The Unruh Effect

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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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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
arxiv.org/abs/1709.02200
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[@antiisocial]

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

[@jaimemagnum]

My life in a nutshell

[@anshgawai]

@@hashtagnoname3931 that also adds to his problems

[@martingrey2231]

That will cause a problems in it's own. The least of which are sore calloused feet...you will also need random people to hand you bottled water at regular intervals. Are you sure you have thought this out???

[@christopherellis2663]

There is a big difference between Now and Probability.

[@iqinsanity]

Run Forrest Run!!!

[@takeshiC1]

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

[@Madrawn]

You can increase the frequency with which you rewatch this and your understanding would come asymptotically close.

[@arpioisme]

don't worry, that's just ignorance keeping a constant acceleration

[@kylewatson4771]

It's big word time

[@ballelort87]

Lol love these comments

[@Dziaji]

Because the video is garbage.

[@KungKras]

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

[@pressaltf4forfreevbucks179]

You sir, have earned a banana🍌

[@user-fo8lz6om7l]

Pfft! Every time I hear him say that I snicker. (I may binge watch these like clockwork)

[@marzi_kat]

A black hole? In _my_ computer...? It's more likely than you think!

[@tutonme]

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

[@readingRoom100]

lol, by that, you should get an even lower score

[@IWasAlwaysNeverAnywhere]

you both see the wrong answer. you just see the proof for why its wrong..i guess?

[@IWasAlwaysNeverAnywhere]

@Steven bent1 you see how my reply now has your name in it in this comment? you see how my name is in your comment? if i wanted to reply to you i wouldve. i didnt even read your comments but im going to now. and ill probably reply.

[@IWasAlwaysNeverAnywhere]

@Steven bent1 okay i understand now. youre completely disconnected from reality. why did you give a lesson of this stuff to tewt when he was just telling a joke? it wasnt a great joke but it definitely wasnt intended to be taken seriously or literally. what made you think it was appropriate to say all that? xD and now you cant even use enough logic to realize i wasnt talking to you. not only that but who tf says "spoofing" and "blat" tf does that even mean?

[@asahmosskmf4639]

Steven is young and cool, with his words no one uses. And... not reading that hate book of a reply...

[@mattc3738]

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

[@Radonatos]

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

[@genryheorge9614]

My new favorite quote. No srsly lol

[@megaglub6347]

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

[@barbarianjk2355]

Bruh

[@pressaltf4forfreevbucks179]

Bruh momentum

[@david94549]

The unbruh effect: In the event of 1 (un) bruh - more bruhs will follow. As evidenced above

[@YesPlease964]

@@david94549 as above so below, bruh

[@tacopacopotato6619]

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.

[@michaellepore105]

If that gets you check out quantum inertia theory!

[@randomdude9135]

@@michaellepore105 Isn't that part of Physics?

[@doremysheep7864]

Yes! Someone else gets it!

[@doremysheep7864]

@@randomdude9135 a deeper level of physics. Quantum Physics, like physics but 1000x cooler

[@paulfrancis8836]

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

[@djbslectures]

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

[@slashusr]

Hey! Save your "likes" for Matt. He's the one who said it!

[@comebacktheman]

"It's been worked out by Matt and everything" :D

[@jessstuart7495]

I want a bumper sticker that says that!

[@johnmckown1267]

Like math has never pulled a prank on me before. ;-)

[@jjsmith706]

Jess Stuart Or a tee shirt.

[@feynstein1004]

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

[@GothicGamer2012]

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]

It’s gibberish garbage.

[@elliotmcgee8918]

Sounds like someone didn't understand it

[@pressaltf4forfreevbucks179]

@@elliotmcgee8918 u think?

[@gabrieldelacruz7100]

same here

[@kattenelvis1778]

That's not due to a lack of intelligence, that 's due to a lack of education in the subject.

[@iinRez]

Slowly but surely, I am beginning to understand. Thank goodness for PBS Space time.

[@NewMessage]

The Rindler would make an amazing Batman Villain. He'd never be able to catch up with him.

