Time Travel

[Bill the Butcher]

Forget what you remember from TV and film... we aren't talking about time machines that run on garbage or a vehicle with a chair and a million glowing buttons. Let's put theories, physics, and space into the topic... the best way to converse about it.

First things first, who here believes time travel is possible?
-Time travel to the future?
-Time travel to the past?
-Time travel in both directions?
What do you think?

One-way travel into the future is arguably possible given the phenomenon of time dilation based on velocity in the theory of special relativity as well as gravitational time dilation in the theory of general relativity. However, the laws of physics does not allow backwards time travel into the past.

Time dilation is the phenomenon whereby an observer finds that another's clock, which is physically identical to their own, is ticking at a slower rate as measured by their own clock.

http://en.wikipedia.org/wiki/Time_dilation

Time dilation is permitted by Albert Einstein's special and general theories of relativity. For example, a clock which is moving relative to the observer will be measured to run slow in that observer's rest frame; as a clock approaches the speed of light it will almost slow to a stop, although it can never quite reach light speed so it will never completely stop. For two clocks moving inertially (not accelerating) relative to one another, this effect is reciprocal, with each clock measuring the other to be ticking slower. However, the symmetry is broken if one clock accelerates, as in the twin paradox where one twin stays on Earth while the other travels into space, turns around (which involves acceleration), and returns—in this case both agree the traveling twin has aged less.

http://en.wikipedia.org/wiki/Time_travel#Time_dilation

The common paradox of time travel is the "grandfather paradox". It's a fairly simple paradox to understand: suppose a man traveled back in time and killed his biological grandfather before the latter met the traveller's grandmother. As a result, one of the traveller's parents (and by extension, the traveller himself) would never have been conceived.

http://en.wikipedia.org/wiki/Grandfather_paradox

Some people follow this paradox as the end-all be-all of the impossibility of backwards time travel. However, a number of possible ways of avoiding the paradox have been proposed, such as A) the idea that the timeline is fixed and unchangeable, or B) the idea that the time traveler will end up in a parallel timeline (parallel universe/dimension... kinda like at the end of the remake of Planet of the Apes), while the timeline in which the traveler was born remains independent. (Refer to Doc Brown in Back to the Future 2 drawing on his chalkboard a sklew in timeline A compared to timeline B.)

The use of cosmic strings, blackholes, and Wormholes and moving faster than the speed of light have been proposed ways of traveling backwards in time. Diagram of a wormhole:

http://en.wikipedia.org/wiki/Image:Worm3.jpg

Oh yeah, another thing that I like to think about (despite my belief that time travel is possible) is that if time travel was possible... you think we would've seen something happen recently or in the past, like a time traveller from the future. Or maybe we wouldn't have seen them at all? Perhaps in the future, there are invisibility cloaking devices on everything, and he/she/it could've been here, but we just didn't see them? It's an interesting thought.

[Ziner]

I find time travelling very possible. I just did it Saturday night. I was at a buddy's wedding had about 15 vodka and tonic's and woke up the next morning and apparently time travelled from about 8pm to 9 am the next morning

[rebelwithoutaclue]

Based on Einstein's field equations it IS possible, but highly improbable. A few ways it could theoretically happen, that are actually backed up by physics and not science fiction:

Building a machine that can use enough energy to stabilize a worm-hole, which is thought to connect a point in spacetime to another point in spacetime. Energy required is probably more than all the man-made energy we've ever produced.

If a machine is built on Earth, current theory says that you would turn it on and at any point afterwards you can go back in time, but only as far back as when the machine was turned on, essentially because before the machine was built (functional), "time didn't exist".

Will never happen like in Star Trek because that would require moving a particle with mass faster than the speed of light, which would require infinite energy (let alone the energy required to move a giant spaceship back in time).

[Mr. MacPhisto]

Will never happen like in Star Trek because that would require moving a particle with mass faster than the speed of light, which would require infinite energy (let alone the energy required to move a giant spaceship back in time).

Actually, we really don't know. We guess that it would require infinite energy but we actually don't know if that's the case. We've been wrong on things before, like believing that the speed of light is a constant when it is not truly one (light travels faster in a vacuum and does slow down through gas clouds and is affected by gravity).

