The Strange Universe of Gravitational Lensing

Is what we see in the night sky a true representation of our universe? Find out about Gravitational Lensing in this episode and even more about it in the documentary that Matt made together with the Museum of Natural History:Distant Quasars: Shedding Light on Black Holes www.amnh.org/explore/science-b...
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Niels Bohr, a Danish Physicist said “Everything we call real is made of things that cannot be regarded .” Is what we see perceived to be real or is it an illusion?
In the world of our mind’s eye, light travels in a straight line. In reality, spacetime is deflected and magnified through the lens of gravity. Find out how this works and what it allows us to learn about our universe in this episode of Space Time.
Written and hosted by Matt O’Dowd
Made by Kornhaber Brown (www.kornhaberbrown.com)
Comments by:
AyyElMao
• Is Quantum Tunneling F...
Błażej Michalik
• Is Quantum Tunneling F...
Flynn Kruchell
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Mystyc Cheez
• Is Quantum Tunneling F...

[@BunnyOfThunder]

It's cool that between this video being made and me watching it today, the light around a black hole has been observed.

[@pierfrancescopeperoni]

@Gabe Mendoza Same also for me: maybe we three are in the same universe.

[@zacharyadams3772]

@@pierfrancescopeperoni seems implausible.

[@Diogie12]

Matt is like a new Doctor. At first I resisted because he was different and I liked Gabe, but after getting used to him I never want him to leave

[@SuperPhunThyme9]

Matt needs you to cough twice now

[@EvanFromJersey]

I began watching Matt so our situations are seemingly mirrored

[@whatthefunction9140]

Space Time And Chill

[@TheVideoChain]

LMFAO. ...I would MARRY her ASS

[@whatthefunction9140]

How do you think I met my wife!

[@TheVideoChain]

+Dylan T LMFAO. .. AWESOME! ..... that's where I went wrong in life .. because my work inflicts this life if solitude. .. my lady nor my friends want to hear anything that consists of the prefix "astro"....

[@brandonhall6084]

Space Time and Heat Death*

[@melparadise7378]

I'd buy that shirt

[@Darxide23]

How did I not find this channel until today? This is the stuff I truly wish I knew about when I was younger and had gone to school for instead of what I actually went for. Astrophysics, Cosmology, Quantum Mechanics. I love it all.

[@alextaramas7872]

It is my personal opinion that your videos are awesome . The work you put in making them is truly appreciated by me and many other people. Good job for making your videos the thing i look forward to the most and for teaching me all those great things and giving me motivation to learn more and educate myself more .

[@ChrizoPrime]

This gentleman is brilliant, and so is his beard.

[@1112viggo]

yeah the Leonidas beard works well with the Jesus haircut^^

[@scottwest5704]

He lost me at curving time, just too far fetched

[@dm3892]

Geh

[@user-nw6oj4wb2k]

I am so grateful you provide in depth and accessible insight on such amazing science. Its hard to find such an accessible and thorough source

[@jamboni]

Finally watched all episodes - love this channel! It hurts my brain so I know it's good!

[@vorea]

Does anyone else love the background music of these videos?

[@n4thanfv]

thanks for another video. space-time is the best channel in youtube! i can't wait for the next episode!

[@shilpashivadasan5115]

Pink Freud i like ur punny name

[@keronplug14]

Oh god! Thankyou for putting subtitles in your recent videos now! You don't have any idea how long do i wait for it.

[@linux-xe2b366]

Kudos for great video and awesome clear explanations! I'm always waiting for the next one.

[@aliciabaumgartner1406]

Can you do a vid about the negative heat capacity of black holes? The fact that black holes decrease in temperature as their internal energy increases is quite bizarre.

[@scottwest5704]

How can Time be cjrved?!!!?

[@Minptahhathor]

@Scott West it doesn't curve time, it curves space and slows or speeds up time, since time and space are kinda inseperable up until a black hole,

[@SciencephiletheAI]

Good video, mortals.

