# Is “Time Travel” to the future currently possible?

I was wondering if there is a realistic way that one can "travel" to the future, using today's technology.

Two scenarios I have thought of:

An individual is put under cryogenic freezing and then put into an artificially induced coma. His body and mind remain preserved for over 100 years, after which time he is taken out of cryogen and is awoken. Is this scenario unrealistic with current technology? What are the limitations of this?

Another scenario I thought of is where an individual travels in space on a spaceship. After traveling for say, 3 years, he returns to earth and 100 years have passed on earth. Thereby he "traveled into the future".

Are either of the scenarios realistically plausible with our current technology or in the very near future (next 10 years)?

Also, If anyone comes up with any other "realistic" scenarios for "time travel" I would love to hear them. These are just two I thought of.

• You're doing it now, one second per second. – Samuel Mar 5 '15 at 23:05
• Cross the international date line. – Aron Mar 6 '15 at 1:57
• I invented a special room I call it a 'closet'. You can go and sit in there to travel through time, after 60 minutes you have traveled 1 hour into the future! – bowlturner Mar 6 '15 at 13:40
• youtube.com/watch?v=ZknFhQftrug – apaul Mar 7 '15 at 16:42
• The nice point of Freezing is there's no deadline date. You can go to the fridge and wait until they eventually unfreeze you, and unless Earth falls into new Dark Ages or some apocalypse, they eventually will. (the Transmetropolitan comics touches this, with a story about people who only had their heads preserved, the body is rebuilt from DNA. – SF. Mar 25 '15 at 12:41

We do not currently have the technology for this.

Freezing

The first example is the most feasible, only because it shifts the hardest part to 100 years from now. We can freeze people, or their brains, and people provide this service today. The assumption is, that in 50 or 100 years we will have the technology to revive these frozen people. Oh, and also cure whatever killed them, because, yes, they're dead already. Perhaps we will eventually figure out how to revive these corpsicles. In fact, it seems there is nothing fundamentally stopping this, so it may just be a matter of time.

However, I suspect most people will see this as a bad thing because upon thawing you'll discover that everyone you knew is likely dead.

Unless you're an 80's guy. Just make sure to cure your boneitis.

Flying

The second example leaves out the most difficult detail, you have to travel at nearly the speed of light. This is not in our foreseeable future. It is right out not going to work any time soon. If we were ever to develop near light speed travel then yes, you could theoretically do this.

However, I suspect most people will see this as a bad thing because upon returning you'll discover that everyone you knew is likely dead.

Alternatives

Sending people to the future... I actually don't see this being a very useful topic of research in its own right. Cryogenic freezing or a similar suspension would be useful for long periods of space flight. But to use it to escape to the future seems like there is a different issue that needs to be looked at. Depressed, grass-is-always-greener, or simply impatient people would be the target market, I would think, and this would be a poor solution for them. A much better way to get to the future, in my opinion, is to live to it second by second.

• Freezing: The Door into Summer by Robert A. Heinlein. The guy doesn't go of his own free will. Kind of a fun story. Flying: you could get similar time travel effects without getting close to the speed of light by getting near a black hole and using it's time-space warping. There are several reasons why people would research ways to get into their consciousness into the future without dealing with subjective time. To cure disease, to escape cataclysm (a time ark), as an alternate to prison (life suspension as punishment). – AndyD273 Mar 6 '15 at 16:52
• @AndyD273 There is a reality-check tag here. So the Heinlein story doesn't help. A black hole of 10 solar masses would require you to sit just under 3km from the event horizon for three years to have 100 pass on Earth. We don't have the technology for that either. Disease might be a good reason, I can't imagine a cataclysm that could be jumped over successfully, and prisoners should experience subjective time (did no one learn from Demolition Man)? – Samuel Mar 6 '15 at 17:40
• Concerning flying, the problem is not flying at close to c, but rather actually reaching it. But for the sake of it I posted an answer calculating the acceleration/deceleration required to achieve those 100 years in 3 years, and it's merely 4-8g (depending on whether you go in circles or stop and return). The major problems are probably fuel (or other energy source) and plotting a course for the 2x4.6 ly travelled... – Zommuter Mar 25 '15 at 11:54
• A significant problem with "near-c travel" is energy required. With 100% efficient antimatter engine, to accelerate 2kg of mass to 0.86c you need to energy from annihilating 1kg of matter and 1kg of antimatter. Or good several tons of Plutonium. Simply, the ² in E=1/2 mv² really rains all over the parade when it comes to achieving high velocities. To double your speed you need to quadruple the energy spent. – SF. Mar 25 '15 at 12:38
• @TobiasKienzler Reaching a speed close to the speed of light is inherently part of moving at a speed close to speed of light. – Samuel Mar 25 '15 at 16:57

Another possible answer to add to the above from the bleeding edge of science: zombificatian/hibernation. Yes, this is a real thing. DARPA is experimenting with extending the "golden hour" between severe trauma and successful medical care. As part if that, they've discovered that they can put rats into suspended animation for long periods of time after losing 90% of their blood and still successfully bring them back to life for transfusion. It basically involves quickly shutting down the normal body process of death by replacing oxygen with another gas. Rather than standard apoptosis, the body enters a suspended animation state. They haven't done this with people yet, but it is currently working with animals.