I think it's unlikely that we'll ever discover the secrets of time travel. It may be possible but completely out of the grasp of our minds. The theories are interesting (multiverse theory, etc) and I'd be one that would love to go back in time just to witness a variety of events but I think it will always be speculation for us just as FTL travel might be. Just because we can't find a way to do something doesn't mean it's not possible.

[Bill the Butcher]

Just because we can't find a way to do something doesn't mean it's not possible.

Sadly, there are many people out there who believe the opposite.

[Mr. MacPhisto]

Sadly, there are many people out there who believe the opposite.

There are a lot of scientists in a variety of fields that are the same way.

I've done work in archaeology in the past and it's really amazing sometimes when you examine the assumptions made. Many of the social scientists will come to a conclusion based on the lack of evidence for something - often times they'll also use their own criteria for even determining that.

I recall a conversation I had with one of my professors, a renowned biblical archaeologist. A colleague of his had made a statement in a published book (one that he actually assigned to us) that Capernaum was lacking certain structures from the first century period and, thusly, it must not have been a wealthy community. My professor responded to that by telling me that they had essentially barrels and barrels of gold, silver, pearls, jewels, etc that they had found from that same period that his colleague failed to mention because he was so focused on using architecture of the time to prove his point that he omitted some very critical evidence.

Scientists, not social and physical, are just like everyone else. They have biases and will ignore evidence and be dishonest sometimes if it suits them. The same can go for time travel and other things in theoretical physics. As we delves into quantum mechanics the mathematics becomes more impossible to comprehend. Because of this I think you end up with some pretty whacky theories that are difficult to prove and some won't even attempt to prove it.

One issue is that so much in theoretical science is built on assumptions and sometimes those assumption are far from being proven. Take string theory as an example. Fascinating stuff but also a bit dodgy. The math is wonky and much of it is clearly forced.

[rebelwithoutaclue]

Actually, we really don't know. We guess that it would require infinite energy but we actually don't know if that's the case. We've been wrong on things before, like believing that the speed of light is a constant when it is not truly one (light travels faster in a vacuum and does slow down through gas clouds and is affected by gravity).

I see your point in us being wrong about many things before but we were wrong about those things because our minds couldn't even grasp anything different. We aren't really "guessing" here (unless you think Einstein's field equations are wrong) since we have a mathematical formula that proves time travel is possible under certain conditions except that those conditions require tremendous amounts of energy that aren't possible to replicate on Earth. Now this only applies to flying a spaceship back in time. Some of the other ways seem more plausible.

[Mr. MacPhisto]

I see your point in us being wrong about many things before but we were wrong about those things because our minds couldn't even grasp anything different. We aren't really "guessing" here (unless you think Einstein's field equations are wrong) since we have a mathematical formula that proves time travel is possible under certain conditions except that those conditions require tremendous amounts of energy that aren't possible to replicate on Earth. Now this only applies to flying a spaceship back in time. Some of the other ways seem more plausible.

Einstein's equations are based on assumptions that he made. They could be right. Fact is, we really are guessing until they can be proven absolutely by someone actually traveling in time.

Quite a bit of what we call science is nothing more than guess work. The age of the Earth? Guess work built on assumptions about geology that we cannot prove because no record of a witness exists, so we make assumptions and those assumptions actually have a lot of problems. Most of our dating techniques make massive assumptions and are based upon uniformitarianism, a concept that we see in our own time doesn't really hold true because of catastrophe. Carbon-14 doesn't always degrade at the same rate. In fact, different areas around the world degrade at different rates. K-Ar is very similar and even more iffy because some of the Carbon dating we use can be verified by historical accounts. K-Ar only gives us dates in the distant past that are based upon an assumption that has issues.

Take the Earth's magnetic field. If we assume that it has deteriorated at its current rate throughout history then the Earth would have been uninhabitable going back only many thousands of years, prior to recorded history. This is ignored and it is assumed that that was not the case, but the scientific establishment basically throws it out because it doesn't fit with their established timeline, even though their uniformitarian principles are applied to get the larger dates.

The point is that most of that kind of stuff is nothing more than guesswork. It's interesting to discuss but I think it is dishonest when presented as an absolute fact. The problem is that those scientists like to present it as fact or say something is proven when it really is not. It'd be great if they all actually prefaced a comment with "If our assumptions are correct".