[@gregerolsson1713]

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

[@wcsxwcsx]

Other way around, Greger. These are lean times for PBS.

[@michaelsommers2356]

+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.

[@gregerolsson1713]

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

[@michaelsommers2356]

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.

[@2asseddog]

got a good chuckle

[@PeterJavi]

"A space-time diagram has two axes, space and time." Thanks, I learned something new.

[@ynntari2775]

and in that phrase lies all our understanding of the video

[@funkyflames7430]

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

[@gl1500ctv]

"Display of acceleration" or "exhibition of speed" in some places. I was written specifically for NCGS § 20-154: Signals on starting, stopping or turning. (a) The driver of any vehicle upon a highway or public vehicular area before starting, stopping or turning from a direct line shall first see that such movement can be made in safety, and if any pedestrian may be affected by such movement shall give a clearly audible signal by sounding the horn, and whenever the operation of any other vehicle may be affected by such movement, shall give a signal as required in this section, plainly visible to the driver of such other vehicle, of the intention to make such movement. The driver of a vehicle shall not back the same unless such movement can be made with safety and without interfering with other traffic.

[@Mernom]

It's interesting how you can use different explenations to different events, and find out that the end result is the same. To me, it adds credibility.

[@ChaoticNeutralMatt]

Confluence

[@HoD999x]

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

[@PulseCodeMusic]

As challenging as this is, this is why I love this channel... There are tones of channels that explain medium level concepts usually atleast a bit dumbed down if not down right misleading but I want to challenge my understanding and go further, and that will always involved feeling slightly confused. Great stuff keep it up!

[@TheFLOW1978]

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

[@madnessbydesign1415]

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!

[@Bassotronics]

Madness by Design Lmao!

[@jamril1936]

You better be constantly accelerating when you get pulled over.

[@faiselbutt2944]

Yes, because we have not found any practical applications for science yet.

[@mattball420]

If you keep moving fast enough his cops lights will never catch up to you and you will never know he was pulling you over

[@madnessbydesign1415]

Thomas Bigalow, my little Honda may need some new tires if I'm going to test that idea...

[@FireHax0rd]

This is the most interesting and knowledge-filled science channel on KZbin that I know of and that doesn't dumb down concepts (as far as I can tell, anyway) -- thanks!

[@Ides385]

Amazing that you can get this quality on youtube.

[@djschultz1970]

isaac arthur's channel is better in my opinion. but spacetime is a very close #2. they are both awesome. should do a callaboration episode someday.

[@modolief]

So true!

[@NishilMistryIsolation]

If they don't dumb it down then they have no use on KZbin where layman people are trying to understand these fascinating concepts. If we are talking about intellectuality then Feynman said, "If you cannot explain the most complex concept to a layman person, then you yourself haven't understood the concept."

[@Sabercat-ub9dc]

I am not a physicist or learning to be one so I will take your word for it. Most of it is nonsense to me lol. However what little I do understand of it I find very interesting.

[@alterego3734]

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

[@mamtasahu286]

Underrated

[@siquod]

The top of a tower in a planetary gravitational field experiences less Unruh radiation than the bottom. Could this, in theory, drive a heat engine? If so, where does the energy come from? If not, what prevents it?

[@radishpineapple74]

I think that any photons originating from lower in the gravity well would be gravitationally redshifted as they go higher in the tower so that, locally, there would be no difference in temperature required for a heat engine. Just a guess though.

[@coopergates9680]

I guess if you captured the radiation you'd be draining energy from a quantum field. How other energy makes its way into that field is another matter...

[@kevinlam9785]

My guess is that from the pov of any observer on top of the tower, the bottom of the tower is more gravitationally time dilated, causing the perceived temperature of the bottom of the tower to decrease (by decreasing the perceived speeds that particles move) to the extent where there is no more perceived temperature gradient. This would mean that it would be impossible to conduct heat from the bottom to the top of the tower.

[@siquod]

@@kevinlam9785 Sounds like a good explanation.

