Sagan on Time Travel

Sagan on Time Travel

www.pbs.org

The reason this is connected with time travel is because another consequence of special relativity is that time, as measured by the speeding space traveler, slows down compared to time as measured by a friend left home on Earth. This is sometimes described as the "twin paradox": two identical twins, one of whom goes off on a voyage close to the speed of light, and the other one stays home. When the space-traveling twin returns home, he or she has aged only a little, while the twin who has remained at home has aged at the regular pace. So we have two identical twins who may be decades apart i

(visit the link for the full news article)

well I just had a thought i would like some input on... today's alien sightings are usually described as a round metal flying objects with lights...and im an addict to the show Ancient Aliens, well it shows ancient paintings and carvings and sculptors of the exact same aircrafts visiting earth.

My question is- why havent their aircrafts changed? on earth we continually advance our technology. so why haven't they? so i thought of something. our time is at a set pace. but in space, is it possible that there are pockets that the actual pace of time is slowed?

the article i referenced to isnt really realative, i couldnt find an article about what i was thinking. but it talks about the speed of light being realative to time. maybe there is a planet out there that travels close to the speed of light, and the aliens are on it. they would be stuck at a slowed down version of time, and to them, we would be in fast forward.

so any thoughts? maybe this being snowed in for two weeks has gone to my head.

www.pbs.org
(visit the link for the full news article)

Originally posted by boomonsta
My question is- why havent their aircrafts changed? on earth we continually advance our technology. so why haven't they?

Fascinating question.

Aerospacecraft on Earth have undergone many generations of advancement since the Wrights first flew at Kitty Hawk in 1903. But the upward curve of technological advancement is beginning to flatten. By the time a civilization attains interstellar/time travel capability, it may be that optimized design solutions exist and are 'locked in'.

An Earthly example is the Lycoming aircraft piston engine O-320. It was FAA certified on 28 July 1953 to CAR 13 effective 5 March 1952.

It is still sold in new aircraft in 2011. The design was 'locked-in', effectively frozen in time.

So advanced craft may be 'standardized' either by the laws of physics or by some 'authority'.

On this post
www.abovetopsecret.com...
They found information about a project to travel to other solar systems.
They said about building a tube of some kind of energy.
Then travelling up the tube at near the speed of light.
When they get there it would be back in time!!!!
So if they built a second one and came back.
It would be 6000 years in the past?
I will try to find it.
but this would mean the came from the futre?

I found it
www.osti.gov...
"We analyze difficulties with proposals for hyper-fast interstellar travel via modifying the spacetime geometry, using as illustrations the Alcubierre warp drive and the Krasnikov tube. As it is easy to see, no violations of local causality or any other known physical principles are involved as far as motion of spacecrafts is concerned. However, the generation and support of the appropriate spacetime geometry configurations does create problems, the most significant of which are a violation of the weak energy condition, a violation of local causality, and a violation of the global causality protection. The violation of the chronology protection is the most serious of them as it opens a possibility of time travel. We trace the origin of the difficulties to the classical nature of the gravity field. This strongly indicates that hyper-fast interstellar travel should be transferred to the realm of a fully quantized gravitational theory. We outline an approach to further the research in this direction."

top right of page click PDF and down load all info.
how do you get back to your own time?
go to sleep for 6000 years?

Originally posted by buddha
how do you get back to your own time?
go to sleep for 6000 years?

A Double-Barrel Krasnikov Tube could get you back just after you left-
If Krasnikov Tubes could ever exist...

reply to post by boomonsta


I saw an article talking about time travel.. One of the theories suggested was the "alien" visitation we see are Humans from the far future. Speculation abounds that they are trying to change history to correct something that happens in their own time.

The other is they learned the lesson that you shouldnt tamper with human genetics to improve people the hard way. Future humans coming back in time to get non mutated DNA to save their time.

Originally posted by boomonsta. today's alien sightings are usually described as a round metal flying objects with lights...

They are? By whom? Every UFO report I read is a little bit different, and I'm not sure if any UFO is alien, what makes you think the UFOs are alien? And cameras are everywhere. Has anyone ever taken a picture of one of these "round metal flying objects with lights"? If so, I'd like to see it, please post it.

My question is- why havent their aircrafts changed?

I'm not sure the ancient art you refer to shows aircraft. Maybe post a sample you think might be an aircraft, could it have an alternate explanation? I see many representations of the sun and the moon that people think look like aircraft, but they're drawings of the sun and the moon in a special style of art, not aircraft.

