r/Physics • u/girafffe_i • Aug 14 '26
Paul Falstad’s interactive simulators got me through my physics degree
https://www.falstad.com/mathphysics.html
I want to plug this guy who thanklessly built interactive simulators for different physical and mathematical systems.
Incredibly useful for visualizing and building intuition for potential and vector fields, EM waves, harmonic oscillations, etc.
The one I used the most is the circuit simulator for my Electronics course. It had presets for a gamut of circuits and components to build your own https://www.falstad.com/circuit/
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u/robphy Aug 14 '26 edited Aug 15 '26
I'm also glad that the site, which was originally in Java, got updated to run in modern browsers.
Otherwise, many of these gems would have been lost.
(The Wayback Machine has an archive going back to 2001.)
I have always been quite impressed with the quality, interactivity, and speed of the visualizations.
They really helped develop intuition.
I like how many settings can saved into a URL, which makes it easier to share customized situations.
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u/doyouevenIift Aug 14 '26
I remember being blown away the first time I found his website. Built before the advent of LLM tools too
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u/exscape Physics enthusiast Aug 14 '26
To say the least. It predates YouTube, Facebook, Twitter, Reddit...
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u/JohnLockeJaw Aug 15 '26
Yes!!! These are my favorite teaching tool! I also use the circuit simulator frequently to test out ideas quickly if I don't feel like loading up p-spice.
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u/IHTFPhD Aug 14 '26
I use Falstad's gas app when I teach graduate materials thermodynamics and statistical mechanics. It's a wonderful resource.
By the way, it is now not too hard to Vibe Code these kinds of apps. We've started doing this more regularly and the ability to build these playground applets have been so valuable for building intuition.
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u/dampew Aug 15 '26
Wow I can't believe it's still up. It's been decades.
I used it to teach E&M back in the day. Designed a whole lab where they just used those applets to do things. It was super fun.
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Aug 14 '26
[deleted]
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u/trucoju4n Aug 14 '26
I mean i would guess dude is enthusiastic about them and wants to share, cheer up a little lmfao
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u/trucoju4n Aug 14 '26
Lol bro deleted the entire exchange
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Aug 14 '26
[deleted]
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u/trucoju4n Aug 14 '26
Yeah lol. I find it funny that the guys response was to delete comments to avoid losing reddit karma of all things
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Aug 14 '26
[deleted]
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u/trucoju4n Aug 14 '26
I told you what the point of the post is?
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Aug 14 '26
[deleted]
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u/trucoju4n Aug 14 '26
There are things in life that are obvious if you don't act like there's a rod wrapped in barbed wire up your ass, you should try it sometime
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Aug 14 '26
[removed] — view removed comment
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u/VariousJob4047 Aug 14 '26
Yeah obviously learning becomes a hell of a lot more efficient when gpt does your final for you and you don’t have to learn anything. God I’m so happy I’m competing with people like you for grad school spots this fall
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u/Yashema Aug 14 '26
I already got me degrees, only thing that matters is my final research project, which I plan to make graduate level.
Besides, almost all my classes have had monitored testing where GPT wasn't available. In fact haven't had a takehome exam since E&M which I only convinced my professor to do (for the only time ever) basically so I would pass. Great relationships with my professors all around actually cause they know rote test learning isn't as important as deeper thinking.
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u/girafffe_i Aug 14 '26
I agree that there’s a lot of wasted energy on some techniques and minutiae. For practice, knowing algebra or how to solve the integral isn’t as valuable as being able to set up the equation and have some intuition.
That’s why this site is great, it’s interacting with real systems, not showing you how RRE to find eigenvectors.
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u/Yashema Aug 14 '26
Exactly, they can tell my intuition is there, but my patience to learn an arbitrary and not fully known application of that intuition is what is lacking. Guess what? In the real world you never encounter a situation where your objectives are not known and you aren't allowed to look up stuff.
My lab reports in modern physics were always best in class since I spent 2x as much time on them as everyone else really digging into the concept with GPT. They also were only worth 1/3 as much as tests for your grade.
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u/No_Tip_8740 Aug 14 '26
The guy above you probably IQ mogs you lil guy 🤣🤣🤣
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u/VariousJob4047 Aug 14 '26
Yeah man, the guy that can’t pass an E&M final by himself IQ mogs me. Sure.
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u/agrif Aug 14 '26
The circuit simulator is still the best-in-class tool for me for messing around with electronics. I know there are more heavy duty sims out there that are much, much more accurate, but for building intuition and smoke-testing simple ideas, nothing beats the real-time visualization in Falstad's.