Is light a wave or a particle? | Great debates in physics

One of the most famous debates in all of Physics is one that spanned over four centuries and eventually led to Einstein and Bohr debating for most of the 20th century. It was all about the very nature of light - is light a particle (as Newton had insisted) or is light a wave (as people like Young and Maxwell insisted)? It was eventually a problem that quantum physics would solve...

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👩🏽‍💻 Dr Becky Smethurst is an astrophysicist researching galaxies and supermassive black holes at Christ Church at the University of Oxford.

[DrBecky]

Thanks to everyone pointing out my mistake in the comments! I incorrectly stated that Young did the double slit experiment with electrons.Young wasn’t the one to do the experiment with electrons - that was Davisson & Germer in 1927 right before the 5th Solvay conference. I think I’ve misread my notes somewhere when I was prepping this video because electrons weren’t even discovered until the end of the 19th century! I seemed to have smushed result in with Young’s experiment in 1801 when I was filming by accident. I don’t really write scripts just make some notes and chat around them, and sometimes this happens! Apologies that neither me or editing Becky spotted that one 🤦🏻‍♀️

[JulesvanPhil]

My teacher once came up with the analogy of a cylinder: looking from the top it looks like a circle and from the right like a rectangle but actually it is none of both. It just depends on the way you encounter it, how it appears to you.

[johnthompson]

So that's why they call themselves particle physicists, but are really wave physicists when no-ones looking?

[mpart_woodlathe-stuff]

I wish I had access to you and your kind of internet teaching(?) 55 years ago when I was 13. Stay safe. -Mike😷

[Payneview]

My favourite answer to the question "Is light a wave or a particle?" is "Yes.".

[Charis_Code]

The way you can explain experiments and concepts in such a simple and understandable way and at the same time be sooo cientifically precise is amazing! I cannot imagine how hard you work for that, especially being part of Oxford and having the pressure of so many intelligent colleagues watching your videos. Youre an amazing person for making the videos you do! Cheers from Brazil!

[juanbernardez]

I always get a little 'giddy' when I see that famous picture from Fifth Solvay Conference.

[germancuervo]

-Is light a wave or a particle?
-Yes
-Yes what?
-Yes, ma'am

[juanvia]

You sing very well. Make a duo with Sabine Hossenfelder and compose a song "The waves are redshifting in the dus<t|k>"

[MaxG]

I know that I'm months too late for this video but I have just discovered your channel a few days ago. I am enjoying your videos tremendously. When I was in 9th grade, I took an Astrophysics summer camp and one of the topics was particle/wave duality. One of the clearest memories of that time for me is the fascination that the lecture spawned within me and the love for science that grew from that.

[robertholmes]

Love the bloopers! Please don't stop including them! Thanks. X

[Zestyclose-Big]

2:45 I've seen this in physics textbooks a few times but I think this is the first time it's kind of _really_ cliked, wow thanks!

(I actually doubt we never got shown this kind of experiment at school at some point but if we indeed did I guess it wouldn't have been memorable enough)

[vishal]

Looking forward for the next video, this was so intresting... 👏

[airmakay]

The picture at 19:34 - wow. Despite the great Erroneous Electron Experiment Scandal of 2020 this was a fine video. Please do more of these. I so agree, an understanding of the history of a scientific idea is critical in the overall comprehension of the idea itself. Historical perspective of application of the scientific method is vital, and is often makes for a cracking good story!

[shubhamsingh]

I am so in love with the way she explain things ❤

[ybbcgfe]

What a great offer from you re asking you to cover a topic. Thank you so much!! Following on from your double slit vid, can you do one on Bell’s Theorem and explain how this shows that the uncertainty in Quantum Mechanics is not caused by our lack of knowledge about hidden variables but is fundamental part of the universe and maybe explain the concept of non-locality as well?

I can hardly wait!

Thank you.

David

[francoism]

French guy here: "de Broglie" is pronounced "de Breuille". And yes, it doesn’t make any sense, even for French people !

[TheNameOfJesus]

@12:41 I'm uncertain if that's a picture of Heisenberg, but @12:54 I am sure that Max Born is the grandfather of Olivia Newton John, who sang a lot about physics in her 1981 #1 hit "Let's get Physics all". Einstein visited Born's house for dinner often, but he died in 1955 and Olivia was born in 1957 so they never met, but Olivia literally followed in Albert's footsteps in Max's house.

[geraldfrost]

Is Dr Becky a genius, or beautiful?
Why not both!

[cjphelp]

I can't smash enough likes for this video. Great coverage of both the technical and human sides of this progression of ideas and evidence.