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The Unruh Effect | Space Time

PBS Space Time - 2018-04-04

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Worried about black holes? Consider this: Every time you accelerate - you generate an event horizon behind you. The more you accelerate away from it the closer it gets. Don’t worry, it can never catch up to you, but the Unruh radiation it generates sure can.

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Previous Episode:
The Andromeda-Milky Way Collision

Around the same time that Stephen Hawking was demonstrating the existence of the black hole radiation that would bear his name, three other researchers, Stephen Fulling, Paul Davis, and William Unruh, were looking at an effect that now seems eerily similar. They were independently studying how the nature of quantum fields appears to change depending on whether or not an observer is accelerating. They found that simple act of acceleration cuts off your causal access to a region of the universe. It creates a type of event horizon. As we saw in our episode on horizon radiation, the presence of horizons distorts the quantum vacuum in a way that can create particles. 

Hosted by Matt O'Dowd
Written by Graeme Gossel and Matt O'Dowd
Produced by Rusty Ward
Graphics by Grayson Blackmon
Assistant Editing and Sound Design by Mike Petrow and Linda Huang
Made by Kornhaber Brown (www.kornhaberbrown.com)

Classical analogue of the Unruh effect
Leonhardt, Griniasty, Wildeman, Fort, & Fink

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antiisocial - 2019-08-28

The Rindler Horizon confirms that I really CAN run away from all my problems, as long as I keep running faster and faster!

takeshiC1 - 2018-04-17

No matter how many times I play this vid, the understanding never catches up

timwins31 - 2019-12-10

Same here, its the 1st Space Time vid that I can't wrap my head around. I just don't have the background or maybe just not enough ability to understand it theoretically. I dunno. But I don't get it. I'm gonna sit here and watch it a good 20 or 30 times more and see if it takes. . .

Kyle Watson - 2020-02-01

It's big word time

CowboyChemist - 2020-02-03

Lol love these comments

Dziaji - 2020-02-08

Because the video is garbage.

Αλεξανδρος Πατσαλος - 2020-03-11

Its the pbs spacetime event horizon

tewt on me - 2019-05-04

"The very existence of particles is observer-dependent." Me, arguing with my physics prof about why I got the question wrong.

shaun humphreys - 2020-02-03

@Shawn measurements including observation do collapse wavefunction superpositions. a fact remarked by all the greatest quantum physicists, and this is the ultimate conclusion of quantum mechanics if all of the phenomena is fully accepted.without having various philosophical biases like Einstein had against it.

Shawn - 2020-02-04

@shaun humphreys measurements such as a photoreceptor or a polarized lenses collapse the wave function not observations.

shaun humphreys - 2020-02-04

@Shawn observations do collapse the wave function. observation are a measurement. any measurement collapses the wave function, including that of a sentient or non sentient life form.

shaun humphreys - 2020-02-04

​@Shawn regardless even of sentience, the act of measurement is an act ob observation. hence an observe dependent universe, as the majority of the great quantum physicists and the eminent physicist john archibald wheeler have maintained-hence the
participatory universe model'. indeed the model of any first class universe is that is participatory. the wave function may not even collapse. the hugh everitt many worlds interpretation holds that all the possible outcomes occur in parallel worlds, so reality decoheres/splits into many branches each time. a clever experiment to test this proposed by physicist Rainer Plaga in the nineties was conducted and gave a firmly positive result for the many worlds interpretation for the wave function. Also the mathematics of quantum mechanics fits most neatly with this interpretation so i lean in that direction.so called retrocausal quantum experiments such as post-selection which appear to be changing the past go against the one measurement rule of copenhagen interpretation and violates causality, and creates time paradoxes. Instead what would be happening is to prevent a time paradox, reality decoheres during the attempt to change the past of a particle such as a photon or electron-it decoheres into a parallel universe copy of the present with an altered past-that is in the new copy of the past, the past history of the particle affected in the retrocausal experiment will be changed so that it is line with what the retrocausal experiment did to the particle's past. and as the new parallel copy is discontinuous to the original reality branch, there are no paradoxes, and entropy is not involved as the parallel universe copy did not exist before the retrocausal event in the experiment. So this attempt to take a more common sense approach to the wave function which seems intuitive, is not always correct. .

Alleyway Mind Hook - 2020-03-14

@shaun humphreys These are honestly the most coherent comments in this thread by a longshot. Cheers for the valuable info!

KungKras - 2019-06-08

"Are you worried about black holes?"
Finally a commercial that gets me!