[@shyamdasd6963]

Sciencephile the AI where are you, waiting for your precence

[@cowthedestroyer]

come back pls

[@sean640]

oui 🥲

[@lewismcdonald3090]

Wow this is the biggest anime crossover even ever seen !😂😂

[@manusartifex3185]

Don’t distract me I’m watching this

[@duncanw9901]

I love this channel SOOOO Much. I love QM and can't wait for a more detailed description

[@ViciousCrabz]

Love the show man I gotta watch you a few times but you do a great job of explain explaining the complicated stuff. Still wish I understood all of it but you've taught me a tonne. Keep it coming.

[@whatthefunction9140]

Yeah the use of the word "observation/observer" when talking about qm systems needs to die. So many people think this means a person needs to look at it. as if the quantum world cares about our consciousness.

[@happytriangleman1157]

I don't really understand it in this case, but i know exactly how you feel! (looking at you the use of word "science")

[@iamjimgroth]

I often have to describe observing as "being effected by".

[@dermusikman]

Can you share resources on this? I've only found assertions either way.

[@PhillipCarterPearson]

I've always been troubled by that conclusion because that's what I had thought. Please elaborate

[@whatthefunction9140]

let's say there is an electron moving through a vacuum. It could be a particle or a wave. Often physicists say "but we don't know which until someone observes it. then it chooses to be a particle or a wave". This completely anthropomorphizes the electron. It has nothing to do with someone observing it. it has to do with that electron interacting with other matter/energy that determines its state. that could be it hitting a wall. flowing through a wire. jumping from one atom to another. hitting a scientists measuring device. etc.

[@AveryMcChessney]

I love this show, It's kept me going through life week by week just yearning to learn the next big thing. My world view has changed so much for the better because of you guys at PBS, as has my character and outlook on life. Despite the occasional existential crisis of course ;)

[@raiinydaze5893]

Such a fascinating and well-explained video! I'm using this for my science olympiad sessions, thanks for posting this

[@mrautistic2580]

really cool to hear you talk about the particular subject you're involved in

[@haydenhouse5472]

I have some questions on light traveling through space/time. If a star is shining, first is it just a constant stream of photons in every direction? One photon after another with no space in-between each photon? If so or how ever it exactly works, have we ever seen the "first photon" from any star traveling through space/time? Also then if you go to the farthest star towards the "edge" of the universe and the "first" photon traveling at the speed of light is it then expanding the universe? Space/time is coming into existence as this "first" photon gets to it. I had this theory when I was a freshman in high school many years ago and I have yet to hear anything on it. I also have another question pertaining to this video. If a star is behind a black hole say ten light years behind it. Then the photons are coming straight at it.Ten years later Do the photons go straight into the blackhole? So if we were in front of the blackhole we would not see that star? Also like the "monkey and unicorn" on your old video on blackholes would the "constant stream" of photons to the observer just be smeared on the event horizon? Even though they are traveling at the speed of light into the blackhole to the observer we can never see anything actually fall into the black hole because the time dilation? I also am pretty sure I have figured out why Einstein could not figure out the "theory of everything" and am pretty sure I figured it out, I just don't know how to make a cool little video to show everyone... I would also LOVE for you guys to make a video on the "Double slit" experiment! That changed my LIFE!!!!! You guys are awesome and people if you haven't checked out the documentary Matt did with the Museum of Natural history in the description you need to! It is AWESOME!!!

[@DarkOps2442]

incredible questions! PLEASE ANSWER MATT!!!

[@haydenhouse5472]

Thank You Leonardo! I really hope he does answer!

[@DarkOps2442]

People need to like it to the top so he reads them!

[@haydenhouse5472]

btw I get at the very end of this video you kind of explained my last question but I still am a little confused about the description.

