Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Pseudoscience-is-malarkey on 27/09/2022 15:59:44
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Even if we invent a spaceship that travels at the speed of light it would take approximately 48,000 years to get to the point where we see our galaxy as a whole. However, that does not make seeing it impossible. Perhaps an extragalactic civilization in a neighboring galaxy took a photo and sent it to our galaxy for any intelligent civilization to view?
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The Magellanic Clouds are 163,000 and 206,000 ly away. While the smaller of the two would have the better view, it is also the furthest of the two. Of course, it would still take 206,000 yrs for the image to travel from them to us, not to mention the 206,000 yrs it would take for our request for said photo to reach them.
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Pseudoscience....., you are not taking relativity into account. Although not possible let us suppose for the sake of argument that your ship could travel at C. In that case it would take zero time to reach your destination while a static observer would judge your time of travel to be 48000 years.
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take a photo and send it to us.
How long would it spend "in the post"?
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Perhaps an extragalactic civilization in a neighboring galaxy can see it, take a photo and send it to us.
But by the time it reached us it would be at least 96,000 years out of date! Not much market for last year's road atlas, never mind a picture of the galaxy as inhabited by Neanderthal man. Could sell it to pubs, perhaps - they like to have historic Ordnance Survey maps on the walls.
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Maybe one day we could invent some form of neutrino telescope, which can pierce the dust in the galaxy, and plot all the stars in their 3D position?
Then we could recreate the galaxy as a 3D model?
In the meantime, we could just look at some other spiral galaxies in space, to get an idea of what our galaxy might look like...
- We know the general form of our galaxy from studying the 21cm Hydrogen line emitted by dust clouds; when Doppler-shifted, it pierces most clouds of dust - but it can't provide readings on the opposite side of the galaxy, because the Doppler Shift is zero (like the central bulge).
- Further work is refining this (but the central bulge is still an obstacle)
https://www.space.com/milky-way-3d-map-warped-shape.html
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Maybe one day we could invent some form of neutrino telescope, which can pierce the dust in the galaxy, and plot all the stars in their 3D position?
Then we could recreate the galaxy as a 3D model?
Right now I'm working on 3-D x-ray systems to do this with people. Problem is that you need at least 20 projections to usefully locate and identify anything, from at least twice as far away as the thickness of the object you are scanning. You can use a rotating x-ray source (CT scanner) if it can move quickly compared with the patient, or multiple x-ray tubes (true 3D stereoscopy) for a flash image. So you will need your neutrino telescope to orbit the galaxy at really ridiculous speed, or umpteen telescopes in galactosynchronous orbit.
If you want to use neutrinos emitted by the galaxy itself, perhaps a vast radionuclide imager would do the trick. But really vast or fast!
I think ground-based interferometry gives us a pretty good picture of galactic RF sources seen from here, from which we should be able to construct a theoretical view from elsewhere.
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Counting the stars in the Milky Way has been compared to counting all the sand grains on a beach.
One similarity is that it's pretty pointless to try to get an accurate answer.
Similarly, who needs a map of the sand?