I did the double slit experiment at home

Supported by Screen Australia and Youtube through the Skip Ahead initiative.

Safety and where to get the supplies:

I would love for you to try this experiment but please be careful with the lasers. If you're going to buy a green laser then it's crucial that you buy a proper one. Green lasers emit light a lot of invisible IR light and in cheap lasers this often isn't filtered out well. Blue/ violet lasers can also be dangerous for another reason. Our eyes are terrible at seeing these wavelengths, so the laser will look much less strong than it is, which means you might be playing with a dangerously strong laser without knowing it. Red lasers are generally the safer bet. I saw the effect I was looking for even when I used cheap ~1mW red lasers, so it will still work for you!

Another way to buy lasers that are eyesafe is to get them from school science lab suppliers.

(Note: in some countries it's illegal to sell lasers over 1mW. Please check the laws where you live. In the USA the limit is 5mW)

The smoke machine I got used glycerol. I’m very suspicious of breathing in that smoke though, especially since the room can't be too well ventilated or it won't work. Fine particulate matter is a serious health risk in general so even though glycerol is nontoxic I think it may still be hazardous to inhale. I recommend wearing an airtight n95 mask or similar while doing this experiment.

It found it a bit tricky to source the double slit cheaply in Australia- your best bet might be a science lab supplier. In the USA you can get it on amazon though.

Video credits:

Thank you to Screen Australia and Google Australia for funding this project, and to the wonderful people at Screen Australia who helped me throughout the process.

Thanks also to all my beta testers (aka friends)!!

[LookingGlassUniverse]

If there are variations you’d like to see, let me know, I’ll film them as a short :)

[eduardpertinez]

You forgot to mention the most important point. And that is that the experiment works the same even when you send the photons one by one. The interference could be explained both by light being only a wave and by light being particles that somehow follow a pattern when they bounce against each other. But the magical point of the double slit experiment is that sending photons one by one, the interference pattern arises in the detector screen even when there is no possibility for the photon to interact with any other photon.

[cmvamerica]

Einstein said: “ It’s a miracle that curiosity can survive formal education.” . It takes curiosity to be able to do science. Keep up the good work.

[alien.intergalactic]

You're the first person that has shown this without graphics. I love it.

[ranjansingh]

Absolutely marvellous! You can be taught by a teacher, a lecturer, through a book - but nothing brings it to life like doing the experiment yourself! Thank you for taking us on the journey.

[kunk]

You literally woke up my curiosity over quantum mechanics which I buried long ago for my software career. The demo of double slit experiment is like never before. You're the main reason I bought QM by J.Griffiths textbook a year back. You inspired me a lot. Keep up the amazing work. Love you.

[DougKendig]

Outstanding! By far the most definitive example I have ever seen.. and I am 60 yrs old.. Wow.. well done young lady.

[timtigerjazz]

I really like how you personalized this experiment and revealed how you now can start to see the wave character of light as real from getting your self directly involved and finding the facts for yourself through direct observation of real experiments in real time etc

[arifsaifee]

This is one of the best (if not the best) video I've come across that explains the wave/particle duality in a way that even a layman can understand. Well done!

[sherylbegby]

This was fantastic. I love your skepticism. It's amazing to see a physics PhD admit they're not entirely, viscerally, convinced by the wave theory of light, and then work out whether they can find a way to convince themselves either way. It is seeing the scientific process in action, and it's a beautiful thing. Thank you.

[tibees]

Love this video! Your choice of books for holding up the ripple tank perfectly summarise the journey you are taking us on to understand the weirdness of reality. Well done! 💗

[JeanYvesBouguet]

How is it possible that it is the first time I see a video in your channel? I absolutely love this. You are amazing and deserve a much much larger audience! Thank you for being here on YouTube and sharing your love for science.

[ObviouslyASMR]

That's probably the coolest DIY experiment I've seen on YouTube, and those visuals.. wow

[thirdeyyye]

I’ve watched many videos on this subject before, but this is honestly the very first one I’ve seen that has helped me gain the most understanding about the double slit experiment…so, thank you for that! What an excellent video.

[Pastisas]

As a PhD student in experimental physics it was fun for me to watch a theoritical physicist discovering that experiments are fun! :)

[A-moose]

As someone who has spent way too much time thinking about the double slit, this was an amazing video. Thank you.

[Sunflower-rgnt]

you have no idea about how much this video changed my perception of light. thank you so much. your curiocity is appreciated

[mfatihakal]

I don't write comments very often but to this one I really had to. 14:05 and 14:20 are simply jaw-dropping. You are really a very good experimentalist, I never really imagined that I could see light as a wave with plain eyes as it propagates. Thank you very much, it was simply a perfect visualization.

[demonsheadshot]

The ability to see something physically and practically that you've only seen or heard theoratically is such a surreal moment like THIS is infact a real thing, it exists, I am seeing it with my own eyes and not just some mathematical equations/models, as someone who is curious about literally anything I get my chance at, this was pretty amazing

[lucienberl]

The animation with you in the boat saying "what wave"? Made me laugh. I think I love you. 😁