Gravitational Lensing

Dipublikasikan tanggal 20 Okt 2020
In 2015 astronomers successfully predicted the appearance of a supernova within a couple weeks. How did they do it? Win your Ultimate Tech Bundle by entering Fasthosts’ Techie Test here: (Competition now closed) This video was sponsored by Fasthosts.
Special thanks to Geraint Lewis for consulting on gravitational lensing. Check out his ID-tv channel: and books:
The supernova image in the thumbnail is from my documentary, Uranium: Twisting The Dragon's Tail. Check it out here:
P. L. Kelly et al.
Predicted properties of multiple images of the strongly lensed supernova SN Refsdal
Masamune Oguri. Monthly Notices of the Royal Astronomical Society: Letters, Volume 449, Issue 1, 01 May 2015, Pages L86-L89,
Multiple Images of a Highly Magnified Supernova Formed by an Early-Type Cluster Galaxy Lens
Patrick L. Kelly et al.
"Refsdal" meets Popper: comparing predictions of the re-appearance of the multiply imaged supernova behind MACSJ1149.5+2223. T. Treu et al.
Irwin I. Shapiro (1964). "Fourth Test of General Relativity". Physical Review Letters. 13 (26): 789-791. doi:10.1103/PhysRevLett.13.789
Irwin I. Shapiro; Gordon H. Pettengill; Michael E. Ash; Melvin L. Stone; et al. (1968). "Fourth Test of General Relativity: Preliminary Results". Physical Review Letters. 20 (22): 1265-1269. doi:10.1103/PhysRevLett.20.1265
Research & Writing by Stephanie Hamilton, Ralph Crewe, Petr Lebedev, Derek Muller, and Jonny Hyman
Animations & VFX by Jonny Hyman & Ivàn Tello
Thanks to Jaime Portsmouth for his gravitational lensing simulator and help enabling it to render simulations.
Supernova simulations courtesy of Adam Burrows
Numerous hubble images by Hubble Legacy Archive, NASA/ESA/STScI
Numerous images by ESO / NASA


  • I'm absolutely goob smacked!

  • WIth this information we should be able to create a concrete equation on how much our movement is effecting redshift, why do we not see this equation when calculating the Hobble Constant?

  • any day now ... *in the next 100,000 years*

  • I'm on this guys wavelength so frickn happy you made this rite on man

  • Do galaxies revolves around some things?🤔

  • Looks like the supernova came to bargain.

  • 1:40 "In the next hundred THOUSAND years." :(

  • Gravitational lensing blows my mind. "Oh, those four galaxies you can see over there? Yeah, they're the same one..." Madness.

  • What I thought of this ?? Wowweee... please teach me how did they measure the trajectories and times so accurately.... what math is behind this?? If they published a paper??

  • One of my favorites video! Thank you so much

  • "In 2015 astronomers successfully predicted the appearance of a supernova within a couple weeks." Technically, that was not successfully predicted a supernova(the event happened at the end life circle of the star far far away), just predicted what image(what we would see from the Earth) the Hubble telescope would get according to the video, which were two different things. Am i right?😉😉😉😉

  • He said stars in nearby universe by mistake. Lol 9:31

  • Where’s the universe expanding FROM?

  • We are so lucky to have Einsten

  • This is incredible. I don't know what else to say.

  • Makes you realize space is mind blowingly massive.

  • A long time ago In a galaxy far far away?... Proof of Darth sidius and his death star.

  • Einstein cross Jesus Christ!

  • Soo... Does it mean that if we have a telescope sharp enough to see individual planet on galaxies far far away, and strong enough to catch light reflected from earth, we can technically see our past?

  • Good hosting, not everyday i see.

  • A lens made of "graveity". Yeah right, what sorcery is this? Gravity doesn't even existt

  • We can predict a supernova but not corona?

    • Maybe because universe changes but very slowly compared to it's size, when viruses mutate fast, thus we can't predict all mutations.

