Aging time travelers hypothetically

We already know how to build a time machine

In September 2015 the cosmonaut Gennady Padalka came back to earth for the last time. He had just completed his sixth mission in space and broke the record for most of the time out of Earth's atmosphere - 879 days. And because of those two and a half years of orbiting the planet at high speed, Padalka also became a time traveler who saw Einstein's theory of general relativity in action.

"When Mr. Padalka returned from his adventures, he found that the earth was 1 / 44th of a second in the future, which he hadn't expected," explains J. Richard Gott, Princeton physicist and author of the 2001 book Time Travel in Einstein's Universe, “He literally traveled ... into the future.”.

The fact that he was a fraction of a second younger than if he had stayed on earth is not exactly overwhelming, but it still gave Padalka the award as the “current time traveler record”.

Although you will search in vain for the plutonium-laden DeLorean, time travel is anything but fiction. Real astrophysicists like God are pretty sure they know how to build a time machine, and intense speed - much, much faster than Padalka's orbital excursion - is the key component.

A time travel crash course

Until the 20th century it was believed that time was completely immutable and that time travel was a scientific impossibility. In the 1680s, Sir Isaac Newton's time of thought progressed at a constant pace throughout the universe, regardless of external forces or location. And for two centuries the scientific world followed Newton's theory.

Until the 26-year-old Albert Einstein showed up.

In 1905 Einstein unveiled his ideas on special relativity and used this framework a decade later for his theory of general relativity. Einstein's universe-defining calculations introduced, well, many things, but also some time-related concepts. The most important thing is that time is elastic and depends on speed. Depending on how fast an object - or a person - is moving, it slows down or accelerates.

In 1971, four cesium beam atomic clocks flew around the world and were then compared to ground-based clocks. The resulting tiny time difference proved that Einstein was on the right track. There is one more technology hidden in smartphones that also confirms Einstein's theory.

“Without Einstein's general theory of relativity, our GPS system would not work.

... says Ron Mallet, an astrophysicist and author of Time Traveler: A Scientist’s Personal Mission to Make Time Travel a Reality. "This is also proof that Einstein's [theories] are correct."

But apart from this mutable version of time, Einstein also calculated the speed of light. At 300,000,000 meters (or 186,282 miles) per second, Einstein describes this number as the "ultimate speed limit" and a universal constant whether you are sitting on a bench or traveling in a rocket ship.

The last part of Einstein's ideas on time warping suggests that gravity also slows down time, which means that time moves faster where gravity is weaker, like the vast void between massive celestial bodies like the Sun, Jupiter and Earth.

A century later, and all these theories - highly summarized, of course - are now the building blocks of astrophysics, and buried between all this expert-level math, Einstein also proved that time travel is possible.

The subatomic time machine

In fact, time travel is not only possible, it has already happened - it just doesn't look like a typical sci-fi movie.

To get back to our time-traveling cosmonaut Padalka, his 1/44 second jump into the future is so tiny because he only covered 17,000 miles per hour. That's not very fast, at least compared to the speed of light. But what would happen if we could create something that could be much faster than geostationary orbit? We're not talking about an airliner (550 to 600 mph) or a 21st century rocket to the ISS (25,000 mph), but something that could be approaching at 186,282 mph?

"It has already happened at the subatomic level," says Mallett. “An example is… the Large Hadron Collider. It routinely sends subatomic particles into the future. "

The particle accelerator has the ability to propel protons at 99.999999 percent the speed of light, a speed at which their relative time moves about 6,900 times slower compared to their stationary human observers.

So, yes, we are sending atoms into the future, and have been for over ten years, but humans are a different matter.

God says that given that we regularly propel particles near the speed of light, it is conceptually quite easy for humans to travel to the future. "If you want to visit Earth in 3000," says God, "all you have to do is get on a spaceship and travel at 99.995 percent the speed of light".