[@greyareaRK1]

I heard a sonic boom as that passed well over my head.

[@gravijta936]

Watching the video at 0.25x speed might help ;)

[@theotheremily]

Gravijta as long as you're accelerating away from it

[@skizzydarealest]

Gravijta ha. got eeeeemm!

[@influenza99]

at one point I thought he was just making up words.

[@bradkw4295]

on the bright side, I understood so little that I didn't even have a chance to feel dumb...

[@c22madkat21]

all this stuff went over my head.....thank god it wasn't accelerating

[@Y2Kr4SHM4N]

I see what you did there!

[@Kram1032]

But if you listened to the end of the video you'd know that, yes, you actually were.

[@zh3521]

LMFAO

[@alleycatw9l]

I thought his joke wasn't observable unless you were also accelerating?

[@larryphillipsjr.1607]

Razvan Groza 😂

[@carloss.4511]

It feels incredibly refreshing to see such an original subject so well explained (given the complexity of the subject). Keep up the great work!

[@kenmunoz8517]

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!👍🏽

[@lightstudios1421]

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

[@thedeemon]

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

[@sudoscience5084]

That books been on my shelf for a longtime. Every so often, I take it down start reading, and abandon it after a few chapters of extreme confusion. The rest of the time it just sits there, mocking me

[@SBImNotWritingMyNameHere]

​@@sudoscience5084so how about now? "Yes, of course" happened a bunch of times now?

[@zapleaf]

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

[@hopydaddy]

I once majored in physics in college, and I still have trouble understanding most of it because I was never thought these things 40 years ago back in college.

[@evee2727]

watched all you vids and have to say i wish you were my teacher as a kid. you amazing as a teacher ... very easy to understand your words and even tho im still learning the info rewatching it is never boring..... i bow down to the master of space time

[@alexkorocencev7689]

The Bremsstrahlung Radiation created close to a Schwarzschild Radius of a Kugelblitz might create the Zitterbewegung Effect. There are a lot of German words in the theory of Relativity.

[@Rhekon]

Alex Korocencev it's relatively German

[@thstroyur]

'Bewegung'

[@alexkorocencev7689]

Iago Silva Right, I'll correct it

[@RoySchl]

And then it all ends in a "Kraut und Schnitzel Explosion"

[@alexkorocencev7689]

weak hyper charge Such expressions are more common than they should. Like DC Comics (Detective Comics), HIV Virus... Cool name by the way :3

[@tomkop213]

Even if I don't understand half of this is still refreshing to watch and learn something giving all the flat earth channels that keep popping like mushrooms. Keep it up Matt.

[@shirleymason7697]

Ace Rimmer .......I agree. I’ve watched many dozen that seemed to be grade school level. Another problem for me is too frequently beginning back with Copernicus, or Newton. Takes too long to get to the meat. I rarely understand much of this, but I want my mind to be pushed.

[@stesar2700]

Thank you Matt, i learned a lot from your videos, this one in particular gave me a bit of confidence and momentum on the serenissima project for a new interpretation on QM. One of the best channel of modern physics.

[@boriscrisp518]

fantastic video, this is the sort of mind boggling thing we would never get on tv back in the day

[@rud]

I feel a bit unruhe by knowing that.

[@ozdergekko]

jo, i aa. rastlos unruhig.

[@Or2DanceFloor]

the names of some of these phenomenas, even if they are from scientists sometimes fit very well. Unruh radiation like the restlesness of an accellerating observer or the blackness of a black hole with its Schwarzschild radius.

[@ozdergekko]

Schwarzschild wasn't even an Austrian ;-) [note: sg. phenomenon, pl. phenomena]

[@Or2DanceFloor]

Austrian, german or not, these german names have an uncanny connection with their findings. Well sorry for making these grammar mistakes as a non native english speaker.

[@ozdergekko]

Np, most Americans use it completely wrong too. It's greek, that's why... Nah, I'm Austrian, so it was kind of patriotism why I wrote that. Yeah, you're right. Schrödinger, Unruh, Schwarzschild, Mach, Boltzmann... But why uncanny? They were not Nazis.