Αλεξανδρος Πατσαλος - 2020-03-11

You sir, have earned a banana🍌

Tom Meyers - 2019-03-06

The Ruhroh effect. Every scary creature is just some guy in a mask.

unsub me - 2019-08-07

Im zoinked

antiisocial - 2019-08-28


苗媌緢喵瞄描 - 2019-10-28

ohhhhh, in a mask eh, so just like the Hong Kong "freedom" fundamentalists

theRealPlaidRabbit - 2020-01-07

And he would have gotten away with it too,. if it weren't for those meddling kids!

Kyle Towers - 2020-01-18

@苗媌緢喵瞄描 - Congratulations! You win the award for "Most Obvious Chinese Government Troll".

GothicGamer2012 - 2018-08-16

These videos help me balance my ego. Whenever I feel unrealistically smart, I come here and am put right back in my place. Average.

I understand some of it, but some of it is just gibberish to me.

Dziaji - 2020-02-08

It’s gibberish garbage.

Elliot McGee - 2020-03-07

Sounds like someone didn't understand it

Αλεξανδρος Πατσαλος - 2020-03-11

@Elliot McGee u think?

Pan Darius Kairos - 2018-04-05

The universe is a very Unruhly place

J T - 2018-09-23

fucking hell

Lennox Xonnel - 2018-12-01

Why is this not the top comment I don't even know

DC Perry - 2018-12-23

Very deWitty

Wizbro - 2019-01-15

I shit myself laughing at ur comment!

Carl Bailey - 2019-08-30


Matt C - 2020-01-08

My new catch phrase is "I have to jet, but not too fast, lest I combust in a Fulling-Davies-Unruh bath"

Radonatos - 2020-02-11

"Sorry boss, I was working so fast that your words never came past my Rindler horizon."

Mega Glub - 2019-06-12

I read the title as "the unbruh effect"
what has the internet done to me

Fadel_novalhidayat novalhidayat - 2019-06-13

I would like to report bruh moment

barbarian jk - 2020-01-23


Αλεξανδρος Πατσαλος - 2020-03-11

Bruh momentum

PJ Vis - 2018-04-05

"A space-time diagram has two axes, space and time."

Thanks, I learned something new.

Feynstein 100 - 2018-04-05

0:00 "(casually) Are you worried about black holes?" Best opening ever 😂😂

EmpireBuilder - 2019-04-19

Today: Cop pulls you over for speeding
Tomorrow: Cop pulls you over for accelerating too fast.

Daniel Andersson - 2018-04-04

"Degree Kelvin" twitches <3

Oliver Simonaitis - 2019-06-21

i thought the thumbnail said the “bruh effect”

iinRez - 2019-05-29

Slowly but surely, I am beginning to understand.

Thank goodness for PBS Space time.

Demetrick Louis - 2019-04-21

So... the Unruh Radiation is the speed force?

DJBsLectures - 2018-04-04

"It's been worked out with math and everything"

Ville Walveranta - 2018-08-28

It's the "everything" from "Life, the Universe and Everything".

Wizbro - 2019-01-15

Good quote. Mind if I quote u on that?

Grok Effer - 2019-01-28

Math and everything was my least good subject in school. The Everything part was OK, but the Math not so much.

thiefofheartss - 2019-02-18

@Ville Walveranta "Life, Unruh and Everything".

jim twisted - 2019-08-12

I’m convinced now.

tacopacopotato - 2018-04-08

physics is a trip. Every time I watch one of these I'm reminded that our conception of reality is so incredibly comically limited. Shit is eye opening, humbling, scary, awesome; I'm sure theres plenty more words. Thanks for these videos, accessibility of this knowledge is invaluable.

Xak Nitram - 2018-04-05

"Are you afraid of spiders? Here, hold mine."

TheFLOW1978 - 2018-04-05

So, that silhouette cloud, the road runner leaves behind, is a representation of the Unruh effect?

Michael Reynolds - 2018-05-08

"Chief, when will the warp drives be functional again we must make it to star base 23 immediately."
"Right...carry on."

Jacques Stoop - 2019-09-25

Michael Reynolds
ok now these scientists must be fucking with us, what’s next? The Ooga Booga effect?

Star Dorminey - 2020-02-28

@Jacques Stoop бог in Russian means "God," and любовь means "Love." so the surname Боголюбов I think means something like "God-fearing," though in this context "For the love of God!" fits the complexity of particle horizons better.
Disclaimer: I got a B in Russian.

Leo - 2019-01-15

"Bro did you just fart?"
"Nah bro that's just my Unruh Radiation"

Αλεξανδρος Πατσαλος - 2020-03-11

Okay, let's be honest, how thought that the title said "the bruh effect"

Singing Tallit - 2019-06-12

You can outrun the butterfly effect as long as you are accelerating!?

