Gravitational Lensing

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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 NOpost 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

9B 34 Dominic
9B 34 Dominic 7 timer siden
so well explained.
RIZE RenNerdClub
RIZE RenNerdClub 21 time siden
JustMoseyinAround Dag siden
*BeetleJuice, BeetleJuice, BeetleJu-*
pokfen Dag siden
About a year to late. On astronomy I had to write a paper about Gravitational lensing. Good thing your video about Black Hole and how it looks like helped. I even linked than video in that.
ronkirk50 Dag siden
I'm absolutely goob smacked!
Sutairn Dag siden
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?
Jacob Sawyer
Jacob Sawyer Dag siden
any day now ... *in the next 100,000 years*
Bo Reed
Bo Reed 2 dager siden
I'm on this guys wavelength so frickn happy you made this rite on man
SKM GAMER 3 dager siden
Do galaxies revolves around some things?🤔
h.s.mani deep
h.s.mani deep 3 dager siden
Looks like the supernova came to bargain.
Big Dogo
Big Dogo 3 dager siden
1:40 "In the next hundred THOUSAND years." :(
Big Dogo
Big Dogo 3 dager siden
Gravitational lensing blows my mind. "Oh, those four galaxies you can see over there? Yeah, they're the same one..." Madness.
Sourav Dey
Sourav Dey 3 dager siden
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??
Alberto Malvido
Alberto Malvido 3 dager siden
One of my favorites video! Thank you so much
Gplayer 3 dager siden
"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?😉😉😉😉
Wandering Dust
Wandering Dust 17 timer siden
That's the actual image. Yes, it already happened and we are only seeing it now. Not exactly a prediction but it takes time for information to pass.
Makaveli Thedon
Makaveli Thedon 4 dager siden
He said stars in nearby universe by mistake. Lol 9:31
Diego Ferreyra
Diego Ferreyra 4 dager siden
Where’s the universe expanding FROM?
a b
a b 4 dager siden
We are so lucky to have Einsten
Unknown Prodigy
Unknown Prodigy 4 dager siden
This is incredible. I don't know what else to say.
Reuben Stern
Reuben Stern 5 dager siden
Makes you realize space is mind blowingly massive.
Reuben Stern
Reuben Stern 5 dager siden
A long time ago In a galaxy far far away?... Proof of Darth sidius and his death star.
arnav sood
arnav sood 5 dager siden
Einstein cross Jesus Christ!
Yuda Dwi
Yuda Dwi 5 dager siden
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?
James Blackstar
James Blackstar 5 dager siden
Good hosting, not everyday i see.
JebClang 5 dager siden
A lens made of "graveity". Yeah right, what sorcery is this? Gravity doesn't even existt
Denzyl Casuela
Denzyl Casuela 6 dager siden
We can predict a supernova but not corona?
Maciej Cholewa
Maciej Cholewa 6 dager siden
Maybe because universe changes but very slowly compared to it's size, when viruses mutate fast, thus we can't predict all mutations.
Harish Dubey
Harish Dubey 6 dager siden
I wish i was not in a city so i could see this rare phenomenon
klaas victor
klaas victor 6 dager siden
This is the most surprising video I have seen in my life! It got me Goosebumps! Humans are incredible to have discovered this!
Bhaskar Bhardwaj
Bhaskar Bhardwaj 6 dager siden
The previous video title was more juicy, at least I feel
Willian 6 dager siden
Panarbore 7 dager siden
absolutely adoreable to be able to work on such topics!
Rama Bandyopadhyay
Rama Bandyopadhyay 7 dager siden
So...The flat earthers are not wrong! They are right in another perspective
Mohd Sameer
Mohd Sameer 7 dager siden
Your videos are lit 👍🏻
Andrey Sergeev
Andrey Sergeev 7 dager siden
Thank you! Ah...I thought it will be about building a lens for a gravity laser. But this is very interesting too.