[@Schenkel101]

Me: K Matt, an intellectual: °K

[@KrisBogdanov]

but Kelvin isn't written with a degree sign :D

[@Schenkel101]

Kristiyan Bogdanov welcome to the joke.

[@Rael14]

YOU ARE WELCOME

[@rydohg]

Kelvin is an absolute unit so there isn't a degree sign

[@michaelsommers2356]

He and the people he usually talks with are smart enough not to care about such trivialities.

[@PanchoKnivesForever]

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

[@krzysztofs3t532]

I still belive that this is one of the best and most interesting episode in the whole series... and maby this one about information limit of the universe :) Good job!

[@tanithrosenbaum]

4:30 Except if they managed to drain all the energy in the universe, they'd also have drained the energy of the photons that make up the message. And so the message won't catch up with them after all... :)

[@Leo-hk6qg]

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

[@Tadesan]

I love how coherent all these concepts are!!!

[@Lectrue]

Excellent video! Thanks for breaking down the concept of Unruh radiation!

[@mindcozy4125]

Does this mean that one could develop a truly universal accelerometer by measuring Unruh radiation?

[@YodaWhat]

That is a deceptively deep question. Remember: All acceleration is relative.

[@DKOILive]

@@YodaWhat speed is relative, but acceleration is absolute.

[@YodaWhat]

@@DKOILive- We feel weight because we are accelerating towards the Earth, usually at zero speed. At the same time we have accelerations we do not feel despite the considerable speeds, for example around the Sun, and also the Moon accelerating around us. Then our entire Solar System is accelerating around the galactic center and the whole galaxy is accelerating towards the Andromeda galaxy. These are just a few of the countless examples of relative acceleration. Finally we come to an example that might be in keeping with your claim: If you were in a space ship that was alone in the universe and you activated the engines, you would feel acceleration as usual, but you would not be accelerating towards anything, since there would be no other thing. In that case, your speed would also be unreferenced, and therefore neither is relative. So your claim does not hold up to scrutiny.

[@DKOILive]

@@YodaWhat The centripetal acceleration at the equator due to earth rotation is 0.03m/s^2 you don't feel it not because it is relative, but because it is negligible, however measurable. Centripetal acceleration of earth towards sun is an order of magnitude less ,0.0059, and if we are talking of sun accelerating in its orbit around the galaxy centre, it is on the order ten to the power of minus ten m/s^2, thus, miniscule and impossible to feel, despite being absolute

[@musing1977]

It would appear, there would be no way to determine if the radiation you are detecting is Hawking radiation (as near black hole) or Unruh radiation (as if you are accelerating), if you were in a box and unable to figure out what is going on outside. So this way Einstein’s equivalence principle is protected.

[@sebastianelytron8450]

How about teaching us about the *Ruh Effect* first and _then_ teaching us about its inverse!

[@garethdean6382]

Everyone knows the Ruh effect. Sit around all day and you'll look cool.

[@aryamanmishra154]

trynna be cool? You failed

[@Phobos_Anomaly]

@@aryamanmishra154 Ironically, so did you.

[@anmaister]

Its been a few months since this channel popped on my suggestions, I realized in the first 5 seconds how I didn't miss *Matt's "Whistling"* .... Excellent show btw...

[@nickcooper1568]

Been watching for years but this video really takes the cake! Bravo for making physics approachable at an intuitive level, maybe some day we'll even use maths

[@xaknitram]

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

[@TheMrhockey32]

IM HERE BEFORE THE BLACK HOLES CONSUME US ALL

[@SuviTuuliAllan]

consumerism gone wild

[@vgerlightning7134]

I've digested enough for a day, thanks, cool Matt.

[@RedLeader327]

This channel blows my mind in so many ways.

[@mheermance]

Since the existence of particles is observer dependent, and everything is made of particles. Is it possible for two observers in different frames of reference to disagree on the existing of macroscopic objects?