[@argh523]

"The first photon" is a very hypothetical thing. The fusion in the stars core is what releases photons, but these packets of energy don't get very far. It takes thousands of years for the energy to "travel" to the stars surface. When a star first ignites, it is still surrounded by a cloud of dust and gas. The light then starts to blow all that away. So the first photon you could ever see from far away really isn't the first that the star produced/emitted anyway. And even if you capture the first photon emitted of anything, you wouldn't know. All you know it it's the first that you detected. And a single photon does not a picture make. A similar thing (similar to stars beeing shrouded in dust that needs to be blown away before they become visible from far away) happend in the early universe. In the soup of fundamental particles the photons would be absorbed and re-emitted after very short distances, making the universe opaque. Eventually things cooled down and thinned out enough for electrons and protons to combine into neutral hydrogen. Afterwards, it became possible for photons to travel much longer distances without beeing absorbed. For example, 13 billion light years, until beeing absorbed in a radio telescope on Earth. This is the "first light" of the universe, the oldest light we can see anyway, and it's called the cosmic microwave background, and the event, the moment it was released, is called the recombination. As for the star behind the black hole, yes, the light that would shine directly at the black hole would simply be absorbed, _however_, the light that passes the black hole closeby would be bent. We could still see the star, but it's not a direct line of sight, so we would see it in a slightly other position than it would be if the black hole wasn't there. The image might be distorted in a buch of weird ways too. This is what this episode of Space Time you presumably watched was all about. The entire episode is about this Gravitational Lensing of light. > I also am pretty sure I have figured out why Einstein could not figure out the "theory of everything" and am pretty sure I figured it out I'm not a physicist, but I'm gonna boldly predict that no, you haven't ;)

[@YYYValentine]

Hi! What causes the Einstein Cross's cross shape? Why it is not a ring, or a random like image?

[@AJarOfYams]

^ this

[@brasildocara]

Mr Felatio could you show your math supporting your point?

[@moxshyfter]

Think of it this way: you're asking why an intense beam of light (which is pretty narrow) isn't forming a perfect circle as it's blasting by stars and galaxies that don't even remotely resemble the circular shape of the beam. Shine a flashlight through a tangled fishnet, and that'll be a rough equivalent to what's happening to the light of the quasar.

[@RichieHendrixx]

5:37 it is random

[@pbsspacetime]

+MrFatilo Great answer. Do you even lens? To restate some of this with some ELI5(10?) language: If your light source, lens, and telescope are _perfectly_ lined up on the same axis, and your lens is perfectly circular around the line connecting the three (the optical axis) then you'll see an Einstein ring. How perfect do they have to be lined up? It depends on the size of the light source. If the light source is large - e.g. an entire galaxy - then its easier for some of the galaxy to be on the optical axis and then you'll see a ring. But the light from quasars comes from a very, very small region (1 light day vs 100k light years for the a galaxy) and so we never, ever see an alignment so good that the quasar is on that axis. We DO sometimes see the Einstein ring from the galaxy that the quasar is inside. A nice example of this is one of the (very few) other cross-shaped lenses, HE0435-1223. Check it out: bit.ly/28HxuXh The quasar still appears as four points of light, but in the infrared image ('H') you can see the Einstein ring of the quasar host galaxy.

[@Tadesan]

Wow dude. The thought process at 3:50 is great and is described incredibly well. Bravo!

[@Nik-vc7ox]

I watched your mini documentary. very cool. thank you for sharing with us.

[@BrunoJMR]

why does the quasar appear in 4 images when lensed an not another arbitrary number, since its light is being bent in all directions around the spiral galaxy in the middle

[@garethdean6382]

It doesn't have to be four. basically the galaxy bends the light into an 'Einstein ring' that we can't see, it misses us. (Sometimes it doesn't miss us and we see the quasar as a bright ring around the galaxy, but this is rare.) *Other* massive objects between us and the ring bend the ring's light, parts of it at any rate making it hit us. Four objects give us four images, roughly speaking. If you look at the graphic that displays when he talks about such crosses you can see some real-world examples, many of which are not 4 neat images but more unusual and smudgy.