Part of it stems from the human condition. We want solid answers and don't want to have to really on faith of any kind if we don't have to. Fact is that life is really all about faith in something. Sometimes it is blind faith or not even recognized as faith. People have a lot of blind faith in science that is certainly comparable to religious faith. As I said though, ultimately it all comes down to faith. Very little is verifiable except for what we can see and touch in the here and now. Much of science has become conjectural and the hard sciences that are much more verifiable, like chemistry, don't attract as much attention because they don't try to explain the human condition.

What were we talking about? Oh right, time travel. Sorry for the rant.

[rebelwithoutaclue]

Part of it stems from the human condition. We want solid answers and don't want to have to really on faith of any kind if we don't have to. Fact is that life is really all about faith in something. Sometimes it is blind faith or not even recognized as faith. People have a lot of blind faith in science that is certainly comparable to religious faith. As I said though, ultimately it all comes down to faith. Very little is verifiable except for what we can see and touch in the here and now. Much of science has become conjectural and the hard sciences that are much more verifiable, like chemistry, don't attract as much attention because they don't try to explain the human condition.

If we're comparing science and religion I'd call religion blind faith and science "less blind" faith. Science at least has observation and analysis so that the thing you are believing is based on something that anyone can see/do. But the main point that I got from your post is that we can never know anything for sure, which is true but basically meaningless. By your way of thinking everything in history before 130 years ago might not have existed since no one around today was there to experience it. It'd be sad to live your whole life by prefacing every moment thinking it might not be real. My senses tell me things about the world around me, the world that numerous geniuses far greater/smarter than I have already quantified. Throughout human history there have been countless observations that have been recorded and re-recorded so many times that it would be ignorant to think that things don't really happen that way. The day an apple falls up from a tree instead of down is the day I'll call all science a sham and that we know nothing. Short of that, with all other things being equal, the simplest answer is usually correct.

What were we talking about again, time travel? In relation to time travel this probably doesn't apply since modern astrophysics is such a new field and the observations and proofs have only been done by a few people, no where near enough to have any universal acceptable answers (obviously).

[Mr. MacPhisto]

If we're comparing science and religion I'd call religion blind faith and science "less blind" faith. Science at least has observation and analysis so that the thing you are believing is based on something that anyone can see/do. But the main point that I got from your post is that we can never know anything for sure, which is true but basically meaningless. By your way of thinking everything in history before 130 years ago might not have existed since no one around today was there to experience it. It'd be sad to live your whole life by prefacing every moment thinking it might not be real. My senses tell me things about the world around me, the world that numerous geniuses far greater/smarter than I have already quantified. Throughout human history there have been countless observations that have been recorded and re-recorded so many times that it would be ignorant to think that things don't really happen that way. The day an apple falls up from a tree instead of down is the day I'll call all science a sham and that we know nothing. Short of that, with all other things being equal, the simplest answer is usually correct.

What were we talking about again, time travel? In relation to time travel this probably doesn't apply since modern astrophysics is such a new field and the observations and proofs have only been done by a few people, no where near enough to have any universal acceptable answers (obviously).

Why the arbitrary 130 years date? I do think historical accounts play a role and are less about assumption.

I'd also call religion less of a blind faith. My faith is built on logic and an understanding of obvious truths. For instance, any clear thinking person would find it obvious that something finite must ultimately come from something infinite. Since energy and mass are, by the laws of physics, eternal, yet those laws don't account for some kind of creation or a time when all the energy and mass was put into the system.

Often we even ignore observation. There's a lot of "science" that completely ignores the law of entropy because that particular "science" doesn't work without it.

I don't live my whole life wondering whether things are real. I just realize how much faith runs everyone's lives. That's something that my observation tells me. I'm a historian and do trust historical documentation. In fact, I tend to trust it more than I do quite a bit of the natural history lying around that is manipulated by flawed scientific tests. I've found over the years that stratigraphic dating with reference to historical material is more accurate than C-14 dating of the same material. True, I have made some assumptions in coming to that conclusion, but if I have numerous ancient documents that indicate a certain type of pottery was made at a certain time and it is all found in the same stratigraphic layer then I'll generally trust that over the C-14 numbers that tend to bounce around a lot.