[@TheMrMxyspptlk]

I think this is the most relevant question after the video. I don't understand why people are not just keeping asking that

[@RadixSortable]

Seems unlikely for the reasons quantum jitters and other quantum effects are not visible on macro objects. However if the universe as a whole is accelerating does this mean that particles are created and can interact to form the molecules and macro objects of our universe?

[@admiralhyperspace0015]

RadixSortable Well can universe move.relative to What.even if it accelerates in the multiverse.the unruh stuff he is talking about is the consequence of our universe laws not multiverse laws.But if all of this checks out.then our whole universe is an observer acelerating in the multiverse and creating us and everything we know as unruh radiation.WOW.

[@sMASHsound]

so, the observer accelerating away from the particle, so that it effectively doesnt exist, and for the observer accerating in such a manner that they can observe the particle, they be existing in different sides of the horizon, and there fore not be able to interact, ever. their observations would differ, if they could be compared, but will never exist in the same reality to be compared. for one to see the particle, them and that particle must be in the same side of that horizon. and for the other observer to NOT see the particle, they must be on the other side of the horizon. effectively, the obsever who can see the particle doesnt exist to the observer not seeing the particle. think about it in terms of the sound barrier. if a fighter jet is going faster than the speed of sound, and that jet fighter is our observer. then we have missile launched at him at less than the speed of sound. it makes a noise, but because the jet fighter is faster than the speed of sound the missile's rumble never reaches him so he never hears a missile coming. another guy who is travelling towards the missile with his own jet, will enounter the sound waves, and can hear a missile. he over takes the missile, but still is going at a speed slower than the speed of sound, so he still hears the missile, although the waves are really stretched out. but, because he is still slower than the speed of sound, he is still on the side of the horizon that can observe the missile. and does not exist, audibly, to the faster jet fighter. andddd, because no sound can go faster than speed of sound, and no thing can go faster than the speed of light, unless the faster jet fighter changes acceleration to another direction, turns around, they will never exist to him, as nothing from their side of the horizon can cross forward.

[@slashusr]

and best of all we can ignore grammar spelling and punctuation wOw

[@yerbamatey918]

i thought the thumbnail said the “bruh effect”

[@madzombie]

Same

[@yin-chengkrishuang8405]

I'm glad to see a pop science video describing Unruh radiation at last. Thanks!

[@matthewlind3102]

Thank you so much for this video

[@Islandsunn]

isn't this used as the basis for "quantized inertia", that the energy produced by unruh radiation acts as inertia for very fast moving objects like spinning galaxies?

[@Doping1234]

Bei mir verursacht der Effekt...Unruh' *ba dum tsss*

[@V0TION]

Hallo

[@TheJohnblyth]

Wonderful! And throw frame-dragging into the mix :)

[@matthewmarkham4195]

I usually understand spacetime videos because Matt and the team do such a good job. This one however went way over my head.

[@rapur7929]

That moment, when you're early on a Space Time video, but have nothing smart to say.

[@brendarua01]

That moment when you realize you're talking like a commercial... lol

[@fParad0x_]

That moment you're just wandering around the comments section

[@alexkorocencev7689]

That moment when you really want to be mentioned in the next video

[@fffUUUUUU]

Péter Tóth so keep your mouth shut dork

[@Rose_Harmonic]

You just need to find your idea elsewhere... in space-time.

[@jokiboy9153]

This video left me more stupid.

[@SuviTuuliAllan]

*right

[@scalp340]

Yup! Came here to say this. I watched it twice and I still don't understand.

[@LuisAldamiz]

Something about ligh cones. What is beyond the light cone will never reach you and when you accelerate (begin moving, stop moving, change speed of movement) you displace your light cone in space-time and that such a change causes a minor event horizon. So far so good. The complex part is the particle detector thing but just take it at face value because brilliant minds have made the calculations for you.

[@massimookissed1023]

That feeling when you weren't confused at all, and then there's a new vid from PBS SpaceTime.

[@slashusr]

Tolyngee Absolutely the best comment ever. Mind if I copy and then paste indiscriminately?

