How long does memory last?
There are lots of types of memory. The memory in our brains, our hard drives, our DNA, a carving on a tree or a rock. All these forms of memory are distinct not because of the things they store – that doesn’t matter, but how long they are stored for and how its contents are read in the future. Here some forms of memory with their pros and cons, and some ending thoughts on how to pass on this storage long after the world has ended.
Human Brain memory
lasts about 100 years, not reliable, accessible only by the individual storing it (unless explicitly expressed), can be crossed over into other means (i.e. stored in other media). Once a person is dead, the only way to access that memory is through their transfer of that memory to external devices (books, pictures, videos). Susceptible to drugs, psychology, age and things that kill humans. needs food and water to keep storage going.
5-7 years for a single spinning hard drive. SSD drives a little longer (lets be generous and say 10 years). Data is reliable (as time goes on, failure goes up), can be copied over to other hard drives with high accuracy. You could raid and do online backups that will make it significantly longer – but there are ongoing costs to that (membership). Relies on power to access memory, but does not need power to store it. Susceptible to strong magnets, water, fire, acids, etc.
Stored organically, very small, pretty resilient to the elements. Lasts a long time (at least 60,000 years – wooly mamoth DNA). Store large amounts (to date 700 terabytes / gram with a theoretical maximum of 455 exabytes / gram). For scale, humanity in its entirety creates about 2.5 exabytes of data per day. Technology is early on this, takes a long time to store and retrieve the data (like tape storage back in the day). Currently are not random access, re-writeable and have high latency. Susceptible to some extreme elements, but can be stored in containers that are very resistant.
Simplest form, can not store much information, easily accessible and does not need other tools to access/read. Lasts millions to billions of years (if it does not interact with other elements). Susceptible to extreme heat.
But what about when the earth is no longer? How will we transfer memory then? Let’s assume that we have not figured out significant space travel and can not have our storage on another site (i.e. another planet). The best viable option is storing the data into spores of DNA and ejecting them into space. Or maybe create billions of little machine probes and eject them in all directions with as much data as we can cram into them.
Fun musings for a Saturday night. I’m going to backup my hard drives online while I wait for DNA storage to come out, then I’ll fall asleep to some Carl Sagan documentaries.