How is this possible? (Blockchain.info block sequence)

[colinistheman]

How is this possible? Just curious...

[12648430]

It's impossible to determine the actual age of a block. Blockchain.info just uses the blocks' timestamps, which are set by the nodes that mine the blocks; the network requires that a node's clock not be waaay off but doesn't require everyone's clocks to be exactly in sync. So if you're computer's time is 20 minutes fast and you mine a block it'll look something like that.

[zimmah]

someone has the computer clock on a wrong time, in the end it doesn't matter.

[bitpop]

I don't know what im looking at: ?

[Peter R]

As the others said: someone's clock is wrong. 

OP: have you had a chance to study the original Satoshi white paper?  It is a surprisingly easy read.  He briefly talks about the time-keeping requirements. 

It amazes me how robust the bitcoin network is (and this time-keeping issue is one example of its robustness).