It's wise to understand how little one actually does know and realize how much is relied upon faith every day. I agree, some science is fairly well grounded in reality. Chemistry and Newtonian physics, for instance. Einstein's relativity and the newer quantum theories are much less grounded in observation and reproducibility. Biology is another area that is split. We do have observational biology, like how an organ functions or a specific animal functions, etc. We also have observational data on adaptation, often called micro evolution, but no observation on any macro evolution or even fossil records of any transitions.

Part of the problem is that the word "theory" is thrown around to easily. A theory comes after a hypothesis has been refined and eventually repeatedly proven in a controlled environment. Much of what scientists have now called theories nowadays are nothing more than hypotheses that have not been and often cannot be proven or repeatedly demonstrated. We might be able to demonstrate a surrounding concept without actually proving the general hypothesis.

There's a lot of arrogance in scientific circles about the supremacy of science these days and a lot of dogma. Legitimate scientists that disagree with the views of those that peer review publications or make decisions about grants are shunned, mocked, and often cast aside. This is actually very unscientific and more in line with how the medieval church would suppress ideas. The new religious dogma is often veiled as science when it really has little to do with the pursuits of true science.

Science is the pursuit of truth because that's what the word means. Often too many are obsessed with proving themselves right that they ignore anything that could contradict a pet hypothesis or they ignore things that they are dead set against.

[rebelwithoutaclue]

Why the arbitrary 130 years date?

Roughly the age of the oldest living person + about 10-20 years to make sure that no one that's alive now was alive then. Basically if I woulda used a round number like 100 someone would have come and said people live longer than that so I was trying to cover the bases for my inane supposition.

[Mr. MacPhisto]

Roughly the age of the oldest living person + about 10-20 years to make sure that no one that's alive now was alive then. Basically if I woulda used a round number like 100 someone would have come and said people live longer than that so I was trying to cover the bases for my inane supposition.

Back to the issue of time, one of the fascinating aspects of the modern era is the amount of documentation historically. Think of the film, newspaper archives, history books, etc all pertaining to WWI. The movies of the period, etc. Greater documentation makes the allure of going back in time to those periods far less appealing unless you want to live in that time or attempt to change history. Of course, the changing history aspect is always paradoxical. If you change it then there's no impetus for you to go back in the first place, leaving it unchanged and making you wish to change it again.

There've been some theories proposed that dictate that we wouldn't be able to change things. That the laws of space and time would only allow us to observe. That opens another can of worms as well. Do space and time branch at each decision that each person makes? Is there an alternate reality where I decided to go back to bed for an extra hour this morning instead of going ice skating? A reality where Hitler wasn't born? Or is there just the one reality and one timeline that continues forward?

It's difficult to know if we can travel through time if we don't truly understand the nature of time other than its passing as we move forward.

[osucrazy18]

definatly could be possible

so heres another question what would you guys look at first, besides blowing john elways head off

[Bill the Butcher]

There've been some theories proposed that dictate that we wouldn't be able to change things. That the laws of space and time would only allow us to observe. That opens another can of worms as well. Do space and time branch at each decision that each person makes? Is there an alternate reality where I decided to go back to bed for an extra hour this morning instead of going ice skating? A reality where Hitler wasn't born? Or is there just the one reality and one timeline that continues forward?

As I mentioned in the opening post, people usually use that paradox to state the impossibility of time travel. But then there are other guesses stating that the original timeline is skewed, creating another "dimension"... ya know... like alternate dimensions or whatever. See: Back to the Future Part II

MacPhisto... you ever hear about the topic on dimensions? Like the 1st, 2nd, 3rd, and 4th dimensions? I haven't read into anything yet, but my cousin was telling me about it, trying his best to explain it, and he says that we're currently in the 3rd dimension; said something like "we can walk around on a plane" and it's the present or something like that. And then he said that the 4th dimension is actual time travel... moving from point to point along a timeline.

[rebelwithoutaclue]

There've been some theories proposed that dictate that we wouldn't be able to change things. That the laws of space and time would only allow us to observe. That opens another can of worms as well. Do space and time branch at each decision that each person makes? Is there an alternate reality where I decided to go back to bed for an extra hour this morning instead of going ice skating? A reality where Hitler wasn't born? Or is there just the one reality and one timeline that continues forward?

