Space DOES NOT Expand Everywhere

Sign Up on Patreon to get access to the Space Time Discord!

Space is big, and it’s getting bigger. But where does all that new space actually come from? And is it popping into existence all around you right now? Is that why the remote control is always further away than I thought?

Check out the Space Time Merch Store

Sign up for the mailing list to get episode notifications and hear special announcements!

Hosted by Matt O'Dowd
Written by Matt O'Dowd
Post Production by Leonardo Scholzer, Yago Ballarini, Pedro Osinski, Adriano Leal & Stephanie Faria
GFX Visualizations: Ajay Manuel
Directed by Andrew Kornhaber
Associate Producer: Bahar Gholipour
Executive Producers: Eric Brown & Andrew Kornhaber
Executives in Charge (PBS): Adam Dylewski, Maribel Lopez
Director of Programming (PBS): Gabrielle Ewing

Spacetime is produced by Kornhaber Brown for PBS Digital Studios.
This program is produced by Kornhaber Brown, which is solely responsible for its content.
© 2022 PBS. All rights reserved.

Special Thanks to Our Patreon Supporters

Big Bang Supporters
Adam Hillier
Bryce Fort
Mark Evans
David Taiclet
Daniel Alexiuc
Peter Barrett
David Neumann
Charlie
Leo Koguan
Sandy Wu
Ahmad Jodeh
Alexander Tamas
Morgan Hough
Amy
Juan Benet
Vinnie Falco
Fabrice Eap
Mark Rosenthal
David Nicklas

Quasar Supporters
Alex Kern
Ethan Cohen
Stephen Wilcox
Christina Oegren
Mark Heising
Hank S

Hypernova Supporters
William Bryan
Gregory Forfa
Kirk Honour
drollere
Joe Moreira
Marc Armstrong
Scott Gorlick
Paul Stehr-Green
Adam Walters
Russell Pope
Ben Delo
Scott Gray
Антон Кочков
John R. Slavik
Mathew
Donal Botkin
John Pollock
Edmund Fokschaner
Joseph Salomone
chuck zegar
Jordan Young
Daniel Muzquiz

Gamma Ray Burst Supporters
Thomas Tarler
bsgbryan
Sean McCaul
Carsten Quinlan
Susan Albee
Frank Walker
Matt Q
WhizBangery
Avi Yashchin
MHL SHS
Kory Kirk
Terje Vold
Anatoliy Nagornyy
comboy
Brett Baker
Jonathan Conerly
Andre Stechert
Ross Bohner
Paul Wood
Kent Durham
jim bartosh
Nubble
Chris Navrides
Scott R Calkins
The Mad Mechanic
Ellis Hall
John H. Austin, Jr.
Diana S
Ben Campbell
Faraz Khan
Almog Cohen
Alex Edwards
Ádám Kettinger
MD3
Endre Pech
Daniel Jennings
Cameron Sampson
Pratik Mukherjee
Geoffrey Clarion
Nate
Darren Duncan
Russ Creech
Jeremy Reed
Eric Webster
David Johnston
Web Browser
Michael Barton
Christopher Barron
James Ramsey
Mr T
Andrew Mann
Isaac Suttell
Devon Rosenthal
Oliver Flanagan
Bleys Goodson
Robert Walter
Bruce B
Simon Oliphant
Mirik Gogri
Mark Delagasse
Mark Daniel Cohen
Brandon Lattin
Nickolas Andrew Freeman
Shane Calimlim
Tybie Fitzhugh
Robert Ilardi
Eric Kiebler
Craig Stonaha
Martin Skans
The Art of Sin
Graydon Goss
Frederic Simon
Tonyface
John Robinson
A G
David Neal
Kevin Lee
justahat
John Funai
Tristan
Bradley Jenkins
Kyle Hofer
Daniel Stříbrný
Luaan
Cody
Thomas Dougherty
King Zeckendorff
Nick Virtue
Scott Gossett
Dan Warren
Patrick Sutton
John Griffith
Daniel Lyons
DFaulk
Kevin Warne

[Psychonaut]

Out of all the physics channels I understand nothing about, this is my favorite

[pixartist]

You always pick up on the "but why" questions that pop into my head when thinking about these things. I love it.

