Time Travel
Time travel is best described as being able to move between two points in time much the way a person moves between two points in space. Time travel is a concept most often seen in science fiction. Questions about time travel can be directed here.
Asked in Physics, Scientists, Quantum Mechanics, Time Travel
What type of physicist studies time travel?

Theoretical physicist more than likely.
As far as time travel I fear physicists have already discovered
what is worth to be know. Travel towards future is in principle
possible. It is sufficient to move with a speed near the light
speed with respect to the starting inertial reference (the earth
for one of us).
The relativistic phenomenon of time compression provoke the time
to pass much slower for the traveler with respect to the persons
remaining in the "fixed" reference.
When the traveler returns in the initial reference (the earth in
our example) he effectively traveled towards the future.
Unfortunately, travel towards the past is effectively impossible
due to the causal nature of the laws of physics. As a matter of
fact, reversing the time in only one phenomenon (the travel of our
traveler in this case) violate the essential law of relativity that
causal order has to survive between events happening in the same
point of the space. Thus it is simply impossible.
(look, I'm not going to retype his entire response but: e-mc^2
thus a particle with a negative mass will go at a negative velocity
and thus backwards in time. such particles are thought to be
possible (at least not counted out yet) there are also a million
other ways that intelligent forces can bypass naturally unbreakable
laws such as wormhole's, however improbable they may be, given
infinite time and flexible enough conditions anything is possible.
so go ahead and become a theoretical physicist and prove this guy
wrong.)
This renders traveling to future quite unattractive: It is
impossible to return from such a travel.
Asked in Baseball, Cincinnati Reds, Time Travel
What is the time travel book about the Cincinnati Reds?

I just happen to be a huge Reds fan, an Aaron Boone fan, and an
Adam Dunn fan.
Anyway, enough about me. The book is "If I Never Get Back" by
Darryl Brock. The copyright date is 1989.
Buy it; it's a good one.
Answer
There's also a sequel called "Two in the Field." I really
enjoyed them both, and I'm not even a big Reds fan. There's some
great history and they're a quick, fun read.
Asked in Professor Layton and the Unwound Future, Time Travel
What is the answer for Puzzle 97 Professor Layton's Last Time travel?

Professor Layton and the last time travel has now been renamed
Professor Layton and the Unwound Future.
Professor Layton 3, Professor Layton and the Unwound
Future, has a confirmed release date of 20 September 2010 for
North America. Expect a similar release date for Europe
The Latest update for the release of the Unwound Future in the
UK is Early October 2010.
With this information in mind..can't answer puzzle 97 as I
haven't seen the puzzle yet?
Asked in Santa Fe Trail, Time Travel
What was the record time travel to Santa Fe trail?

Francois-Xavier Aubry, a merchant trader, holds the uncontested
record of traveling an seven hundred and eighty mile trip from
Santa Fe to Independence in five days, 16 hours on horseback from
September 12 to September 17, 1848. 190 miles a day.
He broke six horses during the ride, walked twenty miles, slept
two and a half hours and ate only six meals. Alexander Majors was
the only man to leave an eye-witness account of Aubry's famous
ride.
Aubry's scheme of placing horses at stations along the way would
be the inspiration for what became known as The Pony Express.
Asked in Inventions, Drawing, Benjamin Franklin, Time Travel
How do you draw a time machine?

Time 苹果彩票 do not exist, therefor drawing anything and
claiming it is a time machine will be fine. Time travel is very
likely impossible, so making something up might actually be more
accurate than basing your idea on a theory which will later be said
to have no possibility of working.
Here's an idea to get you started see the Related Links
Asked in Inventions, Physics, Time Travel
What is needed for time-travel?

An infinitely long rotating cylinder. [cf. Frank J. Tipler's
1974 paper "Rotating Cylinders and the Possibility of Global
Causality Violation", which shows that closed timelike curves are
mathematically possible in the vicinity of such an object.] Barring
that, you're pretty much out of luck, unless you just mean "into
the future at one second per second," in which case a cardboard box
will work fine. Being in an accelerating frame causes time to slow
down for you relative to an observer in a non-accelerating frame,
which could be considered a form of time travel. It still won't
allow you to go backward in time, so in science fiction terms it's
more like "suspended animation" than "time travel."
Asked in Inventions, Physics, Time, Time Travel
Will time travel ever become a reality?