Let's say a person is put on such a ship and sent to a planet a little less than 500 light years away (e.g. Kepler 186f), i.e. if he were to travel at 99.995 percent the speed of light it would take him about 500 years, to get there as it travels almost at the speed of light.

After a quick snack and a toilet break, one would then turn around and return to earth, which would take another 500 years. So in total it would take about a thousand years to get home safely. And on earth it would be the year 3018.

However, since you are moving so fast, the resulting time dilation would not seem like a thousand years because your internal clock has slowed down. “[Your] clock will be ticking at 1/100 the speed of the clocks on earth. They will only age about 10 years, ”says God. While a millennium would go by for us, it would be a decade on the other.

“If we [on earth] were watching through the window, they would have breakfast slooooooowly,” says God, “but everything would be normal for [them].

But there is a massive gap between what is theoretical and what is real. So how can we cope with the immense technological challenges involved in building a time machine?

The not too distant future of human time travel

Building a time-traveling spaceship might be the best place to start, but the technical obstacles, at least for now, are enormous. For one thing, we're not even close to having a spaceship that can fly at the speed of light.

In addition, there is the enormous amount of energy that would be required to move a ship so quickly. God suggests that highly efficient antimatter propellant could be key, and other world agencies and scientists believe that such propellant could be a potentially invaluable ingredient for interstellar travel.

But ensuring the safety of human cargo on such a futuristic mission would also be difficult. First of all, the ship would have to carry enough supplies, such as food, water and medicines, and be self-sufficient for the entire voyage.

Then there's the whole acceleration thing. To ensure that our hypothetical traveler is not wiped out by overwhelming G-forces, the ship would have to be accelerated gradually and steadily. While a constant acceleration of 1 g (as we perceive it on Earth) over a longer period of time would eventually cause the ship to approach the speed of light, this would lengthen the length of the voyage and minimize the distance to be expected in the future.

Taking our 500-light-year planet as an example, God predicts that the steady acceleration from 1g to almost the speed of light would increase the aging of the time traveler to 24 years, "but you would still be able to visit the earth in 3000", says God .

Building a vehicle to these specifications would require a great deal of time, resources, and money. The same also applies to other massively ambitious experiments, such as the detection of gravitational waves and the construction of the Large Hader Collider. A time machine could be the next scientific mega-project in the world.

The difficulty of going backwards

There's one major caveat, however, about this theoretical portrait of time travel in the real world - this machine doesn't go backwards. While Bill and Ted travel back in time to pick up on Socrates with relative ease, what scientists and researchers really have to do is find a way around the rules of physics to travel back in time.

Wormholes, black holes, cosmic strings, and circulating rays of light have all been suggested as possible solutions for time travel back in time. The biggest challenge astrophysicists face is figuring out how to strike a beam of light to a point in space-time and back.

Since the speed of light is the absolute maximum, the physicists concentrate on finding phenomena like wormholes that could offer tunnel-like shortcuts that jump through curved space-time and theoretically create this very ray of light.

While wormholes work within the confines of Einstein's theories of relativity, they have not yet been observed in space, and scientists have no concrete evidence that these galactic shortcuts would work at all.

So while time travel into the past may be the more exciting concept, scientists are far more likely to throw someone into the unknown future than into the trodden past. But despite the overwhelming opportunities - tax and science - Mallet believes the future of a time-traveling society is possible.

"What happened to the trip to the moon ... we wanted to go there, Kennedy asked, and there was adequate funding so we got there within a decade," says Mallet. “The technology is not far away. If the government and taxpayers were willing to pay for it, we could do it in the next twenty years, ”says Mallet.

For now, wannabe time travelers have yet to turn to science fiction to maintain their time travel fixation, with some films being much more accurate than others.

"A good movie ... was the original planet of the apes," says Mallett. “The astronauts thought they had landed on another planet that was ruled by monkeys, but what they found out…. was that they had traveled so fast that they had arrived in the future of the earth. This film accurately portrays Einstein's special theory of relativity. "