[@BrunoJMR]

Gareth Dean so those 4 focused images of the quasar occur because light is being bent by four massive objects in addition to the spiral galaxy?

[@garethdean6382]

BrunoJMR Actually I should have worded that better, need to keep my eye on the ball. hat I should have said was that that particular galaxy has four 'lumps' in it, probably its spiral arms. These bend light more while the rest of the galaxy bends it less. The exact pattern you see tells you how the lens objects mass is clumped together. In this case in four big lumps, more or less. Hope that wasn't too misleading.

[@BrunoJMR]

Gareth Dean yeah, that's what i was figuring. so the lumps are focusing the image from the quasar by bending its path in those locations, why dont we see a ring in the middle because of the galactic center?

[@Mernom]

BrunoJMR I'd say that the arms bend it more, which causes the light to miss us. The bending from the center creates the cross. Although keeping in mind that dark matter does most of the heavy lifting in that subject is probably important. But yeah, imperfect symmetry in the shape of the lensing galaxy (whenever it's the visible or the dark matter) is the key.

[@ginzburgnathan]

fucking Einstein, how can someone be that brilliant.

[@garethdean6382]

Remember now, he didn't just make this stuff up, it's built on earlier discoveries. And sometimes someone comes along at just the right time to figure out a whole chunk of something at once.

[@Sam_on_YouTube]

+Gareth Dean That's true, but compare him to the other geniuses of his era. Einstein was far ahead of any of THEM. Was he smarter than Maxwell? Maybe, or maybe that was a product of the time. Maxwell figured out that the speed of light is constant in some sense but without Michelson and Morley he couldn't see how that was absolute. But he was smarter than people like Lorentz and Mach who had the insights that inspired Einstein but never understood their implications. While it is hard to compare people of different eras, every one in a while someone like Einstein or Newton come along that are so far above their brilliant contemporaries that they belong in a special class by themselves.

Balls.

[@arthurdotson9579]

Einstein, Hawking, etc. Science progresses steadily, then a person comes along and leapfrogs it forward, their knowledge and discoveries advancing the world as a whole (eventually...). Imagine if such potential, such brain power, could be understood, harnessed, and given to everyone.... ....and be wasted on more brainy versions of video games, pick-up lines, pyramid schemes, or the current US POTUS election fiasco. No, no, something like that has to be so rare to fully be appreciated.

[@garethdean6382]

Arthur Dotson On the other hand the slow progress should not be sneezed at. It's the small people living inglamorous lives, increasing our knowledge bit-by-bit that have given us most of the progress we see. The geniuses leap forward, but it is the rest that give them a place to leap *from.*

[@willypataponk]

thank you again for these amazing videos!

[@alivateRocket]

That's great you clarified conscious observation. Too often that is how it's explained, or how I understand it to be explained. I look forward to the future episode(s) where you go into this in more detail.

[@Perun42]

Hi, guys! Thanks for yours videos. I have a question: Why Einstein cross have as result four images of quasar instead of one curved ring of light?

[@kevinmay7935]

Basically because it’s not an actual lens. It’s not being viewed through a highly calibrated and polished material. It’s being warped and deformed by gravity itself, space itself isn’t ‘perfectly’ flat either so variation in those deformations should be expected. Also most lensing events are, yes, a ring. It takes some impressive math to separate the images an reform them.

[@Perun42]

@@kevinmay7935 thank you Kevin

[@kadourimdou43]

More Gravity waves detected, what happens when gravity waves travel through a highly curved space,do they follow the curve like light?

[@iamjimgroth]

Ooh. Excellent question. I also want to know now. :)

[@wstockall]

I thought gravity WAS the curve.

[@madmatthew1]

Yeah gravity curves spacetime, this is the theory behind general relativity, so yes light will follow the curve

[@jolulipa]

The gravitational wave IS the curve. If the waves aligned they are increased. if they interfere each other, then canceled. I think.