Now if your premise was true that "their craft" haven't changed (and I've seen nothing to convince me it's true), one simple explanation could be that they are time travelers. But I don't have any particular reason to believe that.

I've watched the show ancient aliens too (lots of them airing lately it seems), and it's all very speculative. There are lots of other explanations besides the ones they offer on that show.

I don't understand how traveling at the speed of light can alter time... Wouldn't it just mean you could get somewhere faster because you were traveling faster? I think time travel is an interesting subject, but I don't think it could ever be real. At least not with the speed of light theory that seems to be the most common. Hear me out...
The op mentions two identical twins that could end up decades apart in age if one traveled somewhere and back at the speed of light. Let's take the same twins but on a smaller, more practical scale. Let's say the twins were both going to travel from washington state to california. One will travel by plane which will take approximately 4 hours. The other will drive which will take about two days if the driver stops to sleep. So twin number two finally arrives in california where twin number one has been waiting for two days. This does not mean that twin number two is now two days older than number one. One just traveled at a faster speed, but they still aged the same amount.
Now wouldn't logic suggest that the same would happen at the speed of light? The one traveling would still age as much as the other waiting on earth. No matter how fast he was traveling, he would still be gone the same amount of earth time that the other was on earth waiting. He would just be moving really fast...

reply to post by stealthXninja


You're misunderstanding the concept of time dilation, described by relativity. There's two different forms of time dilation that can work together; Gravitational, and relative velocity. For time dilation, in relative velocity, to have noticeable effects, you have to be going incredibly fast (like fractions of light speed fast). Of course there is still time dilation present at less impressive speeds but good luck noticing the insanely small difference.

Time dilation observed at 10 m/s

reply to post by Stuffed


I read the article you linked me to. I honestly don't see how that is proof of time travel. It is probably a little over my head, but as much as I would love to believe it's possible, I just don't see it ever happening. In all sincerity, thank you for the information. I will dig further into time dilation on my own before I form an opinion about all this. My imagination wants to believe that there is merit to all of this, and that time travel is possible, but my logic is telling me otherwise.

Originally posted by stealthXninja
I will dig further into time dilation on my own before I form an opinion about all this. My imagination wants to believe that there is merit to all of this, and that time travel is possible, but my logic is telling me otherwise.

Don't take this personally, but your opinion and my opinion on this topic don't really matter, because it's been proven with not only GPS but also by a number of other experiments:

The time dilation effect has been measured and verified using the GPS

The effect of gravitational frequency shift on the GPS due to general relativity is that a clock closer to a massive object will be slower than a clock farther away. Applied to the GPS, the receivers are much closer to Earth than the satellites, causing the GPS clocks to be faster by a factor of 5×10^(-10), or about 45.9 μs/day. This gravitational frequency shift is noticeable.

So if you've ever seen GPS working, you've already seen proof of time travel, because if we didn't compensate for the time travel effect, the GPS wouldn't work, or it might get you to the right city, but it wouldn't be accurate enough to get you to an address within the city.

There are some caveats though:
You can only travel into the future, not the past. It's one-way only.
And it's both possible and impossible with current technology.

What it's possible to do is to make such small amounts of time travel occur that we need clocks as accurate as those used for GPS to measure the small effect. Without such accurate clocks we wouldn't even notice what we currently can do time travel wise.

We can accelerate subatomic particles in the LHC to near light speed and if you wanted to, you could send a proton a year into the future in the LHC, just spin it around at near the speed of light for a year, and only a day would go by for the proton. (actually I think it's only half a day for the proton going at .999999c or the 99.9999% the speed of light). The topic is discussed here: scienceforums.com...

Too bad the proton can't come back and tell us how only 12 hours went by for it whole a year seemed to go by to us.

Which brings us to the currently impossible but theoretically possible part: We don't know how to accelerate a human to anywhere near these speeds to have a significant time travel effect. The closest we could do with our current technology would be to go in a close orbit of the sun where the sun's gravity would have a similar effect to traveling fast, but it still wouldn't slow down time all that much. To really slow down time a lot, you'd need to orbit a black hole. While it's remotely possible our current knowledge could get you into orbit around a black hole just outside the event horizon, I'm less certain if you'd be able to escape the black hole's gravity.