Your character could be one of the first human test subjects.

Source: Wired article on zombie pigs

• DARPA experiments with just about everything, practical or not. – KSmarts Mar 6 '15 at 16:33
• @ksmarts Agreed, but in this case they actually have it working with smaller mammals, which is incredible. This isn't hypothetical tech, especially if the character can be put into a hyperbaric chamber for these purposes. Hey, we're already talking about time travel, so this isn't too farfetched. – Isaac Kotlicky Mar 6 '15 at 16:35

Recorded Resurrection

We don't have the ability to create bodies or upload minds now. But we might have the ability to sufficiently record them, using a combination of DNA sequencing and detailed medical scans. Then in the future, when humanity does have that ability, they could recreate you from scratch.

Not exactly what the topic is looking for I know, but might accomplish the same goal depending on your plot.

Let's calculate the required acceleration for you 100 years in 3 years scenario, fortunately Wikipedia provides the relevant formula:

when you start with v=0, where g is the constant acceleration. But you don't accelerate the whole time; upon your return you want to stop. And at half the travel distance, you probably have to stop and turn around, unless you fly in circles (of ever-increasing and then-decreasing radii due to the centrifugal force).

So, assuming the expression above holds symmetrically for deceleration, the most likely trip would be far away, stop and return, i.e. accelerate 0.75 years, decelerate 0.75 years to far away, and return the same way for 1.5 years, and each of those four phases should last 25 years on earth. That yields a required acceleration of 78.2 m/s², or about 8g. Potentially survivable, but for 3 years this sounds unpleasant.

Let's go in circles instead, so we only need to accelerate and decelerate once for 1.5 years each, both taking 50 earth-years. Then you only need 39.1 m/s², or about 4g, which is apparently something mere mortals can basically take.

So your time numbers aren't that unrealistic, the problem is of course to find an actual spaceship that can do this for 3 years nonstop, plus you should carefully plot your course (since you'd travel up to 4.6 ly in that time).

The real problem is propulsion: If you go by conventional rockets (or rather, a relativistic rocket) and assuming the best possible exhaust velocity, namely c and that you arrive back at Earth with mostly no rocket left (m_1=100 kg), you need a rocket with an initial weight of 1.8e359 kg, which slightly exceeds the mass of the observable universe... The circular travel vastly improves this (4.3e108 kg), but not remotely enough.

Summary: While the acceleration required is bearable, achieving it via conventional means of propulsion is impossible. You'd probably have to be very creative with thousands of Swing-by's (which would also influence the passage of time) in order to get along with realistic amounts of fuel, and at those high momenta you would probably severely influence the assisting celestial bodies. Sounds like a lot of havoc to merely travel into the future...

note I think I mixed up external and internal acceleration in the G-Force determination, the perceived force might actually be larger...

• Create answer! I was trying to figure out if reaching such a speed is realistic, but I'm no physicist :) in terms of fuel, yes I agree today's conventional fuel is not feasible. I was considering extremely fuel efficient solutions such as the Buzzard ramjet or other solutions mentioned in here: physics.stackexchange.com/questions/47893/… – crusarovid Jul 17 '15 at 22:22

Technically, yes, but probably not how you are thinking. A person in orbit around earth experiences time slightly different than someone on the earth's surface. The person in orbit will have aged slightly less. Here is a link to some experiments concerning time dilation: phys.org .

• Indeed Russian Cosmonaut Sergei Avdeyev has travelled 1/50 of a second into the future using this method having spent 2 years on Mir – colmde Mar 24 '15 at 22:33
• @colmde - I can't help but laugh when you put the numbers down like that - definitely not an efficient method, but does make you wonder which 1/50 of a second he skipped... – Brad Mar 25 '15 at 19:42

Another scenario I thought of is where an individual travels in space on a spaceship. After traveling for say, 3 years, he returns to earth and 100 years have passed on earth. Thereby he "traveled into the future".

GPS time is accurate enough to be affected by this, so they could be said to be moving at a rate other than exactly "one second per second", but only very slightly. This basically depends on how fast a spaceship you can build and how much fuel you can put on it.