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Mad, Mad, Mad, Mad Scientist: Lisa Randall

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While doing research for an upcoming article on string theory (a "big idea" if we ever saw one), I ran across this interview with Lisa Randall. It contains the following wonderfully wacky three questions, in which Randall applies her brain to "branes," higher dimensions, and alternate universes. Gotta love physics:

If there are more than three dimensions out there, how does that change our picture of the universe?
What I'm studying is branes, membranelike objects in higher-dimensional space. Particles could be stuck to a three-dimensional brane, sort of like things could be stuck to the two-dimensional surface of a shower curtain in our three-dimensional space. Maybe electromagnetism spreads out only over three dimensions because it's trapped on a three-dimensional brane. It could be that everything we know is stuck on a brane, except for gravity.

Yet we very clearly see only three dimensions when we look around. Where could the other dimensions be hiding?
The old answer was that the extra dimensions were tiny: If something is sufficiently small, you just don't experience it. That's the way things stood until the 1990s, when Raman Sundrum and I realized you could have an infinite extra dimension if space-time is warped. Then with Andreas Karch, I found something even more dramatic—that we could live in a pocket of three dimensions in a higher-dimensional universe. It could be that where we are it looks as if there's only three dimensions in space, but elsewhere it looks like there's four or even more dimensions in space.

And there could be a whole other universe set up that way?
Possibly. It would be a different universe because, for example, bound orbits [like Earth's path around the sun] work only in three dimensions of space. And the other universe could have different laws of physics. For example, they could have a completely different force that we are immune to. We don't experience that force, and they don't experience, say, electromagnetism. So it could be that we're made of quarks and electrons, while they're made up of totally different stuff. It could be a completely different chemistry, different forces—except for gravity, which we believe would be shared.

Finally, for those of you who think that theoretical physicists are all nerdy old men wearing pocket protectors: check out Randall's picture after the jump, which could inspire a person who make all kinds of jokes about gravity and attraction.

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iStock // Ekaterina Minaeva
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Name the Author Based on the Character
May 23, 2017
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