  • I wish i was not in a city so i could see this rare phenomenon

  • This is the most surprising video I have seen in my life! It got me Goosebumps! Humans are incredible to have discovered this!

  • The previous video title was more juicy, at least I feel

  • Amazing

  • absolutely adoreable to be able to work on such topics!

  • So...The flat earthers are not wrong! They are right in another perspective

  • Your videos are lit 👍🏻

  • Thank you! Ah...I thought it will be about building a lens for a gravity laser. But this is very interesting too.

  • Meanwhile supernovas image giving us a creepy smile at 6:25

  • Can anyone tell me how light is traveling in a curved path..I have learned that light travels in straight line.

    • I don't know what does really moving straight means but let's say it is moving while being not affected (accelerated) by any force. That means nothing is changing the momentum of a photon I guess. I would naively say that light indeed travels in a straight line through space but if you bend space itself then that line is no longer straight. Photons have no mass - gravity does not pull them as regular objects with mass. The gravity is bending space and time therefore anything in that space is bent too. You can draw a straight line on a paper sheet then crumple that paper - so the line will be straight relative to the paper but not to the world around it. That way path of light is curved. That means that the direction of a photon is changed - so its momentum. So I will guess you need to spend some gravitational energy on that. But what is the least possible degree of that curvature? That I don't know. If you look at curved lines on a display they are made from pixels - so any circle is in fact a sum of small straight segments. If that is the case for space curving then there are always some parts of space where light indeed travels in a straight line - because it can't be affected by any force. If not then you can arrange a bending of any degree at any place so it's not necessary to have any straight segments at all.

  • Wait til' the UK viewers find out that the 5000 pound Techie Bundle actually weighs 5000 pounds (

  • it was Isaac Newton.

  • when my boss catches me in a foto somewhere else..can i explain that its perhaps gravitational lensing...both time and place r incorrect..i was actually working at home ;)

  • and millions of people r convinced they know it all from 1 holy book.

  • It sucks

  • amazing !!!!

  • This just reinforces a question I have had for over 10 years. Using the discipline of the null hypothesis prove to me that every galaxy you see in the cosmos isn't the same galaxy seen from a different angle at a different time? The cosmos as a hall of mirrors.

    • The first answer might be how could we see galaxies merging if there were only one.

  • Gravitational lensing is one of my favourite concepts!! And this is amazing!!! Loved the way the video is made. Seemed like we are in space!!!🌌

  • Space has always been an inspiration for me. Hubble is fascinating my heart day by day.

  • Star: Betelgeuse Me: Be tel gese Veritasium: Bettle Juice

  • Its incredible how much info scientists can extract from these tiny little smears of light

  • 1:32 beetlejuice

  • It's fascinating that how much information astronomers can get from pictures, from a normal person, not so much.

  • And here I struggle getting a decent pic of my dog.

  • Is this one of the first generation stars in the universe ?

  • Great video Derek, thank you for teaching me so many interesting things! By the way, I'm just thinking... I've been following you since 2013. Most of my closest friends I've known for less time than that. And your videos continue to amaze me! Take care Derek, and keep up the excellent work! (no pressure :-)

  • did you break the space time continuum? no worries, just seal it with FLEX TAPE! *slaps tape on spacetime*

  • Only Legends Know the Title of This Video Has Been Changed

  • I love your videos! You make them entertaining and you have a catchy voice.

  • Varitasium and 3brown1 blue are best ones also PBS videos too

  • Does this mean that light can «move» an object aswell? Like airflow over a wing creating lift?

  • 3:48 Damn that looks creepy lmao

  • This is mindblowing sorta. Also makes me feel incredicle dumb compared to actual smart people. I knew math was important and read electronics in high school so did alot of math. But counting math that bends light by gravity and mass vs distance and time to the object and beeing able to count that far back including by my guess a ton of gravity bends/warps between stars, galaxies of the fabric of space, with an end result of different years and times to the day, which you can view the same exact thing happening. 🤯 Now thats some hardcore math right there.🧠 Also how isnt Einstein an Emoji by now. 😎✌

  • Oh its such crap.

