Did you back up your brain today?

100 gigabytes.  That's how much it takes to store your entire genetic sequence.  The amazing double helixes of your DNA--the code that holds your hereditary pattern. 

Between pictures, music and movies, you're probably using a lot more than 100 gigabytes of storage.  The computer I'm writing this on has a 600 gigabyte hard drive.  You can go out and buy a terabyte or more right now.

50 years ago, or 20 years, or maybe even 10, this would have sounded like science fiction.  The DNA double helix was discovered in 1953, but it wasn't until 1977 that the first genome was completely sequenced, and that was for a bacteria.

Now you can store your entire genetic pattern on a hard drive.  In the future, will scientists and doctors be able to take this code and build another you? They've cloned sheep, and despite the ethical questions involved, I think it's a short matter of time before they clone a person.

Even if that clone had all your same physical attributes, it wouldn't be you because it hasn't had your experiences, your memories.  But what if we could store memories on a hard drive? How much space would that take?

Scientists estimate there are 100 billion neurons in the brain.  That sounds like an impossibly large number, until you consider how our concept of numbers is changing.  The first computer I used in school had 16 kilobytes of memory.  As the years rolled by, they went to 512KB, then one megabyte, and onward in relentless lockstep with Moore's Law.

Perhaps the day will come when you can back up your brain on a hard drive.  Then if you walk out the door and a falling satellite crushes you, your relatives could pay to have your memories installed on a 'blank'--a clone body with a brain empty of any experiences. 

But would it be you? Are we simply the sum of our DNA pattern coupled with our memories?

(The 100gb number came from the May/June 2012 issue of Technology Review.  I checked the DNA dates on Wikipedia, and the neuron number on Wolfram Alpha.)