As I mentioned in the opening post, people usually use that paradox to state the impossibility of time travel. But then there are other guesses stating that the original timeline is skewed, creating another "dimension"... ya know... like alternate dimensions or whatever. See: Back to the Future Part II

MacPhisto... you ever hear about the topic on dimensions? Like the 1st, 2nd, 3rd, and 4th dimensions? I haven't read into anything yet, but my cousin was telling me about it, trying his best to explain it, and he says that we're currently in the 3rd dimension; said something like "we can walk around on a plane" and it's the present or something like that. And then he said that the 4th dimension is actual time travel... moving from point to point along a timeline.

The currently accepted theory is that we live in 4 dimensions (x,y,z axis'), with spacetime (1 thing) being the 4th dimension. Time travel already happens, to an extent. Astronauts experience a form of time travel when they accelerate into space as time actually passes more slowly for them because of how fast they are travelling. On the other end, objects with incredible amounts of mass (galaxies, black holes) and therefore incredible amounts of gravity also cause time to pass more slowly. Superstring theory (M-theory) is in the infant phases of trying to explain the connection between general relativity (laws that govern the motion of large objects like stars and galaxies) and quantum mechanics (laws that govern the motion of atomic world) to create a theory of everything (grand unified theory). That theory states that instead of particles the universe is made up of strings (10^20 times smaller than a proton) that vibrate on certain wavelengths in 11 dimensions.

[General]

There've been some theories proposed that dictate that we wouldn't be able to change things. That the laws of space and time would only allow us to observe. That opens another can of worms as well. Do space and time branch at each decision that each person makes? Is there an alternate reality where I decided to go back to bed for an extra hour this morning instead of going ice skating? A reality where Hitler wasn't born? Or is there just the one reality and one timeline that continues forward?

As I mentioned in the opening post, people usually use that paradox to state the impossibility of time travel. But then there are other guesses stating that the original timeline is skewed, creating another "dimension"... ya know... like alternate dimensions or whatever. See: Back to the Future Part II

MacPhisto... you ever hear about the topic on dimensions? Like the 1st, 2nd, 3rd, and 4th dimensions? I haven't read into anything yet, but my cousin was telling me about it, trying his best to explain it, and he says that we're currently in the 3rd dimension; said something like "we can walk around on a plane" and it's the present or something like that. And then he said that the 4th dimension is actual time travel... moving from point to point along a timeline.

The currently accepted theory is that we live in 4 dimensions (x,y,z axis'), with spacetime (1 thing) being the 4th dimension. Time travel already happens, to an extent. Astronauts experience a form of time travel when they accelerate into space as time actually passes more slowly for them because of how fast they are travelling. On the other end, objects with incredible amounts of mass (galaxies, black holes) and therefore incredible amounts of gravity also cause time to pass more slowly. Superstring theory (M-theory) is in the infant phases of trying to explain the connection between general relativity (laws that govern the motion of large objects like stars and galaxies) and quantum mechanics (laws that govern the motion of atomic world) to create a theory of everything (grand unified theory). That theory states that instead of particles the universe is made up of strings (10^20 times smaller than a proton) that vibrate on certain wavelengths in 11 dimensions.

Holy Crap!

[Mr. MacPhisto]

The currently accepted theory is that we live in 4 dimensions (x,y,z axis'), with spacetime (1 thing) being the 4th dimension. Time travel already happens, to an extent. Astronauts experience a form of time travel when they accelerate into space as time actually passes more slowly for them because of how fast they are travelling. On the other end, objects with incredible amounts of mass (galaxies, black holes) and therefore incredible amounts of gravity also cause time to pass more slowly. Superstring theory (M-theory) is in the infant phases of trying to explain the connection between general relativity (laws that govern the motion of large objects like stars and galaxies) and quantum mechanics (laws that govern the motion of atomic world) to create a theory of everything (grand unified theory). That theory states that instead of particles the universe is made up of strings (10^20 times smaller than a proton) that vibrate on certain wavelengths in 11 dimensions.

There are lots of issues with string theory and much debate in the physics community. There are a lot of physicists that don't believe that string theory even is a part of physics and nothing in string theory has been able to verified through experimentation or even prediction. Issues also exist with general relativity (as you mentioned).