  • Wow, this really opens your mind! It’s like taking drugs OMG. Loved it!

  • 6:29 Seems deep space is smiling on us!..with a cigarette in its mouth! 😵

  • What if, as the universe expands, the general speed of light increases? Meaning, if we had a window into the future we would observe everything moving faster. This does not affect the Doppler shift, which only cares about the 'stretching out' of light as it moves, since all 'parts' of light will be speeding up at the same time so there will be no differential that would be evidenced in the color shift. However it may 'speed up' other observable cosmic activity, meaning light reaches us faster than expected if it were moving at a 'constant' speed. Therefore the calculated expansion rate of some methods gives a lower result.

  • Am I still on time to answer the question? Which is actually wrong it was Sir Isaac Newton who answered to RICHARD BENTLEY (theologian and philologist) “That gravity should be innate, inherent, and essential to matter, so that one body may act upon another at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it. Gravity must be caused by an agent acting constantly according to certain laws; but whether this agent be material or immaterial, I have left open to the consideration of my readers” this was in answer to And what Richard Bentley wrote that generated Sir Isaac Newton’s answer was And as for gravitation, tis impossible that that should either be coeternal and essential to matter, or ever acquired by it. Not essential and coeternal to matter; for then even our system would have been eternal (if gravity could form it) against our atheist's supposition and what we have proved in our last. For let them assign any given time, that matter convened from a chaos into our system, they must affirm that before the given time matter gravitated eternally without convening, which is absurd. {Sir, I make account, that your courteous suggestion by your last, that a chaos is inconsistent with the hypothesis of innate gravity, is included in this paragraph of mine.} and again, tis unconceivable, that inanimate brute matter should (without a divine impression) operate upon and affect other matter without mutual contact: as it must, if gravitation be essential and inherent in it.

  • Gravitational lens smears images from Hubble telescope. What is the cure for distortion? Apart from making intelligent assumptions/guesses, there seems to be no other method to give a clearer image.

  • The Real Question: How do scientists notice a tiny dot of a star in the middle of so many blurs and other stars?!

    • They don't. No, but with the power of modern technology, devoted people, and some of the smartest people on the globe many things are possible.

    • Unstoppable curiosity does it all...I am more surprised to know that there is actually stuff like time dilation.5 years out from physics and I thought it is all theoretical.Guess that's why flat earthers still exit.Might be of my kind:)

    • It’s their passion... they love to do that.. isn’t that amazing??

    • It's more like yeah there's a lot of stars. There's a lot of scientists and telescope

  • I want to live hundreds of years to observe and study all the knowledge in universe. Sadly humans life span isn't long enough for such thing. I want to discover new planets, understand what is behind this universe. I don't wanna die without knowing why I was here.

  • Veritasium pumping out superlative quality content is one of the rare positive things about 2020 - How do they do it? That's the real mystery

  • Gravitational lensing maybe a misinterpretation, this lensing could also be produced by cosmic space, becaused *space is not completely empty-it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium.* It is the space medium itself that causes this light refraction phenomena. Then it becomes understandable that galaxies tend to form a higher density of this space medium ( Halo) , which produces the lensing effect, and has nothing to do with gravitational fields.

    • So here is a neat trick folks! This will help you understand the universe and that Big Bang everyone keeps babbling on about. Take a stone, throw it in the pool, watch the rippl

  • 30 October 2020 - I started to study stars and supernova. 14 November 2020 (today) I am watching this video. 11 December 2020 is my birthday. Now skip to 2:30

  • I don't know why I just thought of this question weeks after the video, but if gravitational lensing can allow us to see the same light source appear at multiple points and over different time periods, how can we know a lot of what we see in the sky isn't lensed from somewhere or someWHEN else? We would be counting some of the pinpoints of light in the sky multiple times, skewing our data right?

  • Space time would seem to not be homogenous in the universe thus various gravitational lensing effects.

  • 6:30 creepy smiley face

  • My brain hurts now

  • He is cool🤯

  • Can you please make a video that proves Universe is infinite?