[@iBooa123]

So you're suggesting they travel in a 3D euclidean fashion? I would assume they would lens like light, since the oscillations are much smaller than large-scale curvature like discussed in the video. Though I have no idea if that is correct.

[@Willskull]

Amazing episode!! I always enjoy when he finishes by saying " ...spacetime"

[@keenanasbridge6911]

This videos are brilliant and very informational. Im not a scientist and im terrible at math but i love contemplating these concepts. Thank you!

[@Neceros]

Space is light soup.

[@nal8503]

I'd like some dark with my light soup please.

[@arthurdotson9579]

How much of the universe tastes just like chicken???

[@nal8503]

Arthur Dotson All of it. Everything tastes like chicken. The chicken came first.

[@veezee9256]

Chickens evolved from reptiles, they evolved from fish, which evolved from sea larvae. The egg came first.

[@roarimatrex]

somebody show this to gravity deniers/flatearthers . Einstein FTW

[@gfrozin]

Once again thank you for the awesome video!

[@jackpullen3820]

I got to say you guys really do have great questions and I have some theories I sometimes bounce over the pond and get responses to.I have been busy lately but will spend time working on these, I can hardly wait for this new book on quantum foam spin and others, ones still being translated to English and wont be ready for another 80 days.Always learning...

[@fastbuckwu]

Who else came here after the first JWST image?

[@johnharvey5412]

Stars mostly come out at night... mostly.

[@arthurdotson9579]

Hahahahahahahahahaha!!!!!

[@donperegrine922]

And the one's that don't you can't see without looking directly at it. Perhaps even with binoculars

[@arthurdotson9579]

***** He's not dumb (proper grammar, don't forget the "B" in "DUMB"), it's a play on a line from a famous scifi movie, dumby.

[@juniorcyans2988]

I'm going to take modern physics class this coming semester. I was confused by gravitational lensing and then found your channel! Space time is an amazing thing that I really want to know more! I started to be amazed or shocked by the unknown universe when I was about 11. Now I'm a physics student. Every time when I learn something about the universe, life suddenly becomes so brilliant and meaningful! Please update often! Love you!

[@Lazarosaliths]

nice video, really like how you changed the music! your mini documentary is also very cool!

[@oquera]

Is it possible that our universe is inside the smallest object in another universe? And that universe is inside the smallest object in another universe... ?

[@OdysseyMosaic]

Ahhhh...Russian doll universes...:-)

[@oquera]

And maybe when you die you just level up.

[@OdysseyMosaic]

Quite possible! Oh the endless mysteries..intellectual 'catnip'! :-)

[@DavionSobek]

I have been thinking, what if our universe is inside of a Black-Hole and that there is no expansion of the universe. The evaporation of the the Black-Hole is why things disappear beyond the edge of the universe, it is shrinking and what is already inside expands to preserve the volume of something already infinitely small! What if dark matter was simply a pattern of tidal forces that govern the laws of our universe. Granted, I have absolutely no evidence but it is hella fun to think about.

[@oquera]

Ultra Indigo Thats really interesting. I've been thinking of something similar but not to that extent. I really hope we find out some day.

[@ewanhassall7350]

what do we want? ---- STING THEORY when do we want it ---- NOW!

[@HaqqAttak]

Wasn't that mostly a dead end?

[@AMW1able]

The math works. It's one of the few theories able to combine to General Relativity and Quantum Mechanics. But it's purely theoretical. Until we can either expand an Atom to a large size (which is impossible to do without devastating consequence) or can miniaturize ourselves down to that scale, we'll never be able to actually test it. But that doesn't mean it's a dead end. When QM was proposed in the 1920's, it was viewed as a ridiculous notion, and a dead end. Now it's part of mainstream physics. String Theory just needs time and some ingenuity to become testable

[@otakuribo]

I have a theory about stings. They hurt. 🐝🐝🐝 😨

[@-_Nuke_-]

"Wasn't that mostly a dead end?" hahahahaaa

[@jonshonjohn4756]

sting theory? don't you mean string theory?