String theory is an interesting postulation but one that may be superceded by something else in the future.

For Bill. There are a lot of different postulates out there in regards to time travel and paradoxes. On idea is the multi-dimensional idea. Some have suggested that it is impossible or too difficult to travel backwards in time but it is possible to travel into an extremely similar dimension. Changes in that dimension would not affect your own dimension, keeping the timeline from changing.

It can get pretty confusing trying to follow the different time travel theories and different variations of hypothetical physics.

[Bill the Butcher]

Time travel already happens, to an extent. Astronauts experience a form of time travel when they accelerate into space as time actually passes more slowly for them because of how fast they are travelling.

Yeah, that, to me, is so interesting to think about. Somebody should be born on Earth, but live in a space station all their lives, and then come back down to Earth when they're like... 70.

That just reminds me of Spielberg's Close Encounters when the extraterrestrials bring back all of the humans they abducted to study, and the people range from like 17th century Dutch women to the WWII fighter pilots... and they haven't aged one bit. And one of my fav lines of the film after people realize these abductees haven't aged...

Man 1: Einstein was right...

Man 2: Einstein was probably one of them (meaning an extraterrestrial).

[tbone]

I have nothing productive to contribute other than this...

[youtube]http://www.youtube.com/watch?v=iGlrobvb-ao[/youtube]

[ThisIsNat]

so heres another question what would you guys look at first, besides blowing john elways head off

If I could go back in time...I would somehow get a message to Grover to TAKE MESA OUT before he blew Game 7!

[Mr. MacPhisto]

If I could go back in time...I would somehow get a message to Grover to TAKE MESA OUT before he blew Game 7!

Or maybe a message to not even put Mesa in. I still say he shoulda gone with Nagy, though Chuck could get nervous.

I'd also said a message back to Webster Slaughter and tell him to be sure to block Castille on any Byner running play.

I'd also send a message to Marty and tell him to play to win in 86 and not to play the damn prevent.

[Bayou Tribe]

The currently accepted theory is that we live in 4 dimensions (x,y,z axis'), with spacetime (1 thing) being the 4th dimension. Time travel already happens, to an extent. Astronauts experience a form of time travel when they accelerate into space as time actually passes more slowly for them because of how fast they are travelling. On the other end, objects with incredible amounts of mass (galaxies, black holes) and therefore incredible amounts of gravity also cause time to pass more slowly. Superstring theory (M-theory) is in the infant phases of trying to explain the connection between general relativity (laws that govern the motion of large objects like stars and galaxies) and quantum mechanics (laws that govern the motion of atomic world) to create a theory of everything (grand unified theory). That theory states that instead of particles the universe is made up of strings (10^20 times smaller than a proton) that vibrate on certain wavelengths in 11 dimensions.

Recent research has shown the empirical evidence for globalization of corporate innovation is very limited, and as a corollary, the market for technologies is shrinking.

As a world leader, it is important for America to provide systematic research grants for our scientists. I believe there will always be a need for us to have a well-articulated innovation with emphasis on human resource development. Thank you.

[rebelwithoutaclue]

The currently accepted theory is that we live in 4 dimensions (x,y,z axis'), with spacetime (1 thing) being the 4th dimension. Time travel already happens, to an extent. Astronauts experience a form of time travel when they accelerate into space as time actually passes more slowly for them because of how fast they are travelling. On the other end, objects with incredible amounts of mass (galaxies, black holes) and therefore incredible amounts of gravity also cause time to pass more slowly. Superstring theory (M-theory) is in the infant phases of trying to explain the connection between general relativity (laws that govern the motion of large objects like stars and galaxies) and quantum mechanics (laws that govern the motion of atomic world) to create a theory of everything (grand unified theory). That theory states that instead of particles the universe is made up of strings (10^20 times smaller than a proton) that vibrate on certain wavelengths in 11 dimensions.

Recent research has shown the empirical evidence for globalization of corporate innovation is very limited, and as a corollary, the market for technologies is shrinking.

As a world leader, it is important for America to provide systematic research grants for our scientists. I believe there will always be a need for us to have a well-articulated innovation with emphasis on human resource development. Thank you.

Pure gold.