Brian Greene, professor of physics and mathematics at Columbia University and co-founder of the World Science Festival, explains what we know about time travel so far. Following is a transcript of the video.

Brian Greene: “I’m Brian Greene, professor of physics and mathematics at Columbia University and co-founder of the World Science Festival.

“It’s critical that you realize that there are two types of time travel, and they are radically different. Time travel to the future? Definitely possible.

“We know how to do it because Einstein showed us the way over a hundred years ago. It’s surprising how few people actually really know about this in their bones. He showed that if you go out into space and travel near the speed of light, and you turn around, and you come back, your clock will be ticking off time more slowly. So, when you step off it’s going to be the future on planet Earth. You will have time traveled into the future.

“He also showed that if you hang out near a nice strong source of gravity — a neutron star, a black hole — and you kind of get right near the edge of that object, time also for you would slow down real slow relative to everybody else. And therefore, when you come back to Earth, for instance, it’ll again be far into the future.

“This is not controversial stuff. Any physicist who knows what they’re talking about agrees with this. But the other kind of time travel — to the past is where the arguments start to happen because many of us don’t think that time travel to the past is possible.

“The main proposal that people at least consider worthy of attention for traveling to the past does make use of a weird concept called wormholes. A wormhole is something that really … Albert Einstein again discovered. The guy has like got his name written over everything in this field.

“It’s a bridge, if you will, from one location space to another. It’s kind of a tunnel that gives you a shortcut to go from here to here. Now he discovered this in 1935 but it was subsequently realized that if you manipulate the openings of a wormhole — put one near a black hole or take one on a high-speed journey — then time of the two openings of this wormhole tunnel will not take off at the same rate, so that you will no longer just go from one location in space to another, if you go through this tunnel — through this wormhole — you’ll go from one moment in time to a different moment in time. Go one way, you’ll travel to the past, the other way, travel to the future.

“Now again, we don’t know if wormholes are real. We don’t know if they are real whether you’ll be able to go through them. So, there are all sorts of uncertainties here. Most of us think that you’re not going to actually go on a whirlwind journey through a wormhole to the past. But it’s still not ruled out.”

Sources:- independent.co.uk

An expert human pilot was successfully able to beat flying drones controlled by artificial intelligence (AI) systems in a race organized by NASA. However, the AI-driven drones were more consistent in their performance, scientists said.

Drone racing is a high-speed sport demanding instinctive reflexes. Researchers at NASA’s Jet Propulsion Laboratory (JPL) in the US put their work to the test recently. Timing laps through a twisting obstacle course, they raced drones controlled by AI against world-class drone pilot Ken Loo.

The team built three custom drones – dubbed Batman, Joker and Night wing – and developed the complex algorithms the drones needed to fly at high speeds while avoiding obstacles. The drones were built to racing specifications and could easily go as fast as 129 kmph in a straight line. However, on the obstacle course set up in a JPL warehouse, they could only fly at 48 to 64 kilometers per hour before they needed to apply the brakes.

“We pitted our algorithms against a human, who flies a lot more by feel,” said Rob Reid of JPL, the project’s task manager. “You can actually see that the AI flies the drone smoothly around the course, whereas human pilots tend to accelerate aggressively, so their path is jerkier,” Reid said. Compared to Loo, the drones flew more cautiously but consistently. Their algorithms are still a work in progress.

For example, the drones sometimes moved so fast that motion blur caused them to lose track of their surroundings. Loo attained higher speeds and was able to perform impressive aerial corkscrews. However, he was limited by exhaustion, something the AI-piloted drones did not have to deal with.

While the AI and human pilot started out with similar lap times, after dozens of laps, Loo learned the course and became more creative and nimble.

These technologies might allow drones to check on inventory in warehouses or assist search and rescue operations at disaster sites. They might even be used eventually to help future robots navigate the corridors of a space station.