[@JustKyzuuh]

I was in New York for the first time a couple of weeks ago and watched the video in the Museum of Natural History. I was like, Hey it's PBS Spacetime guy!

[@nihil1]

So you work with Lensing too, how cool! I work with cluster astrophysics and cosmology using weak lensing to calibrate cluster masses. Awesome video, as usual. I like how careful the explanations are, both precise and accessible: combining both requires a much deeper understanding of physics than research, I think.

[@UnknownXV]

Maybe I am missing something, but if the possible locations of any given particle never reaches 0% as it extends further and further out, and yet it isn't possible to tunnel to these more extreme distant locations because they'd be in higher energy states, then isn't the probability indeed 0% at some point? Since it would be physically impossible for a particle to tunnel there.

[@ErgoCogita]

I was wondering the same thing just last week.

[@bleerrgghhhh]

I think you need quantum field theory to explain that. I imagine each particle is an oscillations in a 'web' which makes up the field for that particle along perpendicularly existing strands. But the field in which any particle's oscillation happens is contiguous, so the particles existence as a tiny cosmic vibration occurs in a similarly contiguous fashion. So, because the field exists everywhere, there's a probability of that particles' existence anywhere in the 'web'.

[@Sam_on_YouTube]

+bleerrgghhhh This is why I wish I had gotten a chance to study QFT in college. Fascinating subject. I got through Quantum II and the math just got beyond me. I hate to say, I have the same question and after reading your answer... I still have the same question unfortunately.

[@Prometheus2508]

Good question. Perhaps one must look at the quantum mechanical system of all particles a given particle may interact with. If an atom can't move to a higher gravitational energy state away from a sample of atoms, perhaps it may have a inconceivably small but non-zero probability to exist within that higher energy state because each atom could quantum tunnel simultaneously (assuming a closed system) and the energy states would remain equal for each particle involved. Just a thought, definitely not suggesting that is true.

[@bleerrgghhhh]

So, the likely hood of tunneling through the wall would be contingent on a huge number of possible paths all the other particles could take? Sort of like entanglement, because knowing one property of the particle in question means you can know nothing about the system as a whole. And the wave function constitutes the uncertainty of that system until you disturb it by measuring it. I like that way of picturing it. Still, I can't pretend I fully comprehend it all.

[@lorenbooker9486]

Say we were at the center of a black hole, and a photon was headed right for our detector. would it be blue shifted or red shifted.

[@garethdean6382]

As far as we know you cannot be at the center of a black hole. You could however be inside one, if it was large enough. In that case the photon would probably be blueshifted since the gravity of the hole is pulling it inwards. However the hole is also pulling YOU in, faster than the photon (since you are already inside and presumably closer than the photon.) This causes a redshift that opposes the blueshift. The closer you get to the center (Assuming a singularity) the more its gravity pulls you and the greater the redshift becomes. At some point I believe it might even overcome the blueshift though I am not quite sure on the math there.

[@oskarliberadzki7220]

At the center we would be past the event horizon which is impossible to achieve.

[@yeeturmcbeetur8197]

+KrazyPlonk I couldn't help but laugh my ass off. That comment was so straightforward it's was infinitely funny.

[@sithsmasher7685]

+Loren Booker If you could put an imaginary detector that is unaffected by spacetime inside the event horizon and read the results, then the incoming light would definitely be blue-shifted. Hope that answers your question. General rule is always: light that moves away is red-shifted and that approaches you is blue-shifted (much like the soundwave of a siren. It's called the 'Doppler effect'. Google it.

[@sithsmasher7685]

***** Hence the word 'imaginary'.

[@Daniel-dc5mr]

I'm finally here, for the past week I've watched and rewatched every single episode one by one until I understood all of them and now I'm here

[@KraylusGames]

Yet another stellar video!

