Viewing profile — ultrafilter

Your charge-based g-meter would also measure zero acceleration in free fall. https://en.wikipedia.org/wiki/Paradox_of_radiation_of_charge...

Near the end, the author claims that if a,b,c form a basis of R3, then the cross products a x b, b x c, and c x a are orthogonal. This is false. E.g., a=(1,1,0), b=(0,1,1), c=(1,0,…

If I have a keyboard, then for a relatively small dataset, such as my saved passwords, I prefer a text file over any database. Lookup workflow: decrypt file (with, say, gpg), find …

Set theorists have located the "end" for all practical and most impractical purposes. Let M be the minimal countable transitive model of ZFC. Declare a real to be useful if and onl…

If you're giving the book away, why not release the source (LaTeX, Word, whatever) in addition to your favorite subset of {PDF,EPUB,...}? Then readers who want a different format h…

The author's more recent work is here: http://arc.cecs.pdx.edu/publications

You're right. I should have written "halts last among its peers" or similar.

Every formal axiom system, whether about sets or anything else, can only prove that N of Busy Beavers halt, for some (not-too-large in practice) finite number N. If you just want t…

Nice overall; my only complaint is that you raised the question "Are LTC log returns normally distributed?" but only gave an uninterpreted graphical comparsion. I was hoping for a …

I put a copy of putty at a short but private url at my own domain so that I can get it over https.

Indeed, the source code only considers tax brackets, the personal exemption, and the standard deduction. I've read of an increase of $650 in the per-child tax credit combined with …

Yes. Perhaps the voting currency should be hours, not dollars. Make the first vote free. But N-1 more votes costs you N^2-1 hours from your "registered community service" account m…

The Carnot cycle is a poor model for steam turbine electric power plants. Rankine cycle efficiency of ~40% is the more relevant theoretical upper limit. https://en.wikipedia.org/wi…

In the real world, Hamkins' program would search forever, never outputting anything. In the context of a "nonstandard" version of the line of natural numbers, "finite" no longer me…

The article has a link in a sidebar: https://arxiv.org/abs/1608.01008v2

I think your watch is slow and you think mine is slow in the following sense. For each of many events, I record their time t and position x while you, moving relative to me at cons…

In contrast (but not contradiction) with your experience, as an MIT undergraduate math major applying for PhD programs, my advisor warned me that the math dept. doesn't admit their…

Theorems 1 and 3 are finitary and easier to physically interpret. As for Theorem 2, "With probably p a random foo has property bar" intends no interpretation of "random foo"; it me…

There's no relation to his incompleteness theorems. Gödel proved that every universe V of sets that satisfies the (ZFC) axioms has a subuniverse L that satisfies both the axioms an…

The man's escape strategy described in the post was discovered in 1952 by Besicovitch. It has a kind of discontinuity because, quoting the post, "There are 2 perpendicular paths. C…