Answer:
In Metaphysics: Yes, time travel already is a reality. If time
travel were not a reality, how then did we get suspended here in
this temporal dimension of time and space? Time exists as a polar
opposite to eternity, an opposite and equal reaction to time. This
is evident when we try to measure the immeasurable universe.
Time travel in our perception would imply rifts in the
space-time continuum, causing a paradox, much like that seen in the
movies "Back to the Future" and "Minority Report". Time travel is a
reality according to Einstein's theory of relativity, where the
faster an object travels, the slower time goes. Simply put, this is
only possible with exponential proportions of speed, resulting in
an explosive force that causes the matter traveling to turn into
energy at the speed of light squared--this is to say that matter is
what is traveling through time and space.
If time travel ever became a reality for people, wouldn't we
already known it by the rifts being caused? Let's say 1,000 years
from now someone comes back to this time or to a time before this;
we certainly would have historical records of the person that
traveled through time; because they may even be pictured or written
in history books!
In the Bible: Apparently, time travel must be possible in order
for the Bible to stand true, because the religious leaders said,
"We are the children of Abraham." And Jesus responded, "I tell you
the truth, before Abraham was, I AM." In a manner that truly defies
space and time. In this case, this man is, was, and will always be
the timeless man who defies the laws of nature; also, in order for
people to see the future and write it down as prophecy, time travel
must therefore be possible for this to work.
Changing the events of prophecy, such as Nineveh with Jonah
predicting their doom, is also apparent. This city turned to God
and the prophecy of doom was taken back, and they were forgiven.
This idea gives us a paradox of what would have happened had they
not turned to God and the city was destroyed; certainly some people
alive today would have then not been born! Time travel would
therefore be too dangerous for us humans to play with.
In Physics: It is an observation that two watches synched to
exactly the same time, will show variations to the thousandth of a
second when one watch is sent with a pilot at incredible speeds for
a set duration on a fighter jet. However, this is barely measurable
or even notable in our standards of "time." Nevertheless, if you
had a hypothetical time machine, you could travel at a great speed
and come back to earth thousands of years later, and only minutes
would have passed in your relative dimension of "time." (But you'd
have to travel precisely to the location earth would be in those
thousands of years later... since earth is traveling through space!
It's a long shot).
Einstein proved with his theory of relativity that time travel
is possible, but it's only scientifically proven to be able to
travel forward in time.
In conclusion, the only historical evidence of significant time
travel is recorded in the Bible, since Jesus must have that power
in order to be who he claimed to be--and in order for the prophets
to obtain knowledge of the future to precision. This brings many
questions to mind about paradoxes and destiny.
In the television series "Heroes", Hiro can travel through time
and space, even stop time--this is an interesting concept for those
who wish to change the past or see what the future holds.
Answer:
Answer1, two parts:
a) Time travel into the past probably never will be, but if it
does happen, it will be only possible to "watch", and not interact
or change things. Although this has not yet been proven, there are
plenty of logical paradoxes that have been thrown up by time travel
thought experiments that should convince us that this is the
case.
b) Time travel into the future is possible now. Travelling
through space at high speeds means you also travel through time as
well, although you only move forwards in time by small amounts
unless your speed approaches that of light. The astronauts that
went to the moon travelled forwards in time by a few seconds, i.e.
the atomic clocks they took with them slowed by a few seconds, and
the astronauts aged a few seconds less than they would have on
earth.
The answer 2 below is not incorrect (and this answer does not
contradict it) - it's just that the further forwards in time you
want to go and the faster you want to get to that future, time both
get exponentially more difficult and expensive, because the power
required gets exponentially great the faster in space you go
because your mass increases exponentially towards infinity. If a
cheap source of power is found to propel an ordinary space ship
towards light speed, it would take a long time to get near to light
speed, then time travel forwards will become commonplace.
Answer 2: No, TIME TRAVEL IS NOT POSSIBLE.
According to Einstein, time travel is not possible. We know that
E=M(C*C). That is Energy = Mass into square the speed of light in
vacuum speed of light in vacuum.
Suppose we invent a machine for time travel and as we reach the
speed of light, think of the energy needed to move the machine
forward.
i.e.: E=M(C*C)
As the speed increases, the energy required to move the machine
forward also increases and it is directly proportional to the fuel
required as we near the speed of light; the energy required becomes
nearly infinity and the fuel required to push the machine forward
also nears infinity. But, the resources available right now in
finite, so logically, time travel is not possible.
Answer 3: Food for thought.
I recall news announcements a few years back about a spaceship
that was being built. It was past the theory of warping space to be
able to travel to Mars, I think, in only hours. I seem to recall it
was a European country苹果彩票?. If true perhaps this will mean time travel
is indeed likely.
There was an article on newscientist.com that described this,
but has now been removed it seems. It was based on something called
a Z particle. And it is USA not Europe sorry.
After all, what man dreams today is tomorrows
reality.<br><p>I think we all are travellers in time.
Time and space, as I see it are being created at the border of the
known universe. The bigger the universe becomes, the more space is
created. In order to travel through space time is required. We
think of speed as distance per time. I would like to turn this
upside down and make time per distance of it. Now if one would like
to travel faster than time, one would have to travel at less than
zero seconds per distance! This implicates back in time. As E
equals MC square, the energy added to increase speed would be
converted to mass. I don't think time travelling is
practicable.
The answer above is practical. Talking more, it is actually
possible to travel time. Relativity claims that time is another
dimension, so like any other dimension it is possible to break the
barrier of time too. The theory states that anything faster than
light can travel time. But again the problem is the theory itself.
It states (by equation E=MC2) that as the speed tends to increase
the mass required to keep the speed increases and proportionately
the energy required to power the body too increases. Thus by the
speed of light the mass turns infinite and thus the energy turns
infinite too. It is impossible to achieve infinite energy thus it
is impossible to travel time. Ha, ha, ha, what a catch to the
theory right. But the law doesn't stop using Tachyons which always
travel faster than light. But Tachyons can only be used for
information.
No it can not be done because it passes on and that is just the
way it goes.
Asked in Physics, Stephen Hawking, Time Travel
Do you guys think time travel is possible?

