Quote from: DannyHamilton on October 01, 2013, 07:05:14 PM

Quote from: pand70 on October 01, 2013, 06:43:20 PM

I would be funny if someone was taking the time to pair the possibility of a collision with facts like "winning a lottery 100 times in a row".
Not just saying something flashy but actually calculating the possibilities of both events.

It's been done. People just get tired of quoting the same stuff a few thousand times. Yes, this same question gets asked again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, and again, etc.

Here:

Quote from: molecular on November 03, 2012, 07:45:18 PM

Ok, new data, will recalc everything:

probability of getting struck by lightning in any given year: 1/280000.
probability of taking a shit at any given point in time: 1/(60*24) = 1/1440 (assuming you take a crap every day and the actual process takes 1 minute)
probability of getting struck by lightning while taking a crap in any given year: 1/(280000*1440) = 1/1.47E11 = 2.48E-9
probability of taking a crap while being in a situation where being struck by lightning can actually occur = 1/1440 = 0.25 = 1.74E-4
probability of finding a collision: 1E-65
getting hit by lightning while taking a crap for how many years in a row is equally probable as finding a collision: log(1E-65) / log(1.74E-4) = 17.3

is my math roughly correct now?

If so, I can say: "Finding a collision is about as likely as being struck by lightning while taking a crap every year for 17 years in a row".

Or if you prefer:

Quote from: http://www.schneier.com/blog/archives/2009/09/the_doghouse_cr.html

One of the consequences of the second law of thermodynamics is that a certain amount of energy is necessary to represent information. To record a single bit by changing the state of a system requires an amount of energy no less than kT, where T is the absolute temperature of the system and k is the Boltzman constant. (Stick with me; the physics lesson is almost over.)

Given that k = 1.38×10^-16 erg/°Kelvin, and that the ambient temperature of the universe is 3.2°Kelvin, an ideal computer running at 3.2°K would consume 4.4×10^-16 ergs every time it set or cleared a bit. To run a computer any colder than the cosmic background radiation would require extra energy to run a heat pump.

Now, the annual energy output of our sun is about 1.21×10⁴¹ ergs. This is enough to power about 2.7×10⁵⁶ single bit changes on our ideal computer; enough state changes to put a 187-bit counter through all its values. If we built a Dyson sphere around the sun and captured all its energy for 32 years, without any loss, we could power a computer to count up to 2¹⁹². Of course, it wouldn't have the energy left over to perform any useful calculations with this counter.

But that's just one star, and a measly one at that. A typical supernova releases something like 10⁵¹ ergs. (About a hundred times as much energy would be released in the form of neutrinos, but let them go for now.) If all of this energy could be channeled into a single orgy of computation, a 219-bit counter could be cycled through all of its states.

These numbers have nothing to do with the technology of the devices; they are the maximums that thermodynamics will allow. And they strongly imply that brute-force attacks against 256-bit keys will be infeasible until computers are built from something other than matter and occupy something other than space.

Both very good ones. I wonder if there's a market for a calender with daily "generating the same Bitcoin address twice is as likely as ______" ...