Drive up or down a twisty mountain road and that adds height, so that's travelling in all three dimensions. But how on Earth do we travel in time? How do we find a path through the fourth dimension? Let's indulge in a little science fiction for a moment. Time travel movies often feature a vast, energy-hungry machine. The machine creates a path through the fourth dimension, a tunnel through time. A time traveller, a brave, perhaps foolhardy individual, prepared for who knows what, steps into the time tunnel and emerges who knows when.
The Future of Zero-Gravity Living Is Here | Science | Smithsonian
The concept may be far-fetched, and the reality may be very different from this, but the idea itself is not so crazy. Physicists have been thinking about tunnels in time too, but we come at it from a different angle. We wonder if portals to the past or the future could ever be possible within the laws of nature. As it turns out, we think they are. What's more, we've even given them a name: The truth is that wormholes are all around us, only they're too small to see. Wormholes are very tiny. They occur in nooks and crannies in space and time. You might find it a tough concept, but stay with me.
A wormhole is a theoretical 'tunnel' or shortcut, predicted by Einstein's theory of relativity, that links two places in space-time - visualised above as the contours of a 3-D map, where negative energy pulls space and time into the mouth of a tunnel, emerging in another universe. They remain only hypothetical, as obviously nobody has ever seen one, but have been used in films as conduits for time travel - in Stargate , for example, involving gated tunnels between universes, and in Time Bandits , where their locations are shown on a celestial map. Nothing is flat or solid.
If you look closely enough at anything you'll find holes and wrinkles in it. It's a basic physical principle, and it even applies to time. Even something as smooth as a pool ball has tiny crevices, wrinkles and voids. Now it's easy to show that this is true in the first three dimensions. But trust me, it's also true of the fourth dimension. There are tiny crevices, wrinkles and voids in time.
Down at the smallest of scales, smaller even than molecules, smaller than atoms, we get to a place called the quantum foam. This is where wormholes exist. Tiny tunnels or shortcuts through space and time constantly form, disappear, and reform within this quantum world.
And they actually link two separate places and two different times. Unfortunately, these real-life time tunnels are just a billion-trillion-trillionths of a centimetre across. Way too small for a human to pass through - but here's where the notion of wormhole time machines is leading. Some scientists think it may be possible to capture a wormhole and enlarge it many trillions of times to make it big enough for a human or even a spaceship to enter.
Given enough power and advanced technology, perhaps a giant wormhole could even be constructed in space. I'm not saying it can be done, but if it could be, it would be a truly remarkable device. One end could be here near Earth, and the other far, far away, near some distant planet. Theoretically, a time tunnel or wormhole could do even more than take us to other planets. If both ends were in the same place, and separated by time instead of distance, a ship could fly in and come out still near Earth, but in the distant past. Maybe dinosaurs would witness the ship coming in for a landing.
Now, I realise that thinking in four dimensions is not easy, and that wormholes are a tricky concept to wrap your head around, but hang in there. I've thought up a simple experiment that could reveal if human time travel through a wormhole is possible now, or even in the future. I like simple experiments, and champagne. So I've combined two of my favourite things to see if time travel from the future to the past is possible. Let's imagine I'm throwing a party, a welcome reception for future time travellers.
But there's a twist. I'm not letting anyone know about it until after the party has happened. I've drawn up an invitation giving the exact coordinates in time and space. I am hoping copies of it, in one form or another, will be around for many thousands of years. Maybe one day someone living in the future will find the information on the invitation and use a wormhole time machine to come back to my party, proving that time travel will, one day, be possible.
In the meantime, my time traveller guests should be arriving any moment now. Five, four, three, two, one. But as I say this, no one has arrived. I was hoping at least a future Miss Universe was going to step through the door. So why didn't the experiment work? One of the reasons might be because of a well-known problem with time travel to the past, the problem of what we call paradoxes.
Paradoxes are fun to think about. The most famous one is usually called the Grandfather paradox. I have a new, simpler version I call the Mad Scientist paradox. I don't like the way scientists in movies are often described as mad, but in this case, it's true.
How fast could humans travel safely through space?
This chap is determined to create a paradox, even if it costs him his life. Imagine, somehow, he's built a wormhole, a time tunnel that stretches just one minute into the past. Hawking in a scene from Star Trek with dinner guests from the past, and future: Through the wormhole, the scientist can see himself as he was one minute ago.
It just doesn't make sense. It's the sort of situation that gives cosmologists nightmares. This kind of time machine would violate a fundamental rule that governs the entire universe - that causes happen before effects, and never the other way around. I believe things can't make themselves impossible. If they could then there'd be nothing to stop the whole universe from descending into chaos. So I think something will always happen that prevents the paradox. Somehow there must be a reason why our scientist will never find himself in a situation where he could shoot himself. And in this case, I'm sorry to say, the wormhole itself is the problem.
