An exploration of physics and the facts that build it.
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Is Bitcoin Currently Experiencing a Selfish Miner Attack?

Probably not. All right, now that you know my conclusion, let’s see how to get there with data. First, some background. Let me give very quick overview of Bitcoin in this context. (There are many comprehensive overviews elsewhere.) Bitcoin is an ongoing ledger of transactions of along the lines of “This guy had 5 Bitcoins, and he sent 2 of them to that...

Sun Jan 12, 2014 20:18
How often does the sun emit 1 TeV photons?

I had an interesting question posed to me recently: how frequently does the sun emit photons with an energy greater than 1 TeV? All of you know about the experiments going on at the LHC, where particles are accelerated to an energy which is equivalent to an electron being accelerated through a potential difference of trillions of volts (which is what...

Sat Nov 30, 2013 12:06
Everything in Pi… maybe.

George Takei posted the following thing to Facebook recently: It got reposted by a bunch of people and provoked a tremendous amount of discussion (for a math topic, anyway), much of which was somewhere in the continuum between merely wrong and psychedelically incoherent. It’s not a new subject – a version of the image got discussed on Stack Exchange...

Fri Apr 12, 2013 17:09
Why are clouds white?

Why is the sky blue? It’s a classic question – probably the classic question of the genre of explanatory popular physics. The famous short version of the answer is that Rayleigh scattering by air molecules affects short-waveength light more than long-wavelength light, and so blue light tends to get scattered in random directions to create the diffuse...

Mon Apr 1, 2013 17:53
Light from a Hairbrush

Question from a reader: Pick up a comb, rub it with your hair and you have got some electric charge. Now shake it and you are generating an electromagnetic wave. Am I right? Yes indeed. So why don’t we see light emitted when we brush our hair? Let’s run some numbers. If you wiggle around an electric point charge, electromagnetic radiation is emitted....

Fri Mar 15, 2013 18:20
Quick, hit the brakes!

A reader emailed me a fun question from a physics exam he took, along these lines: A car driver going at some speed v suddenly finds a wide wall at a distance r. Should he apply brakes or turn the car in a circle of radius r to avoid hitting the wall? My first thought was that surely the question wasn’t doable without more information, but it turns...

Wed Feb 27, 2013 18:47

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