[@TheXZ111]

came here after seeing JWST first image...

[@suecondon1685]

Me too! Really struck by the similarities

[@elidolloff2758]

quantum turtles

[@cherryland3285]

No.

[@pandoradespain3119]

Yes

[@DireSheep]

Yes.

[@Chemeee]

Yes

[@adamtaylor1739]

Yes

[@Tondadrd]

12:30 Thanks for the explenation! Observation is always showed as a ring mesuring what comes thrue it but this way it is more like a circle and it is messured how strong impact does the thing to the circle. It finally makes sence why it have to collapse into one of the possible states once messured. Thanks again!

[@OuterRem]

These videos always make me work harder in class. I really want to catch up to this level of physics as soon as I can.

[@bustaphatty]

You're going to run out of science soon.

[@lozfactor]

Not a chance

[@the145kinga]

Science is not equal to knowledge or physics, science is just own understanding or knowledge and physics and others. There are always missing parts

[@nunyabisnass1141]

Sherlock Holmes etymology fail.

[@Aruthicon]

+Albert Einstein ...oh my god...

[@adolfodef]

Lord Kelvin.

[@antoniolewis1016]

Have I mentioned I love this channel? I love this channel!

[@GabrielACGama]

Could you make a special video about the EM drive? It seems pretty interesting as to how this technology might work and the very complex physics behind it! Btw, I love this channel.

[@pandoradespain3119]

I love this channel so much

[@brit69]

what a time to be alive... PBS Spacetime, you guys are awesome.

[@jtarrats100]

this chanel should have a larger following. great channel

[@myhandsspeak1925]

My favorite chanel. I love it.

[@jimmyshrimbe9361]

Awesome video!

[@suecondon1685]

3:29 Exactly what James Webb is seeing in astonishing clarity.

[@Helixal]

I almost need a PBS kids version of this to understand just the surface level of this concept

[@ufh3478629tegryu]

You should do a series on ER=EPR. It would be really interesting.

[@joshuahiggins4530]

A family friend asked my 4 year old son if he could be any superhero, who would he be? After my other kids said batman, superman and wonder woman....my 4 year old said Matt from Space Time. Watching and learning everyday buddy. Love the show. Addicted. and apparently my son is too.

[@warecb]

I understood this one better than most other ones in this series. Very cool

[@Big73W]

This channel is amazing.

[@TheDJRobbyC]

When you look forward to a science show every week just as much as you look forward to a new episode of Dragonball Super, they're doing something right. Keep up the excellent work! You guys are an inspiration to so many people wanting to enter the many fields of science and technology!

[@3dge--runner]

another killer vid. god i love this channel

[@SkyAce200]

Please, String Theory vs Loop Quantum Gravity episode!!

[@StephenGillie]

OMG death battle plox! Two theories enter, only one theory leaves.

[@jackfadell8848]

I really like that Matt answers all questions. Like giving this amazing answer to: "Can you teleport to the moon?" 9:59 Teachers at school would have shut you down with a detention, but Matt actually anwsered it. Matt, you're awesome!

[@Fleurlean4]

As you were answering the question about tunneling to the moon, I was thinking about the meaning of an "observation", I'm glad I stayed till the end when you dispelled the belief that it only means a conscious being translating a light wave to an image, or something like sound, heat, etc. I'm sure that clears up some confusion about the naming it an "observation".

[@DanielFenandes]

Best series ever

[@marcycarson2130]

Thank you!

[@muaral-rasheed2565]

I simply can't get tired of physics. Thanks Dr. O'Dowd!

[@biznock09]

best show in video format. The fact that this content receives 75k views restores my hope in humanity and scratches my itch for feynman-like lectures on physics for non-physicists. Thank you

[@tooljack4439]

Best one yet!

[@guilemaigre14]

I was studying my Analytical mechanics course, made a break, watched this. Now i'm even more motivated to keep studying. (yes, i'm a physics student) Thanks for the video, very nice !

