What are the chances of finding a hard drive containing about 100 billion yen worth of Bitcoin that was accidentally thrown away in a waste disposal site?
A man who mined about 8,000 BTC (about 97.9 billion yen) immediately after the launch of Bitcoin but accidentally threw away a hard drive on which the access key to his Bitcoin wallet was stored is
Man wants to search dump for lost hard drive with bitcoin fortune – here are his odds of finding it
https://theconversation.com/man-wants-to-search-dump-for-lost-hard-drive-with-bitcoin-fortune-here-are-his-odds-of-finding-it-249889
James Howells, an IT engineer living in the UK, is considering buying an entire waste disposal facility to get his lost bitcoins. He was one of the five people mining bitcoins in 2008, and had mined about 8,000 BTC by February 2009, but had forgotten about it after quitting mining.
Then, in 2013, when Howells learned that Bitcoin was skyrocketing, he realized that he had accidentally thrown away the hard drive that contained the private key to access the wallet. Since then, he has been searching for the hard drive sleeping in the waste disposal site for more than 10 years, and even though he has mobilized a search team using robot dogs and AI, he has not been able to find it. He said that he is considering purchasing the waste disposal site when the local government closes it.
A man who keeps searching for a hard drive containing 23 billion yen worth of bitcoin at a garbage disposal site invests 1.6 billion yen to hire a robot dog and an AI expert - GIGAZINE
Craig Anderson, a senior lecturer in statistics at the University of Glasgow in the UK, calculated the probability of finding a palm-sized hard drive in a pile of rubbish estimated to weigh 1.4 million tonnes.
First of all, the Docksway landfill, where Howells' hard drive is believed to be buried, has an area of about 500,000 square meters, equivalent to 70 football fields. And the depth of the rubbish that has piled up over the years is conservatively estimated at 20 meters, with a total volume of 10 million cubic meters (10 trillion cubic centimeters). This is about 3,600 times the size of the swimming pool used for the 2024 Summer Olympics in Paris.
On the other hand, the HDD that Howells lost is 2.5 inches, so its size is about 70 cubic centimeters (7 cm x 10 cm x 1 cm). Therefore, the probability of finding a HDD in one place is '70 ÷ 10 trillion = 0.000000000007', or about 1 in 143 billion.
by Robin Drayton / Newport City Landfill Site / CC BY-SA 2.0
That's a 1 in 3,000 chance of winning the UK lottery, but with so much money at stake, there's no way we're going to give up after searching a random location once. So Anderson did some quick math to see what it would look like if we thoroughly searched a landfill.
According to the calculations, even if you were to check every 1,000 cubic centimeters of garbage for a hard drive every second, it would take 10 billion seconds, or 316 years, to search the entire garbage dump. In other words, if you were to search around the clock, your chances of finding a hard drive in a year would be 1 in 316.
To gauge whether Howells's hard drive is worth the effort, we need to turn to the statistical concept of 'expected value,' which is a measure of the long-term return expected when a certain scenario is repeated.
For example, consider the expected value of a gamble where if you roll a 6 on the dice, you get 200 yen, but if you roll any other number, you have to pay 100 yen. In this case, the expected value (E) is 1/6 x 200 yen + 5/6 x (-100 yen) = 200/6 - 500/6 = -50 yen, which means you lose 50 yen each time you bet, so it's a bad bet.
Similarly, let's calculate the expected value of searching for Howells' HDD in a year. If the HDD is found, 8000 BTC will be obtained, and if it is not found, nothing will be obtained, so the calculation is 'E = 1 / 316 x 8000 BTC + 315 / 316 x 0 BTC = about 25.3 BTC (about 300 million yen)'. In other words, if the annual cost of searching for a waste disposal site is less than this expected value, you can expect a profit, but if it is more, there is a high risk of incurring a loss, so you should not go to such lengths to search for the HDD.
However, these calculations are based on the assumption that one person would search a vast waste disposal site day and night, so the actual costs and returns will vary greatly depending on the exact size of the site, the search time, the number of people involved, etc.
Anderson ended his article by saying, 'If Mr. Howells ever has access to the dump, it might be worthwhile to have a statistician assist him in the search. I would be happy to offer my services for a small fee...'
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in Note, Posted by log1l_ks