Phantomrocks #phani
Phantomrocks #phani 8 dager siden
Meanwhile supernovas image giving us a creepy smile at 6:25
yogesh jangid
yogesh jangid 8 dager siden
Can anyone tell me how light is traveling in a curved path..I have learned that light travels in straight line.
Andrey Sergeev
Andrey Sergeev 7 dager siden
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.
John Berry
John Berry 8 dager siden
Wait til' the UK viewers find out that the 5000 pound Techie Bundle actually weighs 5000 pounds (
Mahmoud Mostafa
Mahmoud Mostafa 8 dager siden
it was Isaac Newton.
DevN 8 dager siden
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 ;)
DevN 8 dager siden
and millions of people r convinced they know it all from 1 holy book.
Trying1 /
Trying1 / 8 dager siden
It sucks
Ryan Johnstone
Ryan Johnstone 9 dager siden
amazing !!!!
Chris Methot
Chris Methot 9 dager siden
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.
Chris Methot
Chris Methot 6 dager siden
The first answer might be how could we see galaxies merging if there were only one.
Kinnari Bhalerao
Kinnari Bhalerao 9 dager siden
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!!!🌌
Muhammad Hamza Tahir
Muhammad Hamza Tahir 9 dager siden
Space has always been an inspiration for me. Hubble is fascinating my heart day by day.
Gabriel Ferrão
Gabriel Ferrão 9 dager siden
Star: Betelgeuse Me: Be tel gese Veritasium: Bettle Juice
FezRez 9 dager siden
Its incredible how much info scientists can extract from these tiny little smears of light
Wu Chenglin
Wu Chenglin 9 dager siden
1:32 beetlejuice
Prince Fel Ezekiel R. Licardo
Prince Fel Ezekiel R. Licardo 9 dager siden
It's fascinating that how much information astronomers can get from pictures, from a normal person, not so much.
Dennis D
Dennis D 9 dager siden
And here I struggle getting a decent pic of my dog.
Nae Dolor
Nae Dolor 10 dager siden
Is this one of the first generation stars in the universe ?
David M. Johnston
David M. Johnston 10 dager siden
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 :-)
Learning Unity
Learning Unity 10 dager siden
did you break the space time continuum? no worries, just seal it with FLEX TAPE! *slaps tape on spacetime*
Ninty 9
Ninty 9 10 dager siden
Only Legends Know the Title of This Video Has Been Changed
Mr. Thomas A. Anderson
Mr. Thomas A. Anderson 10 dager siden
I love your videos! You make them entertaining and you have a catchy voice.
Soumen Bhattacharya
Soumen Bhattacharya 10 dager siden
Varitasium and 3brown1 blue are best ones also PBS videos too
Fredrik Attila Farkas
Fredrik Attila Farkas 10 dager siden
Does this mean that light can «move» an object aswell? Like airflow over a wing creating lift?
Mohammed Shaik
Mohammed Shaik 10 dager siden
3:48 Damn that looks creepy lmao
Balubish Tech
Balubish Tech 10 dager siden
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. 😎✌
seachangeau 10 dager siden
Oh its such crap.
Jimmy Johns
Jimmy Johns 11 dager siden
Wow, this really opens your mind! It’s like taking drugs OMG. Loved it!
Mohd Shariq
Mohd Shariq 11 dager siden
6:29 Seems deep space is smiling on us!..with a cigarette in its mouth! 😵
Lar Wor Tsomv
Lar Wor Tsomv 11 dager siden
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.
raedtrab 11 dager siden
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.
Kumar Digvijay Mishra
Kumar Digvijay Mishra 11 dager siden
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.
sokin jon
sokin jon 11 dager siden
The Real Question: How do scientists notice a tiny dot of a star in the middle of so many blurs and other stars?!
A G 3 dager siden
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.
Aadil Peer
Aadil Peer 3 dager siden
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:)
Sourav Dey
Sourav Dey 3 dager siden
It’s their passion... they love to do that.. isn’t that amazing??
jacob olson
jacob olson 6 dager siden
It's more like yeah there's a lot of stars. There's a lot of scientists and telescope
ilkercan Kaya
ilkercan Kaya 11 dager siden
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.
