Relativity for Kids

there's no link.
A friend sent me this email regarding her son:

Hi there. I need help with a question that Max just asked.

If someone is traveling at the speed of light, could they see themselves in a mirror?

This was my reply. I'll point her here if you'd like to chime in with supplements.

Well, that's very similar to the question that Einstein asked -- what happens if you run as fast as a beam of light -- and to answer it, you have to change the way you think about the world. Fundamentally.

The speed of light isn't a speed you can go. It's just the end of what 'fast' is. A fuel tank has a gauge, it reads 'empty' to 'full.' For speed, 'Empty' is analogous to not moving. 'Full' is the speed of light. It doesn't make sense to talk about speeds past that any more than it would make sense to add gas to a full tank.

So, OK. The speed of light is the end of acceleration. You can't go the speed of light, because if you could, you could just juice it a little more and go faster, which wouldn't make any sense. You can only approach the speed of light. Acceleration gets harder and harder the closer you get.

Now, what does speed mean? If I leave my house, and trot along at 3 MPH, I'm moving at 3 MPH relative to my house. But, what about when I can't see my house? How would I know how fast I was moving? There's a bunch of other stuff in my neighborhood that moves at the same speed as my house, and I can choose one of those things to measure myself against. But, I have to choose something. And, as I measure it, I'm really measuring how fast that thing is moving relative to me. I really never move, from my perspective, right? We're all the center of our worlds, just like it feels.

Those are two points.
(1) I don't ever actually move. Things move relative to me.
(2) Those things never go as fast as the speed of light.

I forget how old Max is. Ah... you got married in, what, 1993? So, he was born in 1994? He's 14? Einstein was 16, you know. Anyway, I'm not going to muddy the waters with quantum dynamics. I'm not super sure I resolve them off the top of my head, anyway -- I think there's some outstanding paradox; I believe there was some news in recent years, but I didn't follow.

Clearly, there are some implications for time, here, and resolving that has some implication for linear distance. But, I'll let Max work those out for himself.

Inauguration

Liberals

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Hee, hee.

Now added to the pantheon of "liberal" dogma is the shrill, ideological belief that high government officials must abide by our laws and should be treated like any other citizen when they break them. To believe that now makes you not just a "liberal," but worse: a "liberal score-settler." Apparently, one can attain the glorious status of being a moderate, a centrist, a high-minded independent only if one believes that high political officials (and our most powerful industries, such as the telecoms) should be able to break numerous laws (i.e.: commit felonies), openly admit that they've done so, and then be immunized from all consequences. That's how our ideological spectrum is now defined.

You tell 'em, Glenn.

Patent and Trademark Giveaway cartoons

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If you're still angry about the Boston Garden being renamed the 'Failed Bank Auditorium for Sports,' or whatever it is, this is a pretty funny series of cartoons. Don't miss Frito Lay the Verizon Middletown City Council meeting.

Two Words: Forest Fire

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Now, the very fact that this crisis is largely of our own making means that it's not beyond our ability to solve.

That's not what that means. If a crisis is of your own making, you have to change your patterns of behavior and responses to events -- that's hard. Not to be not hopeful, but I'm not tracking the rhetoric.

Foreskin

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So, I was just coming to this blog to post this apology; I typed 'Male' into Firefox's address bar and hit 'enter.' I got the Google search for 'male', which included this fascinating page on foreskins, which I know almost nothing about. I'm sure I've seen them, but I've never noted one outside the movies.

The foreskin performs several important functions. Most of these functions center on making sex more enjoyable, not only for just one, but for both partners.

Protection
Makes sex feel better
Lubricates during intercourse
Lubricates during masturbation
Reduces the drop insensitivity through age
Allows the erection to grow
Increases sensitivity slowing intercourse

They sound like great things.

Manhattan Exceptionalism draws to a close

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In Manhattan, the inventory of apartments listed for sale rose almost 40 percent from a year ago to 9,081 units. Apartments sat on the market for an average 159 days before selling in the fourth quarter, up 21 percent from a year earlier, Miller Samuel and Prudential said.
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Almost no new contracts were signed on condominiums in the quarter, said Miller.
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New Yorkers paid less for smaller apartments. The median price of a studio fell 8.5 percent to $420,000, according to Miller Samuel. One bedroom prices were $715,000, down 4.5 percent.

Prices rose 9.1 percent for two-bedroom apartments to a median of $1.62 million. Three bedroom apartments slid 6.4 percent to $4.05 million, Miller Samuel said.
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In the luxury market, defined as the top 10 percent of sales by price, the median fell to $4.13 million in the fourth quarter from $4.3 million in the fourth quarter of 2007. Inventory rose 26 percent to 1,730 apartments. Luxury units stayed on the market 169 days, 52 more days than the same period a year earlier.
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“Foreign investors are having a real tough time getting mortgage money, and a lot of those young affluent buyers aren’t so affluent any more,” [Pam] Liebman, [chief executive officer of Corcoran in Manhattan] said.

Still, if you can borrow at 5.1 % ... say prices deflate 2%/year over the next two years before 20% inflation hangs around for another eight years. Prices will have gone up (.98)^2(1.2)^8 - 1 = 313%. If the real value of your house is half what it is now, the nominal value will still have more than doubled, or gone up 7.2 % a year. So, you're borrowing at 5.1% to get a 7.2% return. That's like free money.

Sticking with our assumption that the next two years will have 2 % deflation and ten years from now your house will have half its real value, you'd break even if years three through ten were at 16.6 %. If you expand the time horizon to 15 years (and your house will probably hang steady at half it's Q109 real value), you could let years three through fifteen be at 12 % inflation. You've got to agree that a twelve per cent inflation rate from 2011 to 2024 is a pretty conservative estimate. Paying off a 5.1% fixed interest loan on a depreciating asset will feel airy and light!

iPod Platelet

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To review, I started accumulating platelet donation points in the interest of getting an iPod Nano 3G at 2600 points.
I bought an iPod Nano.
I had the NYPD write my driver's license number on it with indelible ultraviolet ink.
I went to a Yankees game and lost the iPod. The police said that to even file the thing as missing, I'd have to go back to the Bronx. How could I have ever thought going to a baseball game was going to work out for me?
I've reached 2200 points in platelet donations. On January 11th, I'll reach 2550 points (100 pts + 100 pts for Sunday, 100 pts for a triple and 50 points for a critical period.) So close.
So... they don't offer the iPod 3G any more. The 4G looks suckier, doesn't power by firewire, and won't fit the various 3G paraphernalia* I own. The big problem with it is that it's 4044 points -- another 15 100 point donations (or 5 300 point donations) after Sunday.
Well, OK. I can accept that I get punished for cheating. But, I'm going back to Maya-land at the end of March. My last trip to Cobá kept me from donating for 6 months, as it's malarial, and not donating for 6 months invalidates all of my points.
Apparently, I'm in a race against the clock.

* -- A win for Firefox's spell checker. Apparently, I've been incorrectly dropping the second 'r' from that word my whole life.