There's been a bit of a controversy recently regarding Euclideon's "Unlimited Details" 3D rendering technology: The Word of Notch, written by Markus Persson, the author of Minecraft, published a post titled "It's a scam!", suggesting essentially that it's just a sparse voxel octree, and that the company is over-hyping well known techniques to get some funding. … Continue reading In defense of Euclideon’s Unlimited Details claims

## P versus NP

A researcher from HP Labs named Vinay Deolalikar announced a new proof that complexity classes P and NP are different. The paper made it to the Slashdot front-page (more on this below). What constitutes a "proof"? This is far from being the first claimed proof. There are about as many proofs that P is the same … Continue reading P versus NP

## Really bad math in a sci-fi book…

I have just been reading Alien Embassy by Ian Watson (in the French translation published by Presses Pocket). This is a somewhat esoteric book, and I can't say that I'm really fond of that genre. But it is an interesting story, it's well written, and I enjoyed it. Howewer, something really puzzled me, and it … Continue reading Really bad math in a sci-fi book…

## The number you can’t compute…

One of my respected colleagues at Hewlett-Packard is a guy named Patrick Demichel. He's one of the "titans", having held various world records on the number of digits of π and things like that. But a couple of weeks ago, he talked to me about something really intriguing. During a conference on high-performance computing, he … Continue reading The number you can’t compute…

## Are real numbers real?

In the past months, I have pointed out a few times that real numbers have no reason to exist in physics, if only because our measurement instruments don't have an infinite precision and range. In general, this point, which I believe should make any physicist nervous, does not get much traction. Maybe most people simply … Continue reading Are real numbers real?

## Embedding mathematical formulas in a blog

The folks at Noncommutative geometry have given me a useful hint to embed mathematical formulas directly in a blog or web page: the use of TeXify. Here is an illustration with the collapse of the wave function written using the formalism of the theory of incomplete measurements: . There are just three issues with that … Continue reading Embedding mathematical formulas in a blog

## 3D simulation of the 9/11 attacks

A finite elements simulation of the 9/11 World Trade Center attacks was carried out and visualized using 3D rendering.