Bartosz Milewski

I used to watch his YouTube videos, but I got gradually disillusioned by his ideology. He's actually motivating his philosophy of mathematics by his religious beliefs. So when he says a number "exists" he means it was created by God.

2025-03-21 08:36:51 UTC

- reply

I have 34k followers and I'm almost exclusively posting about politics. I have a feeling that Musk (if he paid any attention) would rather have me quit. It makes no difference that I'm doing it from France. Living in the US was just too depressing.

2025-03-20 18:17:57 UTC

- reply

I'm worried about people reacting to Trump excesses by withdrawing to safe environments--ceding territory to the enemy. It makes sense to boycott Tesla, but it's counterproductive to withdraw from Twitter, which is a huge public forum. As long as Musk is not blocking critical voices, we can engage and be heard by lots of people. Our voices have to be louder, not quieter. Every negative action by Trump, Vance, or Musk must be met with strong reaction.

2025-03-16 20:27:05 UTC

- reply

Kenny G and David Sanborn created the genre of music that I call jazzak (a portmaneau of jazz and muzak)

2025-03-07 09:19:25 UTC

- reply

Yes, I've heard about the Steele's dossier. It was also investigated in the Mueller report. I don't think it's a very reliable source.
Also, I'm not sure if Trump can be compromised. Even if the golden shower tapes were released tomorrow, he would say, "That's just what guys do in Russian hotels" and the MAGA people would heartily applaude.
I'm more inclined to speculate that Moscow offered him power and money. And they are delivering on it.

2025-02-24 09:22:27 UTC

- reply

What Europe should, and hopefully will do soon, is to confiscate frozen Russian assets worth 210 billion euro and give it to Ukraine. https://www.euronews.com/my-europe/2025/02/20/tusk-calls-on-eu-to-confiscate-russias-frozen-assets-to-provide-ukraine-with-financial-ass

2025-02-22 16:25:54 UTC

- reply

No, a functor is like a duck confit: it preserves the structure of the bird, but infuses it with a new meaning.

2025-02-09 19:56:16 UTC

- reply

I have a museum pass to the Louvre, so I had the opportunity to appreciate the Mona Lisa without the usual crowds. There is something, je ne sais quoi, about this painting that I'm sure most of the selfie people miss.
https://media.mathstodon.xyz/media_attachments/files/113/975/669/846/227/252/original/81e75fa7547a8f68.jpeg

2025-01-23 09:06:32 UTC

- reply

The organic quality of this image is reminiscent of blastulation. https://en.wikipedia.org/wiki/Blastulation

2025-01-18 23:20:43 UTC

- reply

"By the way, the argument about whether viruses and the even simpler viroids are 'life' seems silly to me."
Next thing people will start arguing whether machines can have consciousness. Oh, wait...

2024-12-30 12:38:33 UTC

- reply

Physicist can forge ahead and get away with inconsistent mathematics if they can offer procedures for calculating things that can be experimentally verified. Renormalization is a cludge, but it works. However, this kind of approach is no longer acceptable if experimental verification is impossible. Then it's just a hallucination.

2024-11-30 00:25:59 UTC

- reply

That's what I mean:
"an outside observer will never see an object actually fall into a black hole. The object instead will appear to freeze at the event horizon."
https://www.astronomy.com/science/ask-astro-frozen-stars/

2024-11-29 19:33:43 UTC

- reply

You keep saying that my questions make no sense, but all I'm asking is what Bob sees with his own eyes. Surely his retinas are registering something that can be objectively described. I thought it was common knowledge that, when he's still far away, he sees the spaceships bunching up and getting thinner and redder in front of the horizon. In fact he can see the horizon as the bunching-up point. He can't see the ships crossing the horizon. Or am I completely off?

2024-11-29 11:30:28 UTC

- reply

The reason I'm struggling is that I'm desperately trying to reconcile the large and the small scales. After all there has to be a continuous transition between them in the course of a free fall. At large scale, the observer sees the ships in front of him piling up at the horizon. Eventually, the observer gets close to the horizon. What does he see then? Do the piled up ships start suddenly slipping through the horizon? I seem to have exhausted the ways of explaining this problem away.

2024-11-28 20:02:05 UTC

- reply

I'm not trying to be difficult. The reason I'm jumping between scales is that I feel there has to be some kind of scale invariance near the horizon. You scale the distance to the horizon and the time to the horizon and the physics should be (approximately) the same. I may be wrong, but that's my gut feeling.

