The Strange Universe of Gravitational Lensing

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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

Comments by:

AyyElMao

Błażej Michalik

Flynn Kruchell

Mystyc Cheez

[BunnyOfThunder]

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

[Diogie]

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

[Darxide]

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.

[keronplug]

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

[alextaramas]

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 .

[nthanfv]

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

[vorea]

Does anyone else love the background music of these videos?

[nwojwbk]

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

[ChrizoPrime]

This gentleman is brilliant, and so is his beard.

[Daniel-dcmr]

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

[whatthefunction]

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.

[jamboni]

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

[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 ;)

[keenanasbridge]

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

[aliciabaumgartner]

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.

[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.

[ginzburgnathan]

fucking Einstein, how can someone be that brilliant.

[juniorcyans]

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!

[haydenhouse]

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 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!!!

[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!