Amadley Gaming
Amadley Gaming 12 dager siden
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
Ruben Anthony Martinez
Ruben Anthony Martinez 12 dager siden
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.
sokin jon
sokin jon 11 dager siden
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
Gagandeep Singh
Gagandeep Singh 12 dager siden
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
CyberBeast66 12 dager siden
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?
Ry V.
Ry V. 12 dager siden
Space time would seem to not be homogenous in the universe thus various gravitational lensing effects.
Ayoub Berrada
Ayoub Berrada 12 dager siden
6:30 creepy smiley face
Charles Rogers
Charles Rogers 12 dager siden
My brain hurts now
MH Promit
MH Promit 12 dager siden
He is cool🤯
Aditya Rayapureddy
Aditya Rayapureddy 12 dager siden
Can you please make a video that proves Universe is infinite?
RobloxGamez 12 dager siden
6:31 oh a luck smiley
Chitra Lekha
Chitra Lekha 12 dager siden
Splendid and extraordinary video on lensing. Made me case study it intuitively. May god bless you.
POETRY TRIAL 12 dager siden
Before I thought something else After - ohh so this is what happens!
bilishu aliss
bilishu aliss 12 dager siden
able to travel the galaxy/ies but have died off millions/billions years ago?
jake friesen
jake friesen 12 dager siden
Great video, but all this astronomy talk is so pointless really. How about giving the wasted money to buy food for the hungry.
bilishu aliss
bilishu aliss 12 dager siden
I hope Fasthosts got better in the last 10 years, because they used to be shockingly bad!
Thinkclear Bell
Thinkclear Bell 13 dager siden
I'm glad we have Derek as the cosmological information lense in our time. 1000 years later, he'll reappear on an other planet
aola wili
aola wili 13 dager siden
can sit still through this entire video.. Well done man.
Gacheru Mburu
Gacheru Mburu 13 dager siden
Sveredian 13 dager siden
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.
Nevermore77 14 dager siden
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!
aola wili
aola wili 13 dager siden
Tony Stark: No amount of money has ever bought a second of time. Veritasium: How about the cost of Hubble telescope?
will2see 14 dager siden
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.
Shablé 14 dager siden
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
miko foin
miko foin 14 dager siden
1:40 "In the next hundred THOUSAND years." :(
victor guzman
victor guzman 14 dager siden
This guy can convince me to take the blame of crimes i didn't even commit.
commodityHelp 14 dager siden
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.
Daniel Kunigan
Daniel Kunigan 14 dager siden
The supernova might have happened 9.3 billion years ago, or - depending on the speed of light in this direction - maybe it happened yesterday.
miko foin
miko foin 14 dager siden
In a few ... Me - ohhhhh yeahh boi.. Hundred thousand years.....
Ilshat Ahatov
Ilshat Ahatov 14 dager siden
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?
mikenco 14 dager siden
I hope Fasthosts got better in the last 10 years, because they used to be shockingly bad!
JakubH 15 dager siden
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?
No Expert
No Expert 15 dager siden
The Earth is FLAT 🕳
Nathan Maxson
Nathan Maxson 15 dager siden
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
FlyingSavannahs 14 dager siden
iOS or android?
omar 717
omar 717 15 dager siden
im in year 7 and i am finding this the most interesting topic i have ever learned thanks for teaching me :)
Robert Hilden
Robert Hilden 15 dager siden
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!💛
Jayson Burke
Jayson Burke 15 dager siden
“You will be able to see beetle juice’s supernova” Me: “Hmm”
bilishu aliss
bilishu aliss 15 dager siden
Tony Stark: No amount of money has ever bought a second of time. Veritasium: How about the cost of Hubble telescope?
raedtrab 11 dager siden
Tony Stark approved the joke :)
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