Quote from: jongameson on December 05, 2013, 06:34:19 PM

Quote from: Kevlar on December 05, 2013, 01:35:04 AM

It's impossible to send them to an invalid address, BUT it's entirely possible to send them to an address for which no one has the key.

Take for example: 1BitcoinEaterAddressDontSendf59kuE

Check it out on blockchain. If you can brute force the private key, the coins are yours. Is it impossible? Theoretically, no, but practically...

Let's say you had a super computer that was guessing 999 trillion keys per second. It would take you 3.5 billion years to exhaust just 10% of the keyspace, which means in 3.5 billion years you would have a 10% chance of having guessed the key. Good luck with those odds!

how do you know there's even a private address associated with that wallet? where did they calculate that address from?

"Nearly every 256-bit number is a valid private key. Specifically, any 256-bit number between 0x1 and 0xFFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFE BAAE DCE6 AF48 A03B BFD2 5E8C D036 4141 is a valid private key." -bitcoin wiki

If you know hexadecimal, then you can convert the above to hexadecimal and verify if it is a valid key with some (theoretical) private key associated with it.