Judah Rosen - 2019-10-12

that would mean you could out run causality

Arman Galoyan - 2020-01-31

@Judah Rosen pretty sure the c in e=mc2 stands for causality, as in, the speed of causality. light just goes as fast as change as it has nothing weighing it down

WhimpyPatrol - 2019-07-23

I always knew my mind was in hyperdrive; I didn't catch anything he was talking about.

Αλεξανδρος Πατσαλος - 2020-03-11

Me when i realised this episode had diagrams: bruh effect

AvyScottandFlower - 2018-04-05

At first I thought the character in the red suit was Stephen Hawking..

Yes, I'm going to hell

Davin Young - 2019-01-29

Just rewatched after watching a video on quantized inertia. Are you coming back to this topic?

nischal dhungana - 2019-01-30

Me too do have some any suggestions to explore more about quantized inertia? The original paper was way to hard for me understand.

Drew Schmaltz - 2019-02-04

Same boat. I need someone to talk me down from quantized inertia being the answer to a lot of current unknowns.

jack mack - 2019-02-15

I too would appreciate more on quantized inertia. Thanks in advance. Peace through culture; prosperity through science.

Paul Francis - 2020-01-22

I've been afraid to leave my chair for 2 years now.

Madness by Design - 2018-04-04

I'm going to go get a burrito. If I get pulled over for speeding on the way back, I'll just tell the cop I'm trying to generate enough Unruh radiation to keep my burrito warm! Finally, a practical use for science!

Marrethiel - 2019-02-08

@SirVixIsVexed Actually the cop would not have seen the Unruh radiation and so would just book you.

SIX-SH00T3R - 2019-06-17

"Finally, a practical use for science!" lol

NothingMaster - 2019-08-10

To keep your burrito warm using Unruh radiation you would need to keep accelerating to incredible speeds, at which time it would be highly unlikely that any police car could catch up with you, unless he too was using some truly funky fuel. Of course, if that ever happens then you’re in far deeper waters than having to pay for a traffic ticket. Yes, I’m dense, I take all lighthearted hypothetical comments on YouTube seriously. That’s tough, as the music reacting Shaq dude might say.

Derek H. - 2019-09-06

"But I had to speed in the car pool lane officer! If I slowed down, my Unruh passenger would cease to exist!"

Ghislain Bugnicourt - 2020-03-03

To be fair you could be accelerating and still stay below speed limits as long as you're breaking half the time, since breaking is accelerating. Not a smooth drive though.

Light Studios - 2018-04-05

I look forward to the day when I can watch an entire Space Time episode and just go "Yes, of course".

thedeemon - 2018-04-05

That's really possible if you just read and understand one book by Roger Penrose - https://en.wikipedia.org/wiki/The_Road_to_Reality

Dr Deuteron - 2019-08-08

it is possible, but you're going to have to do some homework problems. You can't passively soak it all up.

T33K3SS3LCH3N - 2019-09-18

"U coming, I got 🍌" - guys to their girlfriends

zapleaf - 2019-06-16

I was very lost for the entirety of the video. Love it.

Girish BB - 2020-02-05

9:45 my teacher thought we should never use degree for Kelvin

joki boy - 2018-04-04

This video left me more stupid.

Cory Mck - 2018-04-09

I had to leave and watch 6 videos just to understand this one. It feels like homework, but nobody ever said quantum physics was easy

Limi V - 2018-07-19

The more you know, that more you realize how much you don't know

Adrian Tufita - 2018-07-25

This theory is way to complex for an average human to comprehend. This youtuber isn't a scientist,so...ignore him.

Limi V - 2018-07-25

Maybe you should check the facts before deciding who's a real scientist and who's not. From the channel's About page:

Matt O'Dowd spends his time studying the universe, especially really far-away things like quasars, super-massive black holes, and evolving galaxies. He uses telescopes in space to do it. Matt completed his Ph.D. at NASA's Space Telescope Science Institute, followed by work at the University of Melbourne and Columbia University. He's now a professor at the City University of New York's Lehman College and an Associate at the American Museum of Natural History's Hayden Planetarium

Kyrlics - 2019-09-04

@Adrian Tufita its not complexity that makes it hard. It's difficulty

Ken Munoz - 2018-04-05

This is the first time I’ve ever heard this explained in a manner from which I could understand... and I am a truck driver! Great video many thumbs up!👍🏽

Maddin1313 - 2018-04-05

"The existence of particles is observer dependent"
Ooh, I like that one.

AcidMist - 2019-03-15

4:12 Wodn't I see him when the light from him enters my past light cone?

