this is part of the non-profit internet archive brain brainchild of internet brewster kahle. >> robot crawlers will contact every web page and every website every two months taking a snapshot. it's starting to get big. >> how big? >> we've been archiving a billion page as week at this point. we're about 450 billion pages that are able through the way back machine. enormous. >> the online way back machine allows anyone to rummage through digital decades gone by. >> you type in a web address and then it shows one of the past versions of them. and you say i want to serve the web as it was in 2004 or in 1998. and go in and explore the ideas to try to keep the web alive even though the servers may be long gone. >> but unlike books in a library or in inscriptions carved in stone, the internet is really just a bunch of electrons blipping around. that raises questions about digital durability. many specialists are deeply concerned that as hardware, software and computer coding languages change over time, vast amounts of knowledge may essentially be lost, locked in obsolete digital formats tha

this is part of the non-profit internet archive brainchild of digital pierre brewster kahl. >> the digital archive has been archiving the worldwide web since '96. there are robot crawlers going to every website every two months take a snapshot, and everyagain snapshot, snapshot. it's starting to get big to go we archive 1 billion page as week. we're 450 billion pages available through the way back machine. it's enormous. another his online way back machine allows anyone to rummage through digital decades gone by. >> you type in a web address then it shows what are the past versions of them. you select the time and you say i want to serve the web as it was and take 2004 or 1998. and go and explore the idea to try to keep the web alive even though the servers may be long gone. >> but unlike books in a library or in inscriptions carved in stone, the internet is really just a bunch of electrons flipping around. that raises questions about digital durability. many specialists are deeply concerned that as hardware, software and computer coding languages change over time, vast amounts of knowledg

brewster kahle to preserve the internet, cat videos and all. >> you can keep up-to-date with all the developing stories. we're particularly looking at the talks taking place in brussels. we're looking at athens where they're preparing for a referendum and then the crucial talks in vienna. www.aljazeera.com. the science of fighting a wild-fire. we're going to explore the intersection of hardware and humanity and we're doing it in a unique way. this is a show about science by scientists. tonight, techknow investiages dirty gold. see the color of this river? this is not normal. inside the illegal gold trade. profits are enormous destruction, immediate. but, what happens to that gold once it leaves peru? we have two of these gold chains in front of you. just by looking at the chain itself, can you tell if either of these are dirty? what would be your quess? i'm phil torez, i'm an entomologist. i do much of my research in this territory. they've tested the water they've tested the sediment. i'll share my findings with marita davison. she's an environmental biologist. >> what size of an ar