Deep Earth Exploration
The planet’s interior remains almost as much a mystery as it was when 23)Jules Verne wrote A Journey to the Center of the Earth. The deepest hole ever drilled is the 8-mile deep Kola Superdeep 24)Borehole in Russia， a modest achievement considering that the distance to the Earth’s center is nearly 4，000 miles. Deep Earth holds information that could make earthquake and 25)tsunami prediction a credible science as well as yield new insights into historic climate changes. But human exploration of the Earth’s interior will have to wait until technology can allow adventurers to survive the 26)searing heat and crushing pressure of Deep Earth.
Northeast 27)Greenland
Zoom in on Google Earth’s satellite image of Greenland and this message pops up： “We are sorry， but we don’t have imagery at this zoom level for this region.” Large sections of northeast Greenland remain unexplored， mainly because accessing the region is so expensive. There are mountains in Greenland’s Watkins range that have never been climbed； some peaks don’t even have names. New islands off the coast of Greenland are still being discovered as huge blocks of 28)glacial ice break away. Greenland also happens to offer a front row seat to the effects of global warming； ice is crumbling off the edge of the island at a rate of 20 billion tons a year， raising sea levels worldwide.
29)Subglacial Antarctica
We haven’t really been to Antarctica， we’ve only walked on top of the vast sheet of ice covering the continent. The interesting stuff is hidden beneath the two-mile thick continental 30)ice sheet. We know from satellite images that the world’s second largest lake lies beneath the Antarctic ice， as well as wide rivers， stony hollows， and 31)soggy land. Antarctica features a vast network of subglacial waterways that that could contain previously unknown forms of life. A team of Russian scientists is currently drilling through the ice sheet in an effort to take samples from one of the largest subglacial bodies of water， Lake Vostok. Finding a way to get a human explorer under the ice will be considerably more challenging， but just as there was a race to the Antarctic in the early 1900s， there may well be a race underneath the Antarctic in the future.
Time Travel
It’s 32)a long shot， but some of the world’s top physicists don’t think time travel is impossible. Einstein’s 33)special theory of relativity combines space and time into a single entity， space-time， which does not prohibit the notion. 34)Stephen Hawking has proposed using 35)wormholes to connect our universe with an infinite number of parallel universes， while others have 36)advanced 37)black holes or 38)cosmic strings as possible time-travel 39)portals. Of course， just because the laws of physics don’t prohibit time travel doesn’t mean it’s going to happen. But a journey in time would be the ultimate adventure， an utterly transformative experience for the universe.