Gravitational Lensing

In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative.  It tells us that what we experience as gravity can be most accurately described as the bending of space itself.  This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space.  This is works in a way analogous to a lens (and hence the name).  In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

Related video:

[cortster]

I love Fermilab. Both the YouTube channel and the actual lab. You are all awesome. Keep changing the world!

[dhertsens]

I had a tough time getting my head around this lensing effect, in particular when it forms a ring. In comes doc Lincoln and explains it perfectly. It all makes sense! Thanks, doc!

[DavidODuvall]

How many people noticed what was written on Einstein’s chalkboard in the video at 3:13?  Once again, thank you Dr. Lincoln for this video and the touch of humor.

[Madi-dtbo]

The man doing the narration is like the overly happy science teacher in middle school who everyone loved because they were so passionate about science and loved their job. So PURE

[earthtrigger]

"Want to be as smart as me? Watch Don's videos!" - Albert Einstein

[SabryTunnelVision]

Don, I have a question about gravitational lensing and the observations of the ultra deep field of distant galaxies.

If we consider how far the light has traveled and also accept that the light can be bend (and clearly we even are assuming this takes place)
How can we be sure that this light is still close enough to come from straight ahead?

I know we have been looking for patterns to exclude this idea but we are talking about astronomical distances so hard to even visualise.

Could it be that the light actually gets bent many small times making us look back at ourselves?

I know this sounds weird, but sometimes I wonder... we are talking about enormous distances and a lot is possible...

[OSUHARDINGATECHNICEXPERIENCE]

I absolutely love this channel and all the video content. I know it's mostly based on quantum physics and particle physics, but a video on black holes would be great!

[dtvm]

An "Old" Retired Welder with less than a tenth grade education now understands Gravitational Lensing. How cool is that? Thanks, Dr. Don and all you Fermites.

[Mastikator]

"Want to be as smart as Einstein
Don't watch videos"

Damn you got me good Fermilab.

[Saki]

Guys, I am the first to comment from my perspective. Let it be known that Einstein was right when I wrote this first comment in my reference frame. May everyone else behind me be lensed through my gravitational excellence into a ring around my godly figure.

[zack_]

3:21 - Everything said here makes sense, EXCEPT the 'enlarged pseudoimage' at the more distant farther background. Human see the lensinged circular image around the foreground object so there is no need to be projected to the background behind the imitting object in order to see it. This happens ONLY w/ a projector replacing the observing human.

[ronadespabiladeras]

Good day. I am a graduate student of Bicol University (Philippines) and I am currently writing my thesis on the use of flipped classroom in teaching. Your video is very informative and is suited to the level of my learners. Please allow me to use it in my study. Thank you very much.

[saintloren]

I am working on a different concept of Gravity Lensing. I am bending laser beam by a Flywheel. I use multi pal mirrors (in a strangle pattern) to multiply the angle of the bend of the beam vs static event of the flywheel. I am learning Rotation effects gravity near field. I feel with enough flywheels and a gravity detector I can build a gravity scope. Saint Loren Feb 2016

[merlepatterson]

Desert heat waves don't bend space time but they sure do screw up the distant photons trying to make their way through them.

[cgaccount]

This Einstein guy you mentioned sounds pretty smart 😉

[danalaniz]

Great explanation! I love Einstein's message to us on the blackboard. I'll definitely keep watching your videos.

[sambhrantagupta]

"Watch Don's videos"😂😂amazing video as always

[menonijk]

I have a question please help me out, how do we know the correct position of the star next to the sun in the first place to know that its position is shifted due to gravitational lensing as observed by the astronomer : Arthur Eddington. Many thanks in advance

[captainawasome]

A gravitational lens gives you two images. Einstein's Cross gives four. Some other times it give circles instead?

[ParmMohan-usrn]

What an honor it would have been to be in the presence of Einstein. Brilliant!