What Caused the Big Bang?

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Every astronomy textbook tells us that soon after the Big Bang, there was a period of exponentially accelerating expansion called cosmic inflation. In a tiny fraction of a second, inflationary expansion multiplied the size of the universe by a larger factor than in the following 13 and a half billion years of regular expansion. This story seems like a bit of a … stretch. Is there really any mechanism that could cause something like this to happen? What what we’re covering today – the real physics of cosmic inflation.

Hosted by Matt O'Dowd
Written by Matt O'Dowd
Graphics by Leonardo Scholzer
Directed by Andrew Kornhaber
Produced By: Kornhaber Brown

Dark Energy Playlist:

The Quantum Vacuum and Hawking Radiation Playlist

Most cosmologists buy some variation of the inflation hypothesis. It seems to very neatly solve some of the biggest questions in cosmology. Those being: why is matter and energy so smoothly spread out across the entire observable universe? And why is the geometry of the universe so flat? Neither should be expected unless the universe expanded much more rapidly early on. We explored these problems in an earlier video – worth a look if you really want to get inflation. Another problem fixed by inflation is the absence of magnetic monopoles – strange particles predicted to have been produced in the early universe. We’ll come back to those another time.

Big Bang Supporters:

Anton Lifshits
David Nicklas
Fabrice Eap
Juan Benet
Justin Lloyd
Morgan Hough

Quasar Supporters:

Mark Heising
Mark Rosenthal
Tambe Barsbay
Vinnie Falco

Hypernova Supporters:
Chuck Zegar
Danton Spivey
Donal Botkin
Edmund Fokschaner
Hank S
John Hofmann
John R. Slavik
Jordan Young
Joseph Salomone
kkm
Mark Heising
Matthew
Matthew O'Connor
Syed Ansar

Gamma Ray Burst Supporters:

Adrien Hatch
Alexey Eromenko
Andreas Nautsch
Bradley Jenkins
Brandon Labonte
Carlo Mogavero
Daniel Lyons
David Behtala
DFaulk
Dustan Jones
Geoffrey Short
James Flowers
James Quintero
John Funai
John Pollock
Jonah
Jonathan Nesfeder
Joseph Dillman
Joseph Emison
Josh Thomas
Kevin Warne
Kyle Hofer
Malte Ubl
Mark Vasile
Nathan Hitchings
Nick Virtue
Paul Rose
Ryan Jones
Scott Gossett
Sigurd Ruud Frivik
Tim Jones
Tim Stephani
Tommy Mogensen
Yurii Konovaliuk
سلطان الخليفي

[The_Angry_BeEconomist]

I would be lying if I said I understood what this guy is saying, and yet I continue to watch these videos.

[Bokarma]

Matt O'Dowd is such a great writer AND presenter. You can tell he really cares about the science and delivers his knowledge very elegantly

[joshbloom]

I teach a high school astrophysics class and I rely heavily on this series to boost my understanding and help me translate difficult concepts to my students. I’m a much better - and more educated - teacher. Thank you Matt O’Dowd.

[JoelMurphy]

"The universe is expanding. That should help ease the traffic."
Steven Wright

[huntingteemo]

Ah, a new PBS Space Time Video!
My brain: please dont

[treadwell]

“This story seems like a bit of a STRETCH”. Nicely done.

[burtosis]

I believe the reheating phase is scientific proof the universe is only half-baked.

[kirillazarov]

"The Big Bang theory is a bit of a stretch."
Classy!

[jamieculp]

I'm normally kinda smart, but watching this I feel like Homer Simpson. "Can you repeat the part of the stuff where you said all about the things?"

[LuisFlores-ellq]

Man, do I love your cosmology episodes. BEST physics channel on Youtube.

[Tore_Lund]

A shirt? He's going on a date right after the shoot!

[ASLUHLUHCE]

Yeah... this was difficult to understand at 5 am. I'll rewatch some other time.

[sebastianelytron]

I was thinking about what the universe was like before the Big Bang.



Nothing came to mind.

[johnb]

Well done. You are becoming an expert in interpreting these concepts without the math and scientific lingo. Thanks and to all the staff who support you.

[chrismcgarry]

10:04 That "Inflaton Field" Illustration just explains so many concepts of Cosmology & QFT! Mind-blowing stuff!

[chrisfromnoosa]

Matt O'Dowd you are up there with the best of fortunate to have you (so to speak) and more than a few of us are proud of you. Keep up the good work and thank you.

[Ouvii]

I love how both Fermilab and Space time are using phase transitions of water to describe cosmology or neutrino physics concepts. It makes the material really easy to grasp.

[Chuck_Huckler]

This episode was just "But that'll have to wait for another episode" - The Episode

[stayfrost]

8:45 - Turn on English Captions. PLEASE! xD

[wenaolong]

Bravo. Aristotle would be proud and astonished at the progress made since his first volumes of physics were compiled.