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Astronomical Illusion - Earth is the center of the universe by William Huggins - Tue, 19 Jun 2018 17:15:11 EST ID:6aIwEr35 No.57311 Ignore Report Quick Reply
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This is from a video series I saw long ago and it described a general illusion that is responsible for the Earth being seen as the center of the universe.

Like they say that in a few million/billion years the sky is going to be completely dark because the stars are moving away from us. But this is just an illusion from our vantage point. We're also moving away from them but we can't see it, only visualize it.

The way I remembered in the video was very clever and simple.

It was like rows and columns of 4 dots:

. . . .
. . . .
. . . .
. . . .

And it had like a clear paper with one dot in the middle. And as the transparent paper moved, the dot moved relative to the stationary background and you could see how the center of the dot in the transparent paper stayed stationary as the rest moved away.

I'm probably not explaining it right because even that doesn't make sense to me but maybe it's enough to go on for one of you out there
Pierre-Simon Laplace - Tue, 19 Jun 2018 17:47:16 EST ID:457vC2+I No.57312 Ignore Report Quick Reply
Well, to say it's an illusion is kinda misleading. The size of our hubble volume is receding even now because of the expansion of space, diminishing the number of stars from which light will ever reach our planet. But it's not an 'illusion' the light beyond the cosmic horizon really is trapped in such a way that it can never get to us. By the time all stars have receded from our hubble volume, when our hubble volume is the size of our solar system, of course those other stars will still exist, but we will in a very real, non-illusory sense, be trapped with the light of our star in a void where the nearest other star is literally impossible to reach.

So in a very real sense the earth is the center of the universe, because it is the center of our hubble volume, and so the limit for all potential voyages from earth is, in a cosmic sense more real than voyages from a particular place on earth to another point on earth, constrained to a sphere with earth at the center.

Unless FTL is possible, which is the only way to go beyond the 'illusions' that the speed of light and expansion of space force us into
Thomas Henderson - Wed, 20 Jun 2018 10:08:09 EST ID:6aIwEr35 No.57313 Ignore Report Quick Reply

Thanks for the explanation but the illusion I was referring to was the fact that astronomers before would always postulate that Earth was the center of everything (that is, stationary) and everything else is moving away or moving around us.

But in reality, Earth is moving as well and isn't actually stationary.

The illusion is that Earth is just used as a stationary anchor point for our perspective because we need a relatively stable point to base our calculations on. Like the same way we arbitrarily chose the weigh of a kilogram and now use that to conceptualize weight relative to one another.

But because of modern technology, we can visualize the universe more conceptually without putting Earth at the center.
Henry Draper - Wed, 20 Jun 2018 22:42:36 EST ID:457vC2+I No.57314 Ignore Report Quick Reply
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Astronomers certainly are aware of the motion of our solar system and account for it in their calculations when it is relevant, including calculations of expansion and redshift. I agree I wish popularly available star charts included depictions of the direction of motion and speed of stars so people can visualize what is going on better, but if, as a matter of principle, we stop using earth as the reference point, over time they will become off center with the physical hubble volume, the universe-lifetime light sphere of earth, which is obviously centered here. Once we are an interplanetary species, we will obviously need new definitions, and for most practical purposes the difference won't matter much.

How would you feel about using the center of the galaxy (either its gravitational center or the supermassive blackhole Sag A*) as our reference center point? That wouldn't differ too much from our visible observations, and seems the most convenient.
Annie Cannon - Wed, 27 Jun 2018 15:30:26 EST ID:6aIwEr35 No.57319 Ignore Report Quick Reply

I'm not against using Earth or whatever as a reference.

I was just intrigued by the natural phenomena that we see ourselves as the center of things when it's a fallacy of perception. And I remember the same phenomena existed in astronomy until the copernican revolution

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