You Can't Quietly Park at 0.1c - Samir Varma

Samir Varma

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You Can't Quietly Park at 0.1c<br>What the Physics Actually Says About the Alien Probe Hypothesis

Samir Varma<br>May 18, 2026

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People have been arguing about whether UAP sightings are aliens. Most of the arguments are not very good — blurry videos, appeals to authority, arguments from incredulity. But two very serious thinkers have made the case that the probability is appreciably nonzero, and their arguments are not easy to wave away.<br>(A note on terminology: I use “UAP” for what people report seeing, and “craft” only for the hypothesis I’m testing. The question is not whether people see things they cannot identify. They do. The question is whether the craft interpretation survives the physics.)<br>Tyler Cowen — the George Mason economist who runs Marginal Revolution — frames it as a conditional: if UAP sightings are alien, the most plausible model is unmanned drone probes with generalized software instructions — “seek out major power sources, send information back, run away if approached.” He treats it as a question about how advanced civilizations allocate discretionary surplus when costs are low and time horizons are infinite. He raises his own counterarguments. He honestly concedes the sightings “probably are not of alien creations.” But he puts the probability at around 10%.<br>Robin Hanson — Tyler’s George Mason colleague, whose work on prediction markets and “grabby aliens“ has made him one of the most original thinkers in the rationalist sphere — has gone much further: less than 20% probability on all UFOs being illusions, an elaborate structure involving stellar-nursery relatives, seeding, no-colonization rules, a 75-year military conspiracy. Robin’s version is bolder and more specific, which means it makes more testable predictions — exactly what you want from serious reasoning about a hard problem.<br>These aren’t cranks on Reddit. These are people whose reasoning I respect on every other topic. And their arguments made me think hard: could they be right? Could the probability really be 10%, or higher?<br>I’m a physicist — or at least, a recovering one. I have a PhD from UT Austin, where George Sudarshan was my advisor and Steven Weinberg was on my committee. When Congress, in its infinite wisdom, canceled the Superconducting Supercollider — the pork wasn’t spread widely enough; only Texas and Illinois were getting the bulk of the spending, which was the whole point of keeping costs down and using existing expertise — the writing was on the wall, and I had to find something else to do. My first job interview (and only job interview — I have never technically had a job in my life, unless you count being a graduate student) was at a hedge fund that has since become very famous. They wanted someone to write code to “clean” data. I asked why they wanted a physics PhD to do that. There was a long, awkward pause, and they said: “Well, physics is boring, and cleaning data is boring, so we figured a physics PhD would like it.” I spent the next three decades in quantitative finance instead. The physics, it turns out, was not boring. It was just waiting. (BTW, I’m back to writing physics papers again. Check them out if interested: samirvarma.com/publications. Turns out you can take the physicist out of physics but you can’t take physics out of the physicist. But I digress. Back to the original story.)<br>So I gave Tyler and Robin’s arguments the standard physicist’s treatment: what does the physics actually say?<br>And I immediately got it wrong. Twice.<br>I’m not a debunker. I’m not saying these are camera tricks, parallax artifacts, or people who don’t understand how video works. Maybe some of them are, maybe some aren’t — that’s a different argument, and other people are having it. My argument is different: even if every one of these videos shows a real physical object doing exactly what it appears to be doing, the physics of interstellar travel makes the alien-probe interpretation extraordinarily implausible. The observations can be entirely real and still not be probes. That’s the option I want to put on the table.<br>What follows is the story of how I tried to find what was wrong with Tyler and Robin’s reasoning, kept failing, started to think they might be right — and then found a calculation that, as far as I can tell, hasn’t been part of this conversation. It resolves the version of this question people usually argue about. The answer is lim(ε→0) ε — zero for all practical purposes.

My First Mistake: Speed of Light

My first instinct was the speed-of-light argument. Probes have mass. They can’t exceed c. The nearest star systems are a few light-years away; interesting targets span anywhere from single digits to hundreds of light-years. The galaxy is 100,000 light-years across. Whoever sent them would be long dead before any signal returns. Surely that settles it?<br>It doesn’t.<br>The Milky Way has hosted star formation for over 10...