Dana Nemcova, Jiri Gruntorad and Jan Ruml are former Czech dissidents who signed the Charter 77 Manifesto, which sought to “enable all citizens of Czechoslovakia to work and live as free human beings.”

In this Internet age, all of us are everywhere, whether in person, via telephone, by e-mail or text message, or in pictures online.

Despite our connectedness, one of the world’s most famous people, China’s most prominent dissident, Liu Xiaobo, has vanished.

Liu was arrested Dec. 8, 2008, and sentenced to 11 years in prison for his role in the creation of Charter 08 , a human rights and democracy petition modeled on Charter 77, our manifesto for liberty under communist Czechoslovakia.

Charter 08 garnered worldwide attention and thousands of signatures inside China. But even the 2010 Nobel Peace Prize was not enough to bring Liu into the light, though his picture was on the front page of newspapers worldwide — save those in China.

During more than five years in jail, not a single picture has emerged of Liu, nor has he been able to make any direct statement to the larger world. Little is known about the conditions of his detention in China’s northeast Liaoning Province.

Only a handful of people — including his wife and his lawyers — have seen him. His works remain banned from publication in China, and even speaking his name in public is frowned upon.

Liu Xia, Liu Xiaobo’s wife, has herself been placed in a virtual cage. Although she has not been charged with a crime, she is under constant surveillance and has repeatedly been blocked from speaking about Liu’s plight with fellow activists or with journalists. To China’s Communist Party, her silence is a necessary component of her husband’s disappearance. If she could speak to the world about his plight, Liu would be somewhat visible.

The party has created this wall of silence in hopes that, for as long as Liu is out of sight, he will be out of mind, especially within China. Although the men who run China have embraced modernity in many ways, they cling to one of the most commonly used authoritarian tools: the creation of an alternate reality, one in which, for their own subjects at least, some people and some ideas are not allowed to exist.

The three of us know something about how authoritarian regimes attempt to stitch together new worlds in which inconvenient or dangerous truths are wiped away, along with those who would speak them.

In Czechoslovakia in the 1970s and 1980s, friends of ours were jailed, sometimes for years, merely for speaking words or names that had been declared forbidden. For decades, we waged a seemingly endless intellectual insurgency, using samizdat magazines and house meetings to fight the state’s ideational and individual extermination campaign.

Even fundamental societal values such as trust, brotherhood and love were regularly attacked by those who ran the Czechoslovak Socialist Republic: The absence of these values would make the population more cynical, more withdrawn and thus easier to control.

We were, in the words of our late comrade Vaclav Havel, accidental dissidents. As he wrote many years ago, “We never decided to become dissidents. We have been transformed into them, without quite knowing how.” A sense of keeping faith with our comrades, our values and our country determined our actions. “We simply went ahead and did certain things we felt we ought to do, and that seemed to us decent to do, nothing more nor less,” he wrote.

We wonder whether Liu, a former literary critic who has stood by those who lost loved ones in Tiananmen Square in 1989, has had similar thoughts.

It is not known how much the Chinese government has spent not only to keep Liu in jail but also to erase his name from public discourse. State-induced systemic amnesia is much more difficult, and costly, in the Internet age than it was in the days of the Eastern Bloc.

Yet for all of that money, the ideas that Liu promoted are more popular than ever. There has been a wide-ranging debate within China over the past year on the need for constitutionalism, a thinly veiled proxy for the ideas advanced by Liu and Charter 08. Other prominent intellectuals are taking to weibo, the Chinese version of Twitter, to fill the space left by Liu’s absence. Chinese youth, tired of online censorship and fed up with official corruption, are drinking in these ideas.

Liu may be invisible outside his prison cell, but the values he spent a lifetime championing are acknowledged by a growing number of Chinese as a key element of China’s future politics.

The Chinese government should bow to this reality and free Liu. He should be allowed to again take part in the conversation for democratic reform that he has done so much to foster.