[@greypaladin4560]

Sorry I'm late to watch this video. I was accelerating pretty hard and forgot to stop to check for YT notifications. Plus I was halfway to Pluto, so that took some time. Great Video.

[@OldKingSol]

Oh, how cute. The tiny "you" on the world line is animated, too! I dunno' why, that just seems totz adorbs. ;-) Interesting subject, for once this is something I _hadn't_ heard of before. Merci! :-)

[@johnsonandjohnson10]

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

[@nischaldhungana7014]

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

[@drewschmaltz8950]

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

[@jackmack1061]

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

[@glarynth]

Last time I was this early, I was in a warm bath of particles.

[@brendarua01]

Bubbles!

[@davidinmossy]

I prefer a blistering shower of plasma.

[@jsupattanakitti]

Warm's an understatement friend.

[@ariochiv]

But not very warm.

[@808bigisland]

Wonderful. Thanks!

[@NomenNominandum]

These animations are awesome !

[@AvyScottandFlower]

At first I thought the character in the red suit was Stephen Hawking.. Yes, I'm going to hell

[@Mafila]

When I first glanced at the notificiation for this, I thought it said "The Untruth Effect".

[@garethdean6382]

It DOES say that. It says that now, pinkie swear.

[@aaronsmith6632]

Great video, thank a lot!

[@YellowPenetrator]

Every Time I Click one of your Videos is like a coffee to me because it’s so much more Louder than other vids

[@whimpypatrol5503]

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

[@bbgirish2935]

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

[@vebbto]

Although this description is not precise, I find that this video is a helpful additional explanation as I'm learning about this (as a master's student of theoretical physics).

[@kerschplatt]

I for one have always loved the Bogga youbov transformations. Especially on Halloween.

[@GregoryCunningham]

One of the better X-Files episodes. 😁

[@koreyjeffers6963]

0:38 Matt is killin it in those new sneaks

[@MsSomeonenew]

I'm glad you concentrated on the important parts...

[@2asseddog]

You mean the cardboard box is relating to you specifically

[@7thquark309]

That's really mind-blowing ! I would have never imagined that you were friend with a space monkey.

[@recklessroges]

I'm used to not being able to fully keep up, but this episode went full turboencabulator for me. (The first time I'm going to have to watch more than once to convincingly nod knowingly at a Space Time video.)

[@pressaltf4forfreevbucks179]

Me when i realised this episode had diagrams: bruh effect

[@KrisCadwell]

When you say the existence of particles is observer dependent, do you mean in general or only in this specific situation?

[@thedeemon]

In general. The very definition of a particle in QFT is tied to time axis, basically, so different observers with time coordinate pointing differently have different notions of particles. In case of just constant speed difference, the difference in particles is just a change of frequencies, i.e. momenta, numbers of particles don't change. But for accelerating observers things get more interesting, even number of particles is seen differently.

[@RichardASalisbury1]

Wow! You the best 'splainer I know of this stuff. More!

[@feynstein1004]

SciShow Space did a video yesterday about Blitzars, which are super awesome. PBS Space Time should do one, too.

[@BatJeff]

I was having such a "meh" day then I saw a new Space Time video was uploaded. Thank you PBS Space Time for making my day a little bit more bearable.

[@Scribe13013]

That t-shirt is actually a tattoo

[@radar9561]

This is the first episode that had my head spinning and I've seen them all

[@PotatoSmasher420]

The Rindler horizon part of the video with your photon and "friend" reminded me of the Achilles and tortoise paradox.

[@johnw393]

Everytime I see a dislike on a science video I can't help but wonder if they just don't understand or if they are a flat earther?

[@jrbrodiejrbrodie4568]

could also be an educated person who had some small gripe about some claim that was made.

[@brendarua01]

I've wondered about that too. At first I thought it was related to production or presentation. But one even sees it on very well done presentations. I think many are just trolling or have a need to hate.

[@Lucroq]

Are you seriously suggesting every single flat earther is a troll or are you the one who's trolling?