Furthermore the only rocket capable of doing a mission like this, that I know of, would be something like Project Orion which will probably never be built since it's powered by atomic bombs and we're trying to cut back on those. Conventional rocket technology just wouldn't get you to a black hole and back.

Hopefully some breakthrough in the future will give us an advanced propulsion technology that might get us to the speed needed, or get someone to a black hole orbit and back, but I suspect it won't be anytime soon.

reply to post by Arbitrageur


I like to think some form of an evacuated tunnel mag lev train traveling on a huge circuit across the planet could accelerate up to some amazing speeds for noticeable time dilation.

Now how do we go about building one so i can take a trip to the future? hmmm

Originally posted by boomonsta

Sagan on Time Travel

www.pbs.org

The reason this is connected with time travel is because another consequence of special relativity is that time, as measured by the speeding space traveler, slows down compared to time as measured by a friend left home on Earth. This is sometimes described as the "twin paradox": two identical twins, one of whom goes off on a voyage close to the speed of light, and the other one stays home. When the space-traveling twin returns home, he or she has aged only a little, while the twin who has remained at home has aged at the regular pace. So we have two identical twins who may be decades apart i

(visit the link for the full news article)

Not having a pop at you , because I know this is the generaly held few of space/time.
I personally can't get this to add up. As I always think of time as more or less constant.
Take away the science and you are left with this hypothetical statement. You can all laugh but here it is.

Astronaught leaves distant system lets say 100 light years distant. He is in a craft that can traverse this space ~(between distant syatem and our own), in three hours.
His twin is unaware of his departure from the distant system. The astronaught arrives home. Three hours have passed for both people. Seems highly doubtfull that the astronaught would have gotten older.
I do understand the theory that time passess slower. I just don't think it will pan out in reality

Originally posted by Stuffed
noticeable time dilation.

It really depends on how you define noticeable. Our clocks are already accurate enough to measure the time dilation from existing high speed trains.

What I didn't go into in my last post was the energy required to accelerate to relativistic speeds. The LHC uses about a million dollars a month in electricity to accelerate a few protons or subatomic particles.

A 70kg person has a mass about 4x10^28 times greater than a proton.

So figure the LHC accelerates multiple protons and that a train has significantly more mass than a person, without getting too picky about correcting for excatly how many protons the LHC accelerates or exactly how much heavier a train is than a person, just for a ballpark figure, multiply a million dollars a month by 4x10^28 and what kind of monthly electric bill do we get?

How many dollars is that? And can we make that kind of energy at any cost?

For example, how does that amount of energy compare with the total output of the sun?

If you start doing the math on the energy requirements you can see there are bigger problems than how to build the train.

Originally posted by rigel4
You can all laugh but here it is.

Astronaught leaves distant system lets say 100 light years distant. He is in a craft that can traverse this space ~(between distant syatem and our own), in three hours.
His twin is unaware of his departure from the distant system. The astronaught arrives home. Three hours have passed for both people.

Three hours haven't passed for both people.

You have to say which frame of reference you're measuring the three hours in. If it's three hours on the spaceship, then depending on how fast he was going, there might have been 50 years go by for his twin during those three hours.

And there's no reason to laugh at your lack of understanding, nobody we know of in the entire history of civilization figured this out before Einstein. And it's still a little confusing for many people. It's fine to say you don't understand it, there's no shame in that.

But it's kind of ignorant to deny it when all the brilliant scientists who have confirmed this with experiments have given us no reason to doubt it.

Thanks for youe responce , I have Little knowledge of the true maths involved for tim dialation, but it just seems to be such an odd concept to me. However I do acknowledge that the scientists are almost certainly right.
This highlights another point though, in relation to ET travel throughout the universe.
If these ET's are able to navigate the universe in an Inter Galactic way, then these travellers will never see their friends or family again,due to the time that will pass while they are away on their journey's so to speak.
Also how does this little thought work out.

Say you have an et ready to take flight from the Andromeda galaxy towards earth! Then say we set the date , lets say May the 12th, or what ever their equivelent is! Their Journey is going to take them one week.
Before i go any further, Is it right to assume that both peoples are living in the same space time frame?
So the et sets off, will it be years and years later when the et lands on earth. for example 50 years later.
and then he returns top his point of origin. 100 Years. seems to make Intergalatic space travel pointless for the civilisation doing the exploring. Every journey measured in hundreds of years for the home planet.