Thursday, August 25, 2016

How much damage would a space probe take flying through the interstellar medium at v=0.2c? (See also this.)

Bottom line: I am seriously entertaining the possibility that I will live to see digital images transmitted from another planetary system.

Wednesday, August 24, 2016

If Saudi Arabia and Iran are fighting a proxy war in Yemen, why is the US taking sides?

Tuesday, August 23, 2016

Saturday, August 20, 2016

Friday, July 22, 2016

At this date, I think it good to revisit my earlier comparison between a million and one. Large numbers are sometimes difficult to reason about, so perhaps using a log scale would help. Let's see... Yep, six strictly exceeds zero.

I am reminded of Peter Thiel's 2009 counsel to escape politics (though he clearly hasn't escaped yet). He sees technology as liberty's only hope. I wish the techno-libertarians well. Why do I say that, when I have become much less individualist over the years? I am simply concerned for the freedoms of my religious community. The Democratic presidential nominee promises nothing but setbacks on that front, and the Republican nominee's promises on that front are worthless because (1) he is incompetent and foolish in a million ways and (2) his harshness invites a huge backlash to come after him. I have reservations about the libertarian nominee, but I have yet to think of a better protest vote.

Update: See also this and this.

At this date, I think it good to revisit my earlier comparison between a million and one. Large numbers are sometimes difficult to reason about, so perhaps using a log scale would help. Let's see... Yep, six strictly exceeds zero.

I am reminded of Peter Thiel's 2009 counsel to escape politics (though he clearly hasn't escaped yet). He sees technology as liberty's only hope. I wish the techno-libertarians well. Why do I say that, when I have become much less individualist over the years? I am simply concerned for the freedoms of my religious community. The Democratic presidential nominee promises nothing but setbacks on that front, and the Republican nominee's promises on that front are worthless because (1) he is incompetent and foolish in a million ways and (2) his harshness invites a huge backlash to come after him. I have reservations about the libertarian nominee, but I have yet to think of a better protest vote.

Wednesday, June 08, 2016

Don't carry much cash on a road trip, and now don't carry prepaid debit cards either. The bandits have new technology.

Wednesday, June 01, 2016

This is the easiest yet still significant mathematics paper I've read in a long time. (See also Quanta Magazine's coverage.)

Saturday, May 07, 2016

Given my apparent choices in November, I can think of a million reasons not to vote for him who shall not be named, and one reason to vote for him.

Wednesday, April 13, 2016

An 8-dimensional and then a 24-dimensional analog of Kepler's sphere-packing conjecture, widely believed to be true (and actually used for error-correcting codes), were proven true last month, with the major breakthrough due to Maryna Viazovska. (Hales proved the original conjecture in the 1990s.) I noticed that the paper on dimension 24 has Abhinav Kumar as a coauthor. On my dorm floor way back when, Abhinav was a "greater math god" and I was a "lesser math god."

P.S. Why does that paper talk of "+1 eigenfunctions"? What's wrong with "fixed point"?

Thursday, April 07, 2016

In the asymptotically safe gravity proposal, quantum gravity is weaker at high energies. In this proposal, gravity is both weaker and less quantum (meaning the effective Planck length (but not the Planck mass) is smaller) at high energies.

Imagine that "everybody wins" mathematically, i.e., it is proven there are elegant mathematical models consistent with observation and unifying all of fundamental physics, including an asymptotically safe gravity model, a string theory model, loop quantum gravity model, maybe other models I don't want to take the time to mention, and maybe even an "unquantizing" model like in the link. Which theory will win the parsimony contest? Since parsimony is not the same as mathematical elegance or beauty, I'm not confident that the most parsimonious theory will also become most popular.

Friday, March 18, 2016

Positive question: was Rubio the Condorcet winner of the Republican Presidential primary? I don't have the data to say, but it seems at least plausible.

Normative question: Should not the Condorcet winner (if one exists) be the actual winner? (This isn't special pleading; I didn't vote for Rubio in Texas.) Why not let voters somehow rank candidates on their ballots?