  • 6:31 oh a luck smiley

  • Splendid and extraordinary video on lensing. Made me case study it intuitively. May god bless you.

  • Before I thought something else After - ohh so this is what happens!

    • able to travel the galaxy/ies but have died off millions/billions years ago?

  • Great video, but all this astronomy talk is so pointless really. How about giving the wasted money to buy food for the hungry.

    • I hope Fasthosts got better in the last 10 years, because they used to be shockingly bad!

  • I'm glad we have Derek as the cosmological information lense in our time. 1000 years later, he'll reappear on an other planet

  • can sit still through this entire video.. Well done man.

  • 🤔👍

  • One thing Veritasium talks about in a future video is how currently we can't confirm the speed of light in one direction. Therefore, given that we don't know if the speed of light is the same in all directions doesn't that make our current methods of measuring universal expansion inherently flawed? They would be working upon an assumption that hasn't been confirmed, so like light, the universe could be expanding at different rates given the direction you are facing.

  • So here is a neat trick folks! This will help you understand the universe and that Big Bang everyone keeps babbling on about. Take a stone, throw it in the pool, watch the ripples expand faster and fast and faster until they reach the edge of the pool! Did you notice how they kept getting faster and faster? No? Well guess what, I just lied to you. THINK ABOUT IT!

    • Tony Stark: No amount of money has ever bought a second of time. Veritasium: How about the cost of Hubble telescope?

  • But you didn't explain how this latest method of measuring the Hubble constant works. How you get the Hubble constant by measuring the time delay between different images of a supernova? Now, I'll have to check all the referred articles in the description.

  • 6:27 the universe is smiling upon veritasium, Derrick müller is a genius, yes I put the diaerisis in last name as an understanding of observation as Derrick does for all of us. Thank you sir Derrick, your work teaching us troglodytes is appreciated

  • 1:40 "In the next hundred THOUSAND years." :(

  • This guy can convince me to take the blame of crimes i didn't even commit.

  • Our mind is set to measure things , compare different objects for getting an understanding of measure. So we invent Mathematics. But in the course of human understanding of physical world and development of Mathematics , we come across a mathematical identity i.e., infinity . If we divide any number by Zero , then it is said 'INFINITY'. AND any number is divided by smallest decimal fraction, it starts increasing. It can be increased unlimitedly .If you divide 1/3 and the result is unlimited. I think here is the answer of the VASTNESS OF UNIVERSE.

  • The supernova might have happened 9.3 billion years ago, or - depending on the speed of light in this direction - maybe it happened yesterday.

    • In a few ... Me - ohhhhh yeahh boi.. Hundred thousand years.....

  • How do you know something happened "x billion years ago"? What if light travels instantaneously in our direction and half the speed back to the supernova?

  • I hope Fasthosts got better in the last 10 years, because they used to be shockingly bad!

  • Can you explain, If we see stuff that happened millions/billions years ago, does it mean that the universe is dying, and once there could have been intelligent beings that were able to travel the galaxy/ies but have died off millions/billions years ago?

  • The Earth is FLAT 🕳

  • All these people commenting a bunch of stuff that sounds smart and I'm over here trying to figure out how to turn on the flashlight on my phone

  • im in year 7 and i am finding this the most interesting topic i have ever learned thanks for teaching me :)

  • I swear I watched this before! I feel like this is waaay easier to understand than the first time you explained this stuff. Great video!💛

  • “You will be able to see beetle juice’s supernova” Me: “Hmm”

  • Tony Stark: No amount of money has ever bought a second of time. Veritasium: How about the cost of Hubble telescope?

    • Tony Stark approved the joke :)

  • This guy can convince me to take the blame of crimes i didn't even commit.

  • english natives be pretending like loanwords in english don't follow general rules

  • 6:25 Space Face

  • The Hubble Constant, H, is not really a constant. The Hubble ‘constant’ H is defined thusly: H = 1/a (da/dt) Where a = scale factor