[@Ennar]

tbird81, that would be on the same level of conspiracy as faking the Moon landing.

[@parzh]

Isn't it the same really?

[@gagago302]

Is "Horizon Radiation" synonymous with "Hawking Radiation". Just wondering due to it's mention at around 1:00 because it's paired up with the Hawking Radiation video. I'm not savvy on the quantum physics jargons so I was thinking that it was likely just a a Freudian slip but wanted to verify that it's not synonymous quantum lingo that I'm not privy to.

[@oxcy993]

There are other radiations at/below the event horizon but seen as he referred to his video on Hawking radiation when he stated 'horizon radiation' , in this case, it was synonymous with Hawking radiation. It wouldn't always be synonymous but Matt wasn't incorrect to say it in the context he did

[@gagago302]

Oxcy - I think I get it; thanks for the info

[@joemasters2270]

Excellent episode.

[@FlyingJetpack1]

This video left me with a few questions: 1) In the hadron collider we accelerate protons almost to the speed of light. Would the Unruh effect have any noticeable effects on the condition of said protons? 2) If a non accelerating observer cannot see this Unruh radiation coming from the particle that is accelerating at the speed of light, if we were to choose an atom that coincidentally can get his electrons excited to a higher energy level by absorbing said radiation for his acceleration, and put it in the hadron collider. Will we see that atom spewing out those radiation particles and slowing down in the process once he hits that specific acceleration?

[@DonSolaris]

Hey Matt, what would happen if nothing would happen?

[@sebastianelytron8450]

kzbin.info/www/bejne/qaGaaoRuiMisn5o

[@Murkinos]

Don Solaris nothing

[@odinakazeus]

Don Solaris the same that happens when you devide by zero

[@kingfisher1638]

@dead abyss so it blows up to infinity?

[@khalilrahme5227]

Don Solaris nothing can't happen,go read about entropy ;)

[@singingtallit583]

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

[@judahrosen4362]

that would mean you could out run causality

[@armangaloyan5826]

@@judahrosen4362 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

[@I_dont_need_a_handle]

Ironically enough, "Unruh' " or "Unruhe" is the german word for restlessness. So if you were to use the german pronounciation for Unruh-radiation (Unruh-Strahlung) in front of german students, some would assume it is the inherent description of the type of radiation much like with Bremstrahlung (braking-radiation) or Hohlraumstrahlung (cavity-radiation).

[@richardaversa7128]

After all these videos I still never see the "...in spacetime" homage coming. Dude is a master

[@TheExoplanetsChannel]

*would love to see a photo of a black hole, hopefully soon..*

[@bautibunge737]

The Exoplanets Channel you would probably just see Einstein rings

[@sebastianelytron8450]

*would love to know why people bold their comments, hopefully there's a point to it..*

[@pistolpackinmama8295]

Follow the EHT - Event Horizon Telescope. theyre currently taking and rendering shots of the black hole in the middle of the galaxy!

[@beardedroofer]

Black holes are not what we have been led to believe.

[@bobleb3284]

With a long enough exposure time, and a camera that can detect hawking radiation, it should be possible to image a black hole. (this would probably take more than trillions of years of exposure time)

[@firexgodx980]

How does the unruh effect interact with the accelerating expansion of the universe

[@fugslayernominee1397]

Yeah i wanna know that too😐

[@mathieuaurousseau100]

Probably not at all, the expansion of the universe makes object farther from each others without giving them any speed and the "accelerating" in accelerating expansion just means that effect gets stronger and stronger, it's not an actual acceleration

[@adlex1212]

The universe itself doesn't accelerate, its expansion does, or so it goes.

[@Johncornwell103]

Well matter itself isn't accelerating but space is. I mean draw two dots on a deflated balloon and then fill it with air. The dots will be accelerating away from each other even though they actually haven't moved. So expansion probably doesn't do anything then again IANAP

[@WillToWinvlog]

Great vid!

[@tomscisci7331]

You were on the screen two times! And it looks cool.