Friday, February 26, 2016

"Regulation for thee, but not for me." Democrats usually favor and Republicans usually oppose government regulation of business. What about government regulation of government? What about regulation of organizations receiving government funding? Many critiques of regulating business apply equally well to regulating governments and those they fund: bottlenecks caused by slow approval processes, uniform rules that don't make sense for every organization, and high compliance costs (e.g., man-hours spent learning the regulations and documenting compliance) that overly burden (and in some cases even prevent or destroy) small organizations and their innovative initiatives. "Small organizations" includes small departments with larger organizations.

I see these problems all too often in my job. I also recently saw how even the student organizations at my university are over-regulated. This blog post was provoked by Section 51.9361 of Subchapter Z of Chapter 51 of Subtitle A of Title 3 of the Texas Education Code.

For another anecdote, I've done a bit of mentoring of future middle-school and high-school math teachers. Once they start their training at the local public schools, they are unanimously dismayed by the emphasis they see given to preparing the students for state-mandated exams. (Home schooling in Texas, on the other hand, is hardly regulated at all. I highly recommend it.)

I have an abstract, general desire for smaller governments, but I expect defense, law enforcement, infrastructure, education, and research to be extensively funded by governments (but perhaps not directly provided by governments) from now until the end of the world. Therefore, quoting Robin Hanson,

This view suggests that being pro- or anti-regulation isn’t the same as being pro- or anti-government, and it suggests a possible left-right deal: reduce regulation in both private and public sectors. Have more trust in private competition to deal with the problems we leave to the private sphere, and in smart well-trained civil servants to deal with the problems we leave to the public sphere. And have less trust in lawyers, judges and rule-specialists of all sorts to fix our problems with more rules.

Monday, February 15, 2016

In defense of the cosmological constant.

On the other hand, cosmic inflation I still consider quite mysterious.

Friday, February 12, 2016

Thursday, February 11, 2016

Sunday, February 07, 2016

An ancient Cappadocian church, frescoes included, has recently been uncovered. I've read conflicting reports about how ancient.

Wednesday, December 09, 2015

Laredo is just barely south enough for the very variable Eta Carinae to peak above the horizon. Also, the temperature reached 300K (80F) today (Dec. 9) and the NOAA forecasts we will reach 305K (89F) tomorrow.

Monday, December 07, 2015

Do I dare hope there exists a market monetarist presidential candidate?

Wednesday, November 18, 2015

The space doctor's big idea, a New Yorker article by Randall Munroe.

Saturday, October 31, 2015

I find this hilarious. I wonder what jokes spelunkers particularly enjoy.

Friday, October 23, 2015

Saturday, September 12, 2015

Where I live, the Central Standard Time of solar noon varies from about 12:20 to 12:50 over a year. (My watch is currently one hour ahead of CST because of DST.) About three quarters of the variance is explained by axial tilt; approximately all of the rest of the variance is explained by orbital eccentricity.

Monday, July 20, 2015

Historic astronomical measurements, continued: solar deflection of starlight.

Friday, July 17, 2015

Friday, May 15, 2015

Saturday, May 09, 2015

Thursday, March 26, 2015

An interesting application of the anthropic principle to inflationary cosmology. I'm impressed with the successful "predictions" of the cosmological constant. Note that the "multiverse" involved here is not the "many worlds" of the Everett interpretation of quantum mechanics nor a space of theories like the string theory landscape. It's just a universe with different regions---"bubbles"---expanding differently.

It would nice to explain why the cosmological constant is what it is. Yet, no one tries to explain why the earth's orbital radius is what is beyond saying that it needs to be roughly what it is to support life. Where does this analogy break down? We have observed many other, apparently lifeless solar systems; it is possible but improbable that we might someday find indirect evidence for a bubble beyond our own in the cosmic microwave background.

Wednesday, March 25, 2015

Until I read this recently, I didn't realize that the Bohmian interpretation of quantum mechanics had been successfully extended to special relativity and field theory. As even staunch proponents of the Everett "many worlds" interpretation admit, the Bohmian and Everett interpretations are observationally equivalent. So, which is preferable, a theory of one universe with non-locally interacting particles and a locally evolving wave function, or a theory of a multiverse with just a locally evolving wave function? I'm now strongly in favor of the Bohmian option.