[EduardoLauandeTeixeiradeSouza]

Every episode of PBS Spacetime is for me a physics or class. the only difference is that it uses as little math as possible without sacrificing clarity and precision. Without demerit of other programs here in Brazil or abroad, PBS SpaceTime is my favorite channel.
Thank you all a lot!!

[jacobsaintjames]

Happiness is being able to wrap my brain around an episode of PBS Space Time.

[Ormaaj]

The alien race simulating our universe had to do a memory upgrade duh. Last time they tried inserting new memory they got massive inflation. Solution: gradually interleave new bits amongst the old bits. The only side-effect is red-shifting of distant galaxies, but probably no one will notice.

[spacedragon]

Actually, this video answeres some questions I've had since I was 16 or so. Never could this questions be answered by anyone I asked... Until now!
I really love this channel for explaining phyiscs in an understandable way but at a level high enough for me to be satisfied. Thanks a lot Matt!

[thedarkercarter]

So the "pinched gravity" part is probably the thing that I've been missing in understanding the expanding universe. So I have to give a thanks for that. Like I knew that space was expanding more in the far reaches but nothing seemed to explain WHY it wasn't happening in the galaxy. So along with that and the Metric I now have a much better understanding!

[paulembleton]

After listening to Roger Penrose talking about maximum entropy being the initial state of our universe, and its ultimate state which perhaps leads to another big bang, I imagined the universe as a zip file that can be infinitely unzipped, but the file size doesn’t grow it becomes more detailed, and this additional detail gives the impression of expansion for anything occupying it. From the universe’s perspective it isn’t expanding at all since it has no reference, either spatially or temporally. No new spacetime no stretching.

[brutussmithicus]

This is the most accessible episode so far - I may recommend it to non-scientist friends. The concepts were more intuitive than most other episodes & the pacing meant that I didn't need to hit pause or rewind so often. Thank you so much for taking the time to create this awesome series, you have explained the concepts that eluded me during my late 80's quantum chemistry lectures :-)

[jeff]

This video answers multiple questions that I've been wondering about for years and presents them in a way that shows how they are interconnected. (It even incorporates a discussion of Hawking radiation and sub-Planck-length phenomena.) Thank you for the clear presentation! I am amazed at how many of my questions actually had answers and even more amazed that they could be explained in language that I could understand.

[raurora]

This is one of your best videos. I think this is something that anyone who has tried to have a physical understanding of an expanding universe has thought about. Incredibly well explained.

[KjV]

0:00 Finally, he says an explanation I understand.

[joymoding]

You guys must be mind readers up there, because this topic has been on my mind for a while now. The idea that the Planck length isn't an actual quantization of space, but rather a limit on energy-based measurement in an infinitely divisible spacetime is the only conclusion I've been able to come up with as well. But if it's true, it's immensely fascinating, because it implies there is some "existence" of space that is inaccessible by our current methods of measurement. But if this sub-planck space truly exists, then it must interact with the universe in some way (that's what it means to exist), which means there's some REAL thing out there that is capable of defining and describing space at smaller scales seemingly forever. Love all this stuff and the phenomenal videos that you produce. Keep it up!

[MrARock]

Historians: This is a challenging and difficult time to be alive.

Cosmologists: Actually, this is an extremely fortuitous time to be alive.

[mihiru]

"Gravitational field isn't something that lies on top of the fabric of spacetime, gravitational field IS the fabric of gonna get a t-shirt made with that quote!

[markrothenbuhler]

Here is PBS Space Time expanding our understanding and knowledge everywhere. Thanks, Matt!

[Crackhonos]

Question: Lets imagine whole universe contains only two stellar mass stars. What the distance between them would need to be, in order for new space to be created between them ? Or how would we calculate distance between two objects in order for them to no longer be gravitationaly bound ?

[goingballisticmotion]

This is the raisin loaf analogy. Bake a loaf of raisin bread. The bread expands and the raisins move apart, but each raisin keeps it size. So intergalactic space is the bread and galaxies are raisins.

[AstroRamiEmad]

"Space, " [the Hitchhiker's Guide] says, "is big. Really big. You just won't believe how vastly hugely mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space. Listen . . ."

[JubilantJerry]

Basically: the edges of objects that are gravitationally bound are "moving inward" relative to the grid that defines the expanding space, such that the object never changes size and the balance is never upset. This balance is lost if the dark energy density changes, which is why the big rip requires dark energy to become stronger over time.