Full transcript
0:00even back then they knew that hey it was
0:03round and there was people actually
0:05arguing that maybe just maybe the earth
0:11was in the center at the time everyone
0:13really thought earth was the center of
0:15the universe but there were people
0:20actually making arguments saying that
0:23hey maybe the Sun was the center they
0:26thought it made more sense but they were
0:28more or less shouted down they were told
0:30nope it didn't make sense and there was
0:32some convincing arguments that they used
0:35at the time one being that hey if we if
0:40the Sun is the center and we were going
0:42around it one of the things they talk
0:44about is the idea that we feel it we'd
0:47somehow feel it and one reason you could
0:50think about this is look if you're
0:51running through a field well you feel
0:55the wind pushing back against your face
0:57well they said the same thing obviously
0:59if it was going through space then we
1:02should be feeling the wind what they
1:05didn't realize at the time was of course
1:06that there is not really matter out
1:08there not of any considerable amount so
1:11there's nothing to create a force on us
1:13and we're talking more about forces
1:15later but they also thought that look if
1:20we were rotating around the Sun then the
1:24stars we see should shift it they should
1:28go through this idea of parallax where
1:30the stars that are close to us should
1:33seem to shift relative to even further
1:36stars and this image hopefully kind of
1:39shows it if you're looking at from one
1:41vantage point to another so if we're
1:43rotating around the Sun and then we're
1:45looking at it from one side of the Sun
1:47to the other then what we see how the
1:50stars nearby should shift what they're
1:54lined up with so if you're looking from
1:56here and looking right at the star you
1:57see you would line up with a blue and if
2:00you were looking over here it would seem
2:02to line up in front the red and I
2:04actually thought I would show a couple
2:05demonstrations of this as well so let's
2:08turn on the camera
2:10No hi one simple little way of
2:13demonstrating this something you can do
2:15right now with me in fact you should is
2:17put up a finger I always love to make
2:20the joke then literally asking you to
2:21raise a finger well put out your finger
2:24and now look at where your finger lines
2:27up with something farther away in my
2:29case right now it's in front of a window
2:30and what you gonna do is first close one
2:33eye close one eye and look at it from
2:35one eye only and see where it's lined up
2:38in front of now switch eyes so close the
2:43other open the other and you should have
2:45seen your finger switch it looks like
2:47it's lined up with a very different
2:48thing
2:49this is parallax and actin looks kind of
2:52crazy when you're just saying they're
2:53blinking but it's a great demonstration
2:56of parallax cuz it will shift and you
2:58know you're not moving your finger and
2:59actually I'm gonna show one more
3:01demonstration that it's very similar to
3:04the image we're just looking at and what
3:05I'm gonna do is actually line up my
3:07finger basic I'm gonna do the parallax
3:09right here so my finger lined up in
3:10front of this window now if I move the
3:14camera so I'm not gonna move my finger
3:15please bear with me believe me so as I
3:17move the camera you can see it seems
3:20like it's moving like my fingers moving
3:23it's not again I assure you I'm not
3:26actually moving my finger but it looks
3:28like it is because it's where it lines
3:31up relative to more distant objects he's
3:34changing so that's the idea of parallax
3:40so back to here and that's the thing
3:43they thought fine if the earth wasn't
3:47the center and stars are at different
3:48points and we're moving then we should
3:50be seeing parallax we should be seeing a
3:52para lactic shift stellar parallax stars
3:55should move relative to more distant
3:58stars and this was a great argument and
4:01completely right this was a hundred
4:03percent correct this was a great
4:05argument to make but the thing is we
4:09know obviously that the earth is moving
4:10now and they weren't noticing stellar
4:13parallax but the reason was because it
4:16was so so small they couldn't comprehend
4:19the kind of distances we were talking
4:20about just how far away these stars are
4:23so
4:24when we look now if we look with the
4:26sensitive enough instruments we look
4:27with a good telescope we can see and
4:29notice a slight parallax shift of our
4:32stars relative to more distant ones but
4:34it's incredibly small it's very very
4:37very very difficult to see except for
4:38extreme cases so that's why they still
4:43rejected this sun-centered model because
4:46they didn't I mean there's a lot of
4:48reasons but that was the most convincing
4:49actual proper argument because hey you
4:52should see the stellar parallax shift
4:54and guess what we're not so where guess
4:57we're not moving but of course again we
5:01know that we are