White Night - 2018-08-08

Everythings moving, Moving where," Towards the End.So wouldn't it be Different If they were going to The same point. And Why ?

Dennis Haupt - 2018-04-04

first the delayed quantum eraser, now this. the universe is mocking us in various ways depending on how we look at it.

Alter Ego - 2019-08-17

The Unruh ("unrest" in German) effect is aptly named.

The Things - 2020-01-07

This explains why oneness can be achieved through meditation when all quantum field frequencies are uninhibited through lack of acceleration

dylan cross - 2019-05-11

He lost me at Boguluviob transformation 😂

Astariol - 2019-05-27

dylan cross I thought I was smart until he said that. Next came Hawking Derivation and I realized knew not a single fuck about what's going on

sloop - 2018-07-19

In english next time please.

Exterm inatus - 2019-12-17

"Leads to the creation of particles in the accelerating frame"

Everything in the universe, relative to everything else, is accelerating, whether spacetimeitself or one object to another, in some way shape or form.

Maybe the Universe exists because of this, everything just intertwined? What's that thing called where you're on the verge of explaining some idea or concept but don't have the intelligence or lack the words and concepts themselves to explain it?

The level of entanglement that is reality sometimes keeps me up at night :(

What is all this. Why are atoms and quarks just empty space and how can vibrations in separate intermingling fields coalesce to create....all of this?

Ugh. Frustration. And to think I'll never know before I die.

Tlowief Kcalb - 2018-04-05

Just FYI...the word "Strahlung" is German for "radiation", so when you said "Bremstrahlung radiation" that literally meant "Bremradiation radiation" (in German you can put two different words together to form a new one and it still makes sense), soo...idk if someone got the translation wrong or if physicists just suck at naming things.
Just wanted to point that out. Byee

khhnator - 2018-12-30

physicists do suck at naming things

Wizbro - 2019-01-15

Fucking hell! You're semantics changed my life! Since reading this comment I got married and had 2 kids!

attractor9 - 2019-02-17

yes in german you can make very long words and that's great. in english you have this thing too. but it is in english not consequent. and i think it is better to put words together when they build a new meaning. then you see the connection immediately in the writing. here is a really long one: bremsstrahlungsauswirkungsmessgerätevorrichtungshalter. i just made this up but in german it make full sense. here are the words separately: brems strahlung aus wirkung mess geräte vorrichtung halter (there are some "s" missing they are only in the whole word so you can better speak it). the meaning in english is: a holder for a device for the messurment of the impact of the break radiation.

L TR - 2019-04-08

I understand. I bristle every time someone says "with au jus" when talking of a sandwich. "Au jus" MEANS "with juice" in French, so when you say "With Au Jus" you are kinda saying "With With juice" and it sounds kinda redundant and dumb. Anyway, it happens when you cross language lines...so....just say you'd like your sandwich au jus, that would be the most intelligent way to cross the language line. Anyone calls you out, take 'em to school...

Dr Deuteron - 2019-08-08

@Kai A. Giermann brake, not break. (see: https://en.wikipedia.org/wiki/Brembo)

Rethinam Paramasivam - 2018-04-05

I love the the fact that they always end the episode by saying 'spacetime'

Pancho - 2019-02-19

Haha! That was a really funny ending. Thank you, Matthew! I really LOVE this channel.

Greger Olsson - 2018-04-04

PBS: "We need an infographic of a Rindler observer out of causal connection..."
Graphics Designer: "uhhm... you can have a monkey, mmkay?"

Michael Sommers - 2018-04-05

+Rubellite Fae
So "Old World monkey" is an out-dated term. Big deal. 'Catarrhine' is too hard to spell.

And the Dark Ages were never the same as the Middle Ages; the DA came before the MA. Today they're called Late Antiquity, and lots of it came before Islam existed.

Greger Olsson - 2018-04-05

Graphics Designer: "Nerds...." :-)

Michael Sommers - 2018-04-05

It depends on how you want to divide up the periods. Some people do start the Middle Ages with the fall of Rome. Others start them around the year 1000 or so. I think the latter makes more sense, since society in Late Antiquity was very different from society in 1000. Regardless, as you said, the term 'Dark Ages' is out of fashion, for good reason.

Wizbro - 2019-01-15

got a good chuckle

Discomfort - 2019-01-24

@Michael Sommers It began with the rise of monotheistic religions in Europe. But it depends on where in the world you mean. The more popular school of thought is that it began with the rise of feudalistic realms.

Jake Fields - 2020-02-26

I totally misread the title as the aughra effect. Getting ready I was, speak to the gelfings I must.