In the end, I think a wormhole like this one can't exist. And the reason for that is feedback. If you've ever been to a rock gig, you'll probably recognise this screeching noise. What causes it is simple. Sound enters the microphone. It's transmitted along the wires, made louder by the amplifier, and comes out at the speakers. But if too much of the sound from the speakers goes back into the mic it goes around and around in a loop getting louder each time.
If no one stops it, feedback can destroy the sound system. The same thing will happen with a wormhole, only with radiation instead of sound. As soon as the wormhole expands, natural radiation will enter it, and end up in a loop. The feedback will become so strong it destroys the wormhole. So although tiny wormholes do exist, and it may be possible to inflate one some day, it won't last long enough to be of use as a time machine. That's the real reason no one could come back in time to my party. Any kind of time travel to the past through wormholes or any other method is probably impossible, otherwise paradoxes would occur.
So sadly, it looks like time travel to the past is never going to happen. A disappointment for dinosaur hunters and a relief for historians. But the story's not over yet. This doesn't make all time travel impossible. I do believe in time travel. Time travel to the future.
Time flows like a river and it seems as if each of us is carried relentlessly along by time's current. But time is like a river in another way. It flows at different speeds in different places and that is the key to travelling into the future. This idea was first proposed by Albert Einstein over years ago.
- Through the wormhole;
- Le Talon de fer (French Edition);
- Con la Misma Piedra;
- Navigation menu?
- El Príncipe de Maquiavelo: ¿Se puede aplicar las ideas de Maquiavelo en la actualidad? (Spanish Edition)?
- Accessibility links!
He realised that there should be places where time slows down, and others where time speeds up. He was absolutely right.
And the proof is right above our heads. A network of satellites is in orbit around Earth. The satellites make satellite navigation possible. But they also reveal that time runs faster in space than it does down on Earth. Inside each spacecraft is a very precise clock. But despite being so accurate, they all gain around a third of a billionth of a second every day. The system has to correct for the drift, otherwise that tiny difference would upset the whole system, causing every GPS device on Earth to go out by about six miles a day. You can just imagine the mayhem that that would cause.
The problem doesn't lie with the clocks. They run fast because time itself runs faster in space than it does down below. And the reason for this extraordinary effect is the mass of the Earth. Einstein realised that matter drags on time and slows it down like the slow part of a river.
The heavier the object, the more it drags on time. And this startling reality is what opens the door to the possibility of time travel to the future. Right in the centre of the Milky Way, 26, light years from us, lies the heaviest object in the galaxy. It is a supermassive black hole containing the mass of four million suns crushed down into a single point by its own gravity. The closer you get to the black hole, the stronger the gravity. Get really close and not even light can escape.
A black hole like this one has a dramatic effect on time, slowing it down far more than anything else in the galaxy. That makes it a natural time machine. I like to imagine how a spaceship might be able to take advantage of this phenomenon, by orbiting it. If a space agency were controlling the mission from Earth they'd observe that each full orbit took 16 minutes.
But for the brave people on board, close to this massive object, time would be slowed down. And here the effect would be far more extreme than the gravitational pull of Earth. The crew's time would be slowed down by half. For every minute orbit, they'd only experience eight minutes of time. Around and around they'd go, experiencing just half the time of everyone far away from the black hole. The ship and its crew would be travelling through time. Imagine they circled the black hole for five of their years.
Ten years would pass elsewhere. When they got home, everyone on Earth would have aged five years more than they had. So a supermassive black hole is a time machine. But of course, it's not exactly practical. It has advantages over wormholes in that it doesn't provoke paradoxes. Plus it won't destroy itself in a flash of feedback. But it's pretty dangerous.
It's a long way away and it doesn't even take us very far into the future. Fortunately there is another way to travel in time. And this represents our last and best hope of building a real time machine. You just have to travel very, very fast. Much faster even than the speed required to avoid being sucked into a black hole. This is due to another strange fact about the universe.
There's a cosmic speed limit, , miles per second, also known as the speed of light. Nothing can exceed that speed. It's one of the best established principles in science. Believe it or not, travelling at near the speed of light transports you to the future.
To explain why, let's dream up a science-fiction transportation system. Gravity—or, more precisely, resistance to gravity—is the force that gives our muscles their power, and gives our bones their strength and durability. Older women on Earth lose about 1 percent of their bone mass a year.
