Look at the number of media that just can't be read nowadays, even what we think of as recent (the floppies above) - Look at the panic surrounding the Doomsday Disk, which I'm sure you remember playing around with as a kid..

I wouldn't even like to take a guess at what the future will look like.

The absolute and only way be to be sure that your photos are preserved is by owning and managing your own content. In practice I figure this means storing digital copies in a physical place in as many formats as possible.

This solution is actually based on optimism, as all kinds of doom scenarios could ruin the preservation, including wars, natural disaster of self destruction of our species.

I wonder if you are actually considering the state of technology in such a huge timeline. Hard to imagine now, but it is likely that you can preserve your very virtual being within a few decades. It would look like you, speak like you, think like you, like the things you liked and more. I know, it's very sci-fo but Scott Adams has a cool blog entry about it:

http://dilbert.com/blog/entry/your_digital_ghost/

With digital cameras, we can take a large quantity of pictures. But 100 years from now, I don't think my great-great-great grandkids will care if they don't have all 15 poses of me with my new car, or every single landscape shot from my vacation. A few really good shots should do fine. (Putting those into a acid-free scrapbook with some handwritten explanations would be even better...but we can't all be Martha Stewart.)

THAT photo survived 120 years, but how many didn't?

Also, it didn't cost *nothing* to store that photo. It did take up space somewhere, it may have had to be moved to new locations, and it needed someone to remember where it was stored. (None of those issues are magically resolved with digital media, but they have different solutions.)

Obviously the format issue is of concern. All I can hope for is that as long as it's digital, it can be quickly migrated to newer standards if necessary. Printing and storing important pictures is probably not a bad idea, to date that seems to be s the only format that doesn't need any translation/device/technology to be viewed.

The same thing can bite you with respect to hardware - the other day I was rooting around in my closet and found a box of 5 1/4" floppies. Is there anything important on there? I doubt it, but I have no way of finding out - I no longer have any 5 1/4" drives in the house, and even if I were to come up with one, I'm not sure where I'd get a driver for it.

Of course, paper has its pitfalls too - unless you're careful to print on archival (acid-free) paper and store it correctly, your printed photos will crumble before 100 years go by.

The bottom line is that long-term storage of photos is a tricky problem, and it's not obvious to me what to do about it.

This certainly isn't true of a digital photo printed using a desktop inkjet printer, they will start significantly changing only a few years after being printed.

After some explanation, she raised up and left the living room, a few minutes later she returned with a post card, send by her daughter some 50 years ago.

The text on the card said: "I call you this afternoon.". So my grandma could be ready at the phone which she and granddad shared with the other families in the building.

Back then the postman came twice a day, now we are lucky to see him twice a week. And I'm pretty sure none of my emails will exist in 50 years from now. Especially not the phone messages.

In 1985, a mere 26 years ago, a 5MB Harddisk (yes, 5 Megabytes, enough room for 1 photo of an el cheapo cam today) would have cost you around 400 Euros (would be 540 US$ today, don't know the exchange rate back then). That's 8 million Euros or 10.8 million dollars for your 100GB Dropbox if it was local storage. And Marty McFly, who I believe is due to visit us Back in the future next year coming from 1985 would have asked you what that internet is that you keep talking about.

So I think yes, your photos will be around if anyone wants to keep them and the storage will probably be even cheaper than your tin can.

Thomas