It's safe to say that Turing Award winners know a thing or two about computing, so when they express concern about key trends in the tech world, it's worth paying attention.
That, in fact, is just what three award winners did this week at the Heidelberg Laureate Forum in Germany, where they were gathered along with other leading thinkers in the fields of mathematics and computer science.
RSA encryption algorithm co-inventor Leonard Adleman, "Father of the Internet" Vint Cerf, and cryptography innovator Manuel Blum all shared their biggest fears.
"I worry a lot about the potential loss of openness and freedom on the Internet," Cerf said.
Those qualities have allowed the Internet to enable the sharing of information on an unprecedented scale, and also to spawn new business models. For example, eBay created global auctions that wouldn't have been possible otherwise, he pointed out.
"This sharing of information is an extremely important part of the Internet's character, and I'd be very unhappy if that were to diminish," he said.
Current debate over the "right to be forgotten" is particularly tricky, added Cerf, who is now vice president and chief Internet evangelist at Google.
"The other side of that coin is the freedom of people to know things they should know, and I don't think that side is getting as much visibility as it should," he said. "It's just as important as the question of removing harmful information from the Internet."
As the debate progresses and decisions are made, "I'm hoping we won't lose sight of the value of the network for knitting together people and ideas around the world," Cerf said. "If we lose that, we lose something of great value."
Also on Cerf's list of tech "nightmares" is the prospect of an impending "digital dark age."
Not only is the current domain name system unstable, potentially creating a future filled with broken links from the past, but there is a threat to digital content of all kinds, he said. "We don't have a regime that will allow us to preserve both the content and the software needed to render it over a very long time."
Anyone with digital photos should be concerned, Cerf warned.
We're just as dependent on the software as on the data itself, so "what happens if 100 years from now the digital files are still around, having been dutifully copied from one medium to another, but the software is no longer available or supported?" he said. "I don't think we as an industry have fully internalized how important this is going to be."
Also necessary are legal frameworks and a business model that could help support that preservation, he noted.
Cerf's recommendation in the meantime? Print your photos on high-quality photographic paper. "There's evidence that will last 100 years, but we're not so sure about digital media," he said.
Adleman worries about the rapid evolution of computers, which he suspects will become our evolutionary successors.
"I wonder what our relationship to computers will be in 100 or even 50 years," he said. "I'm leaning towards the view that computers will be roughly speaking their own species."
What relationship they'll have to our species, however, is not so clear.
"Right now the relationship is mostly synergistic -- we build them and they serve us," he said. "But how it will evolve in the future is quite unclear to me."
Computers will "probably have their own destinies and find their own ways to evolve," he said. "They may not need artificial intelligence to become independent."
Along similar lines, Blum views computers as our ultimate progeny in the not-too-distant future; his current worries tend to focus on the fact that they're not yet in charge of driving all cars and airplanes.
"The fact that we have brains hasn't made the world any safer," he said. "Will it be safer with computers? I don't know, but I tend to see it as hopeful."
Though Blum is an expert in cryptography, he's not particularly worried about privacy. "I find the fact that cameras are everywhere is helpful," he said, citing the example of the Boston Marathon bombers. "It's wonderful that you can find pictures and know who they are."
In fact, it remains to be seen whether future generations will be able to expect any privacy at all, Adleman said.
"There's a huge prospect for wondrous things for humans: health will improve, and maybe longevity," he said. "But the younger generation is going to have to live with the good and the bad."
Due to a reporting error, the name of RSA encryption algorithm co-inventor Leonard Adleman was misspelled in an earlier version of this story.