Dear Fellow Scholars, this is Two Minute Papers with Dr. Károly Zsolnai-Fehér.
Today we are going to design a crazy baseball bat, a hockey stick that’s not working well,
springs that won’t stop bouncing, and letters that can kind of stop bouncing.
And, yes, you see it correctly, this is a paper from 2017. Why? Well,
there are some good works that are timeless. This is one of them. You’ll see why in a moment.
When I read this paper, I saw that it is from professor Doug James’s group at Stanford
University, and at this point, I knew that crazy things are to be expected. Our seasoned Fellow
Scholars know that these folks do some absolutely amazing things that shouldn’t even be possible.
For instance, one of their earlier papers takes an animation and the physics data for these bubbles,
and, impossible as it might appear, synthesizes the sound of these bubbles. So,
video goes in, sound comes out.
And hold on to your papers because that’s nothing compared to their other work,
which takes not the video, but the sound that we recorded. So, the sound goes in,
that’s easy enough, and what does it do? Creates a video animation that matches these sounds.
That’s a crazy paper that works exceptionally well. We love those around here.
And, to top it off, both of these were handcrafted techniques, no machine learning is applied.
So, what about today’s paper? Today’s paper is about designing things that don’t work,
or things that work too well. What does that mean? Well, let me explain.
Here is a map that shows the physical bounciness parameter for a not too exciting
old simulation. Everything, and every part does the same. And here is the new method.
Red means bouncy, blue means stiff.
And now, on to the simulation. The old one with the fixed parameters. Not bad, but it not
too exciting either. And, here is the new one. Now that is a simulation has some personality.
So, with this, we can reimagine as if parts of things were made of rubber, and other parts
of wood or steel. Look. Here, the red color on the knob of the baseball bat means that this will be
made bouncy, while the end will be made stiff. What does this do? Well, let’s see together.
This is the reference simulation where every part has the same bounciness. And now,
let’s see that bouncy knob. There we go! With this, we can unleash our artistic vision
and get a simulation that works properly, given these crazy material parameters.
Now, let’s design a crazy hockey stick. This part of the hockey stick is very bouncy,
this part too, however, this part will be the sweet spot, at least for this experiment.
Let’s hit that puck and see how they behave.
Yes, from the red, bouncy regions, indeed, the puck rebounds a great deal. And now,
let’s see the sweet spot. Yes, it rebounds much less. Let’s see all of them side by side.
Now, creating such an algorithm is quite a challenge. Look,
it has to work on smooth geometry, built from hundreds of thousands of triangles.
And one of the key challenges is that the duration of the contacts can be… what?! Are
you seeing what I am seeing? The duration of some of these contacts is measured in the order of tens
of microseconds. And, it still works well, and it’s still accurate. That is absolutely amazing.
Now, of course, even though we can have detailed geometry made of crazy new materials,
this is not only a great tool for artists. This could also help with contact analysis,
and other cool engineering applications where we manufacture things that hit each other. Glorious.
So this is an amazing, timeless work from 2017, and I am worried that if we don’t talk about it
here on Two Minute Papers, almost no one will talk about it. And these works are so good,
people have to know! Thank you very much for watching this, and let’s spread the word together!
Thanks for watching and for your generous support, and I'll see you next time!