Steve Trettel
@stevejtrettel
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Math Prof: Geometry, Topology and Illustration @usfca. Minnesotan, from the occupied lands of the Dakota people.
San Francisco, CA
Joined August 2012
Its finally official and my job search is over - I could not be more excited to be joining the University of San Francisco this coming fall in a tenure-track roll!.
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RT @graveolens: /Danceability of twisted virtual knots.Sol Addison, Nancy Scherich, Lila Snodgrass/. .
arxiv.org
Over the years, several Bridges papers have delved into the concept of danceability of a knot diagram. Inspired by dancing on non-orientable surfaces, in this paper, we expand danceability to...
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RT @mathGTb: Brittenham, Hermiller: Unknotting number is not additive under connected sum h….
arxiv.org
We give the first examples of a pair of knots $K_1$,$K_2$ in the 3-sphere for which their unknotting numbers satisfy $u(K_1\#K_2)
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RT @RobFathauerArt: Some photos from the exhibition that opened at the Museum of Mathematics Thursday, on 5th Ave in NYC. The other artists….
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RT @neozhaoliang: For those who are interested in how this animation is made, here is a Python + GLSL reproduce:.ht….
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RT @GovTimWalz: No matter who you are or who you love, you are welcome here. Happy Pride Month, Minnesota!
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RT @msmathcomp: The German Mathematical Society, @dmv_mathematik, opened submissions to their "Media Prize" for outstanding presentations o….
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Ugh! Typo alert in post 3, when the film and Dino are *colinear* with the black hole, not “cloned”! 😣.
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And then, after tracing several billion more rays, the resulting film looks like this 🤯🤩
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Running the simulation for several million photons, you can start to see the Dino resolving on the simulated film
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Here’s the view of the Dino from each of several thousand pixels: can you start to see its shape if you hold the phone far away? 🤓
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Heuristically , we expect a "blurry" image to form: a bright outline of the dino on the area exposed to einstein rings, and a decaying green 'halo' as the lensed dino moves outside the black holes line of sight. Here’s the light contributing to several hundred pixels
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When a piece of the film is not lined up directly with a portion of the dinosaur, it does not form a ring, and so contributes less overall light
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The intuition: when a piece of the film is cloned with the dinosaur and black hole, from that point on the films perspective the dinosaur will be distorted into an einstein ring, taking up a large portion of the field of view, imparting that pixel with extra green light
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A crazy idea - but I had to know, so I built a little simulator! Here's the setup: a little toy dinosaur and a conical spotlight, then a black hole, then a simulated piece of film (that will record when a simulated photon hits it, and accumulate them)
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Summers here - time to catch up sharing some of what I’ve been up to! First up - *gravitational photography* - using (simulated) black holes instead of lenses to focus an image onto a screen. Can you see the ghostly dinosaur? 1/n
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RT @keenanisalive: If you're a prospective PhD student interested in geometry, topology, and applications in geometric/visual computing, ch….
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#NewProfilePic: actually same pic but AI cartoon-ification sure has improved in the last 2 years 😁
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Unsurprised but amused that the “we are doing tarrifs to bring manufacturing to America” people are now exempting those products when assembled elsewhere (but still tarrifing the components, if we imported to build here). 😵💫.
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