Re: Spaceships and astronomy
Originally Posted by SultanOfSwing
(Post 12639569)
Yeah, once you start zooming out like that you start to get close to Total Perspective Vortex type situations.
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Re: Spaceships and astronomy
Originally Posted by steveq
(Post 12639570)
Which reminds me, I need a nice hot cup of tea.
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Re: Spaceships and astronomy
That is a very cool paper weight.
Was listening to Brian Cox the other day and he was saying that the universe is essentially "flat" (I think). Does anyone know anything about that? I always assumed it would be in some way spherical. With us at the epicentre*. * Just kidding on that last sentence. :) |
Re: Spaceships and astronomy
Originally Posted by Shard
(Post 12639684)
That is a very cool paper weight.
Was listening to Brian Cox the other day and he was saying that the universe is essentially "flat" (I think). Does anyone know anything about that? I always assumed it would be in some way spherical. With us at the epicentre*. * Just kidding on that last sentence. :) The other thing which has helped me understand and visualize the "shape" of the universe is to think of space as analogous to the surface of a balloon, where everything moves away from everything else as the balloon inflates. The image of an expanding balloon also lends itself to visualizing an allegory of how there isn't a "centre" of the universe away from which everything is expanding. |
Re: Spaceships and astronomy
Originally Posted by Pulaski
(Post 12639699)
"Flat" in the context of astrophysics just means everything is, more less, evenly distributed in all directions.
The other thing which has helped me understand and visualize the "shape" of the universe is to think of space as analogous to the surface of a balloon, where everything moves away from everything else as the balloon inflates. The image of an expanding balloon also lends itself to visualizing an allegory of how there isn't a "centre" of the universe away from which everything is expanding. Maybe "flat" is the wrong word to describe "even distribution in all directions"? Basically, I don't geddit... I can imagine a "sheet" (plane) that expands with no specific center, but that would be relatively "flat" and then I would wonder why does it need to be 2 dimensional ? |
Re: Spaceships and astronomy
It's related to special relativity, topology, space time curvature, (what we normally consider spherical/curved), and mass density.
Not really 'flat' as we normally use the term, more of a condition of the universe. |
Re: Spaceships and astronomy
Originally Posted by Hotscot
(Post 12639706)
It's related to special relativity, topology, space time curvature, (what we normally consider spherical/curved), and mass density.
Not really 'flat' as we normally use the term, more of a condition of the universe. |
Re: Spaceships and astronomy
Originally Posted by Shard
(Post 12639702)
The balloon seems de facto spherical to me. ….
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Re: Spaceships and astronomy
Originally Posted by Shard
(Post 12639684)
Was listening to Brian Cox the other day
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Re: Spaceships and astronomy
Originally Posted by steveq
(Post 12639744)
Lizzyq worked out that she was in the same physics lectures with Cox when she read physics and electronics at Manchester around 1986. Doesn't remember him though.
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Re: Spaceships and astronomy
Originally Posted by Shard
(Post 12639873)
So she tells you ;)
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Re: Spaceships and astronomy
I was disappointed by the "first picture of a black hole". Despite much apparent excitement in the astronomical community, and several petabytes of data, it was, IMO, nothing more than an orange smudge.
I presume that at that distance stars are usually no more than points of light when viewed from Earth, so to create an image with such width is a technological achievment, but the results are underwhelming. :( https://cimg4.ibsrv.net/gimg/british...aa094d4532.jpg |
Re: Spaceships and astronomy
Originally Posted by Pulaski
(Post 12692392)
I was disappointed by the "first picture of a black hole". Despite much apparent excitement in the astronomical community, and several petabytes of data, it was, IMO, nothing more than an orange smudge.
I presume that at that distance stars are usually no more than points of light when viewed from Earth, so to create an image with such width is a technological achievment, but the results are underwhelming. :( and black holes are ipso facto, invisible, so you can't see them in visible light. This "image" was taken with radio telescopes all around the earth and added together with an incredible amount of v computer power to get even this - a technique you can't employ with optical scopes on a large scale, making the imaging telescope 8000 miles in diameter. It is a technical tour de force, that we have an image, and that the physical reality matches the theory did closely. The brightening at the bottom is predicted by relativity. |
Re: Spaceships and astronomy
Originally Posted by Shard
(Post 12639702)
The balloon seems de facto spherical to me.
Maybe "flat" is the wrong word to describe "even distribution in all directions"? Basically, I don't geddit... I can imagine a "sheet" (plane) that expands with no specific center, but that would be relatively "flat" and then I would wonder why does it need to be 2 dimensional ? Take a sheet of paper. Draw a triangle on it, using straight edges and stuff. The internal angles add up to 180 degrees. Now wrap that paper around a large toilet roll. The paper seems curved, but the angles of the triangle drawn on it still add up to 180 degrees. It's flat. Draw a triangle on the surface of a smooth sphere. The internal angles of that triangle will add up to more than 180 degrees. Not flat. I think that's it. I could be wrong. I'moften a figment of mu own imagination - never somebody else's... :( |
Re: Spaceships and astronomy
I was going to sketch this, but the best explanation I've found that I can point you at is Laurence Krauss' book
https://www.amazon.com/Universe-Nothing-There-Something-Rather/dp/1451624468 |
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