If you were to fly in a straight line, faster
than the speed of light, directly toward the
edge of the universe… you'd eventually end
up back where you started, because there IS
no edge.
Take 5 seconds and think about that.
Howdy people who want to have their mind blown.
Trace here for DNews.
This one was super fun to research.
A study came out recently in Physical Review
Letters, stating that cosmology was safe;
the universe was, indeed, isotropic.
I know you're relieved.
When the ancient Greeks looked up at the sky,
they realized the universe could be one of
two things, infinite -- stretching forever
in every direction, or finite -- with an edge.
When Newton described the law of gravity,
he thought about this too, and figured it
must be infinite, because otherwise all the
gravity out there would have collapsed the
universe by now.
Then, Einstein assumed the universe was static
-- creating a cosmological constant to make
his math work.
But then, Edwin Hubble came along…
In 1925, Edwin Hubble was looking at galaxies.
He was a lawyer by training, but loved cosmology
and astronomy.
He got time on a telescope in California,
and began measuring the doppler shift of the
light coming from galaxies.
Doppler shift is why an ambulance or train
sounds different coming at you than after
it passes.
That frequency shift is measurable, and he
found every galaxy we could see was flying
away from us.
He realized space is expanding!
He published his findings in the Proceedings
of the National Academy of Sciences in 1929,
and holy crap.
Einstein called his cosmological constant
his "greatest blunder."
Mathematician Georges Lemaître solved Einstein's
equations in this expanding universe, and once
we realized it was expanding, we could assume
it started somewhere and thus, the Big Bang
was conceived!
This was (and is) huge, and only getting bigger.
Expansion pun!
Okay, so, if all that's true, and our universe
is expanding and isotropic what does that even mean?
Think of our universe as baking raisin bread.
If each of the raisins is a galaxy, as the
bread bakes, the dough rises, and the raisin-galaxies
expand away from each other along with the
rise, in all directions at once!
If this happens irregularly, the universe
is anisotropic -- like the grain of a tree,
it's "stronger" or tends to have layers, or
striations where it might expand faster or
slower.
Isotropic universes, like ours, they don't have
those.
They're consistent, smooth, homogenous, and
symmetrical… ours is all that.
According to Astronomer Phil Plait, it's expanding
at "74.2 kilometers, per second per megaparsec"
(plus or minus 3.6 kilometers) -- it's now called
the Hubble Constant.
"A galaxy 10 megaparsecs away," Plait wrote
for Discover Magazine, "would be moving away
from us at 742 km/sec" Basically, every million
years, galaxies are point-zero-zero-seven
percent farther away from each other.
Trust me.
That's really really fast.
And, thanks to dark energy, it's getting faster.
But that's a whole other story.
I'm sure you're thinking, okay cool, our isotropic,
infinite universe is expanding.
Fantastic.
Expanding into… what?
That's the complicated part.
The universe, by definition is all existing
matter, and space as a whole.
If the universe is infinite and homogenous,
then it's not expanding into anything, it's
just… expanding.
Think of it this way...
You're an ant, standing on a balloon of incredible
size. It's so big it seems flat from your perspective.
As the balloon continues to inflate, it's
expanding in every direction.
No matter which direction you look, the balloon
is getting larger!
No matter how fast or far you run, you'll
eventually end up back where you started.
Like a video game from the 1970s. You go off the
screen, and you just come back on the other
side.
This is how astronomers look at the universe,
but it's not a 2-dimensional surface of a
balloon, it's a three-dimensional region,
expanding in a 4-dimensional universe in every
direction at once.
No matter where you go, you'll eventually
end up still in the universe, and back where
you started.
This is also why there's no center of the
universe.
Where would the "center" of the balloon's
surface be?
Knowing the universe is expanding, and how
fast, and that it's isotropic, keeps cosmology,
Einstein and hundreds of other scientists'
theories safe, for now.
But as we learn more, and measure deeper and
deeper into the universe, who knows what we're gonna
see.
If you want to know more crazy complicated
science, how about the butterfly effect?
It's not what you think it is.
Watch this video to find out more.
I can't get enough of these awesome science
topics, do you have a science question?
Ask us below or go over to our subreddit r/dnews
to find out more. You can also subscribe both there and here
and thanks for watching.