So Space Station astronauts exercise two-and-a-half hours a day, and NASA schedules exercise as a part of the daily work routine. Largely because of such physiological challenges, the question of how to get astronauts to Mars and back, about an eight-month flight each way, remains unresolved. And none of this addresses the psychological difficulties of prolonged space travel: It takes a certain type of person.
I mean, you need to be a very multi-skilled, well-rounded individual who can also deal very well with adversity. Three days after my tourist flight, I reboard G-Force One, along with six scientific research groups, to get a chance to observe others actually trying to get some work done in weightlessness. What the jet achieves is controlled, high-speed free-fall. During the brief interval when the plane approaches the top of the parabola and noses over, the plane falls out of the way of its occupants at exactly the same rate its passengers are falling to Earth, and for those seconds, the aircraft wipes away the effect of gravity.
G-Force One gives scientists their best chance to work in zero gravity without having to go to the Space Station, and they pay tens of thousands of dollars, often using grants from NASA, for the privilege of performing experiments 27 seconds at a time. One group, led by an emergency room doctor from Richmond, Virginia, and assisted by undergraduates from Purdue University, is testing a system for reinflating a collapsed lung in zero gravity, complete with pints of expired blood. The Zero Gravity staff installs straps and handholds near the experiments, so researchers can work their equipment or tend their laptops as the plane soars in and out of zero gravity.
But no matter how much planning has been done, how veteran the crews are or how much Velcro the equipment is secured with, the first flight parabolas are total chaos. Marsh Cuttino, the Virginia doctor leading the lung experiment, sets up his equipment near the back of the plane. The procedure is relatively straightforward in an Earth-bound ER. Cuttino and his students video the process so they can study how the blood flows through the device, which is impossible to observe in detail when flying up and over 25 parabolas.
Paul Reichert, a research scientist at Merck pharmaceuticals, has been an advocate for zero gravity drug development for 25 years. Weightless drug manufacturing, he says, would enable engineers to better control chemical processes, especially when it comes to synthesizing complicated large-molecule medicines. Reichert has never left Earth, but he has designed more than a dozen experiments performed by astronauts aboard the space shuttle and the International Space Station. Still, progress is slow.
Kelly hopes that more pharmaceutical experiments will be done on the Space Station, but he says an even better research site is the Moon: One of the most alluring opportunities for transforming exploration in Earth orbit and beyond comes from an old industry—mining. Even near space is full of rocks containing huge amounts of precious materials, including metals such as iron, gold and platinum.
Before he co-founded the company, in , Lewicki spent nine years as a NASA engineer, including as flight director of the Mars rovers Spirit and Opportunity. For the time being, Planetary Resources is focused on arguably the most valuable resource for space exploration—water, which can easily be separated into hydrogen and oxygen to make rocket fuel.
An asteroid as small as a kilometer across could contain enough water to make more fuel than has been used by all the rockets ever launched, Lewicki says. Space outposts will also need water for drinking, sanitation and as a source of oxygen, for breathing. Just harvest the ice robotically and haul it back to a mostly automated processing facility, where a handful of human tenders might cycle in for short stints of a few weeks at a time. Not to bring to Earth, but to use in space.
Planetary Resources is a few years from launching its first prospecting satellite, which will scout for water on nearby asteroids. And Lewicki acknowledges that a series of technological innovations, from robot asteroid miners to refillable rocket fuel tanks, need to be developed before a self-sufficient space economy takes hold. But he insists it will happen, and asteroid mining will play a critical role: But how it transformed personal and commercial transportation in the U.
Lewicki believes the vision of a new space economy is real. A few parabolas into my G-Force One tourist flight, I arrange myself face-down instead of on my back. As we soar over a crest, I feel gravity let go of my body, like being scanned by a force field. I ease into a sitting position. Others around me have begun to get the hang of it and are doing tricks. Someone drifts my way and I redirect him with a single touch. During the next loop, I fish a notebook from my thigh pocket and park it in the air right in front of me while I retrieve a pen from another pocket.
Instead you are totally released from all force, from all pressure—in zero gravity, you have the freedom of a helium balloon, you are the helium balloon, and you can feel that sense of freedom, not just in your gut but in your joints, your muscles, on your skin, inside your mind. This article is a selection from the June issue of Smithsonian magazine.
Subscribe or Give a Gift. Who is the New Jamestown Skeleton? Science Age of Humans. The Art of Secrets and Surveillance. At the Smithsonian Visit. Photos Submit to Our Contest. Photo of the Day. Subscribe Top Menu Current Issue. College students load scientific cargo onto G-Force One. Cuttino and his assistants bottom right. Behind them, scientists test a robot for spaceship maintenance.