wavelengths in the visible spectrum. Hydrogen's Balmer peak at 656nm is a nice red color to look at (though stellar issues abound here).

The resolution of a telescope is approximately : R = L/D. R is resolution, L is the wavelength, D is the diameter. Rearranging we get the diameter to be : D = L/R. Plugging in a L of 656nm (~6.6E-7m) and a R of 4.3E-20radians and you get D.

D is about 1.5E13 meters.

For reference the earth is about 1.2E7 meters, about 6 orders of magnitude smaller. 1.5E13 meters is about 14 light-hours, much larger than the Earth-Sun distance.

Soooooo, I think it's going to be a while ...

;)

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