2024-11-28 10:58:06 UTC

- reply

I'm trying to reconcile our points of view, and the only way we can both be right if we are using different definitions. In particular, what does it mean to _see_ something and tell how far it is from us. Normally, we'd use binocular vision and triangulate. I'm not sure how that would work near the horizon. We could also use the radar, but that's not the same as looking. So here is the definition that supports my point of view:
The ship in front of me keeps transmitting its coordinates (faster and faster and using shorter and shorter wavelengths to adjust for the redshift I'm perceiving). With this definition, I will "see it" stalling in front of the horizon. If there are multiple ships, I will "see" them squeezed in front of the horizon. Do you agree?

2024-11-28 00:46:19 UTC

- reply

Frankly, I don't know. Is the answer obvious?

2024-11-27 22:52:04 UTC

- reply

When you're learning special relativity, things like relativistic contraction are explained by switching between inertial frames. The stationary observer watches the moving observer bouncing rays of light back and forth to measure distances. In the stationary frame, the moving train car is shorter. This is how you measure things. It's not the same as how you _see_ things, which is what I was talking about before.

2024-11-27 21:13:49 UTC

- reply

The standard way to measure distance is to consider a round trip of a ray of light. Since your nose is receding, most of the trip is spent catching up with your nose. But what you _see_ is the light emitted by your nose, and your eye is running towards it, so it seems very close.

2024-11-27 18:16:40 UTC

- reply

Consider what it would look like from the point of view of a bacterium in your eye. Your nose becomes the spaceship that is very close to the horizon. You see it flatten against it, as you're approaching it.
In fact, even people far away from the horizon see their noses flattened and red-shifted, only the effect is so minute that it's undetectable. The solutions to Einstein equations are continuous, so the effects of gravity fall off with distance but never disappear completely.

2024-11-25 23:26:50 UTC

- reply

@npub1nf4…nqe4 @npub12cu…d38p
I think I learned a lot through this discussion. But I'm not done yet, so bear with me.
Suppose every ship lights up a beacon when they cross the horizon. I will see all the beacons light up at once the moment I cross the horizon. This is consistent with the perception that the horizon has been moving towards me with the speed of light ever since the first ship hit it. But has it? I only started my free fall recently. Before then I was hovering at a constant distance using my engines.
Even worse, imagine that the line of starships is 100 light years long and it takes me 200 years to reach the black hole. In the meanwhile the first ship can't hit the horizon because it has to wait for me. Do I see it slow down, or do I see it go through the black hole?

2024-11-24 16:58:29 UTC

- reply

I think we have to assume that "passing the horizon" is a subjective thing. Suppose they both can tell when they are passing their horizon. Alice blinks when she does. When Bob sees her blinking, he is passing his horizon. He infers that Alice's horizon is different from his.
I see one problem with this, though. Theoretically, it should be possible to put a fence very close to the horizon--a swarm of near-light-speed particles orbiting it. From Bob's perspective, he'd be hitting it while watching Alice hitting it at the same time.

2024-11-24 14:57:50 UTC

- reply

Assume that they are both falling one after another along the same straight line towards the singularity (they maneuvered themselves into this trajectory when still at some distance from the black hole). Bob sees Alice always directly in front of him. So unless he bumps into her crossing the horizon, his perception of where the horizon is must be different from hers.

2024-11-24 14:08:54 UTC

- reply

The scenario I'm interested it is of two astronauts Alice and Bob jumping off the ship. Bob can't see Alice crossing the horizon before he himself crosses it. So either he sees Alice splashed on the horizon, or the horizon recedes in front of him. I can't make sense of it.

2024-11-24 13:43:03 UTC

- reply

Yes, it takes practice to read Penrose diagrams. The difficulty for me is to figure out what the world looks like from the point of view on a given observer. I think the "dust trail" in @npub12cu…d38p visualization comes closest to the situation I'm interested in. I think, for a very large black hole, the dust lines would be practically vertical. Is that right?

2024-11-22 09:54:37 UTC

- reply

So you see my confusion: If the approaching horizon looks like a black wall, you shouldn't be able to see your hand that has just crossed it.

2024-11-21 19:41:14 UTC

- reply

If my hand doesn't disappear, it means I can see things in front of me, including the singularity? What does the singularity look like?

2024-11-21 18:23:20 UTC

- reply

"We could be falling through the event horizon of a truly enormous black hole right now."
I've been always puzzled by this. Surely you'd see the horizon as a black surface coming at you, since no light can escape the black hole. And once your legs get past the horizon, you'd lose the feeling in them forever. Although the math inside a black hole gets really crazy, so I don't know how much I can trust my intuitions.