Tuesday, March 24, 2015

Loosely related to my previous post, consider the following evaluation of Vancouver's trend of wealthy foreigners buying homes in the city.
[W]hen highly educated folks making six figures still can’t afford to live in your city (and it takes over an hour’s commute to get to downtown from slightly more affordable areas), you simply don’t have the conditions to grow a knowledge economy....

Entire downtown neighbourhoods and chunks of the west side are growingly becoming ghost towns as permanent residents are replaced with investors who don’t occupy their units....

A massive capital injection from abroad makes Vancouverites feel wealthy, while the city is in no real terms wealthier. Talented people continue to leave and with them the future of our city.

Monday, March 23, 2015

Regarding (presumably pie-in-the-sky) discussions of radical tax reform, I find it helpful to focus on real resources instead of dollars.

For example, imagine a radical 100% tax on all personal wealth over $1M that is not charitably donated. Food is cheap, millions of people in the world are hungry, and there's a lot concentrated personal wealth we could throw at the problem. There exist Bill Gates, several other billionaires, and many millionaires. Yet, if all of Gates' wealth is redirected toward immediately feeding the hungry, where do all the bags of grain come from? The Gates mansion does not have that much food in it. The bags of grain come from a combination of many people and animals eating less grain and of farmers producing more grain (and of more people working on farms instead of elsewhere, and of more raw materials being used to build farm equipment, fertilizer, pesticides, and the like, instead of other things, and of more fuel, water, and electricity being used by farms, and...)

Generally speaking, taxes do not take away real resources from wealthy people, except to the extent that it reduces wealthy people's consumption of goods and services. What matters is consumption. Moreover, personal wealth taxes can be evaded by creating a corporation structured so that you tightly control it and "investing" your personal wealth in this corporation. If the government also heavily taxes corporate wealth, then (along with many other crazy changes) almost everything will end owned by "non-profits" that pay their executives fat salaries and "re-invest" most of their remaining net income in things like comfort, prestige, and power. Exhibit A is all the money universities and hospitals pour into their campus buildings and grounds.

As folks like Scott Sumner keep saying, let us tax consumption alone. Replacing all income taxes with a value-added tax (VAT) does this. Less radically (for the US), instead of taxing personal and corporate income as we do now, the Internal Revenue Service could tax personal income minus personal savings. Your capital gains, dividends, and interest income should not be taxed, but your negative savings, i.e., net withdrawals from their savings/brokerage/etc accounts should be taxed.

Morally speaking, if a rich man lives a modest lifestyle, why should he be more than modestly taxed? How is his net worth, his labor income, or his capital income morally relevant? If someday the rich man exercises his option to live lavishly, only then tax him lavishly.

From another angle, why tax my dividends at one rate and my wages at another? Tax $1K income saved at 0%, regardless of where it come from. Tax a person's Nth $1K of annual consumption spending at a progressive rate r(N). Yes, there will still be tax deductions and tax credits that complicating things, but equalizing tax rates across income sources is still a nontrivial simplification.

If my personal consumption includes lavish job perks from my employer (which might be myself), then how are these taxed? The Right Way to solve this problem is stop taxing income and go pure VAT. The inferior but less radical solution is a corporate/self-employed consumption tax with complicated rules, but no more complicated than the current income tax rules for corporations and the self-employed.

The Achilles heel of taxing income minus savings is imputed rent. If I own a house and live in it, that is consumption, but it is not obvious how valuable that consumption is. In effect, I am both landlord and tenant, paying myself some unknown rent. Is the IRS going to estimate and tax every home owner's imputed rent? The "estimate" part isn't a show-stopper; it wouldn't be any more difficult than what property tax assessors already do. The howler is the "tax" part, which would effectively be a federal home property tax. Again, the Right Way is a VAT. A bit closer to political reality would be the policy of just not taxing imputed rents and maybe not taxing housing rent of any kind.