[@maxwyght1840]

I love how we actually phtsiced reality so hard that we were able to predict EXACTLY how a black hole looks like, and then, years later, we managed to take a pic of a black hole and confirmed our predictions.

[@mastershooter64]

I know right, theoretical physics is insane

[@lautrectheembraced1347]

I absolutely love the IR-telescope from the KSP Interstellar mod, bringing it out to >650 AU to use the sun as a gravitational lens. Even though it doesn't work in game, the challenge is so worth it. Doing science out there almost seems meaningless, where the sun itself is just another star in the (always-) night sky. the concept of time just breaks down since nothing is giving you any context. Really hoping the dev is giving the telescope some much needed love one day.. oh and great vid, as always! You guys always find another interesting topic

[@008pitu]

Hi dear Matt. Your explanations are clear and attract people like me. A dummie in astrophysics. I might conclude that as universe we see through telescopes is full of gravitational lenses . There are regions in our universe where backgrounded galaxies or cumulus or stars are far from its real location due to multiple light coming deflections as light go through multiple gravitational masses.....aligned.

[@merdemoiii-7589]

I find photos of gravitational lensing so amazing

[@howell90002003]

Found this video 2021 after they imaged a black hole. Funny how quickly discovery moves

[@mykeymikel4244]

please upload more videos about new information on black holes

[@tgwthfy]

i love this show, it always leads to a huge existential crisis... in a good way.

[@Tombiz]

Saw your short documentary. I was realy intrested to see more of your work. Is there any chance to see full lenght version of it in the future?

[@RainHNg]

Elite Dangerous has done some great job in mimic these G lensing effect around blackholes... Thanks for another great vid as usual /

[@fatsamcastle]

of all the pbs channels, this one has to be the most intellectually stimulating.

[@grigorizaika8541]

The soundtrack at 9:00 is amasing! Reminds me of the game, Space Rangers: A War Apart. I've never noticed it. Please, insert more of these!

[@poseidonc1259]

Jesus christ! This channel has the most poetic rhetoric I’ve ever heard. Every episode is inspirational beyond belief. Thanks for revealing these discoveries in a manner that allows so many people to more easily comprehend this complex universe!

[@RussianWhiteX]

You should make a video on how we might perceive astronomical distances wrong by the fact that the void of space is not completely empty and there might be few atoms of hydrogen between kilometers, making things look farther than what they truly are.

[@BlkwtrPrk]

Hope you cover the delayed choice quantum eraser experiment. There are other good videos on it, but you do such a great job of explaining everything.

[@FirefoxisredExplorerisblueGoog]

As an astronomy hobbyist, gravitational lensing is another way I look at the universe only for it to peer back at me and say "Heh, I can do what you do but bigger and better". It's the ultimate testament to the malleability of space-time.

[@dudeskidaddy]

Love the ‘mostly, mostly’ poltergeist pull. Great video as usual.

[@AllknowingUnknown]

yupp, Copenhagen, deterministic, *Nods head* I have no idea what he's talking about but I could watch his vids ALL DAY LONG he's so CHILL!

[@f0rtytw016]

I have a question, if the path of light changes under the influence of gravity, does the same principle stand for gravitational waves? Does LIGO correct for this effect?

[@mtruo001]

Can you do more on quasars, pulsars, and black holes. I want every bit of new info or revisualizations. I can't get enough of them holes.

[@spiralsun1]

“The whole universe is a Giant funhouse Mirror” This is my favorite quote of all time!! And space!!! ❤️‍🔥🙏🏻😂

[@AspenEmrys]

mad props to the geniuses who continually extrapolate the implications of established theory!

[@rockwithyou2006]

Similar to what @bunnyofthunder said, Its cool that between this video being made and me watching it today, the image of SMC 0723 Galaxy cluster displaying Gravitational lensing, was taken by the JWST. So cool.

[@mataznuiz]

I luv this stuff