Yes it is possible. If you orbit a black hole a bit away from
the event horizon in the speed of light then your movement in the
time axis will be drastically slowed down with respect to the rest
of the universe. Suppose you keep doing this for about a week and
return to Earth. You would be baffled to see that the earth has
probably aged a 1000 years or even more. Or maybe there is no Earth
to return to.
---
Yes, it is possible...but only if we can build a machine that
can accelerate and reach the speed of almost the speed of light
(the cosmic speed limit)...unfortunately, such a technology is
still a long shot as people, enterprises, and even the governments
are focusing on doing something else.
Asked in Astronomy, Black Holes, Astrophysics, Time Travel
Who can time travel in a black hole?

From what I've heard and read about the black hole, I don't
believe anyone can enter a black hole and live. From what I've
read, it sounds like you would be compressed. It would be like
being crushed slowly without being touched. I'm just wondering if
we can travel underneath it. If so, then we would know for sure it
leads to another galaxy. It would be proof that time and space can
be "torn" to go somewhere else. (Aside: You are only
compressed in the relativistic dimension of travel. As you approach
the speed of light you get less thick to an outside observer. To
you, the traveler, everything is just fine.)
Time doesn't really exist. It's merely a concept that exists
because our lives eventually come to an end. Therefore we need to
keep track of time. It is impossible to go back in time because
time is only a mental concept. For time travel to be possible there
would have to be an infinite number of realities all playing each
moment simultaneously. Even so we would have no way of accessing
these alternate realities. (Aside: Einstein says something
about reality that is applicable to time as well. He stated
"Reality is an illusion, albeit a persistent one.
...")
Time exists because without time, the six string theory comes
crashing down to a halt if you look at it carefully. It is not just
a mental concept because we die, it is as real as anything else,
and just because some people can't look behind the wall doesn't
make it any less real. If you could time travel, the most
complicated way is to send everything in reverse. But, I would most
likely use the void (using the theories of alternate realities,
there must be a void. otherwise the similar energy would merge (the
void is the space between universes of universal radiation, and
like two magnets repelling each other, the void is made up of a
repelling force), for it does not accommodate time in any sort; it
just merely exists, and you could basically just go from one spot
of the time-space in the universe to another.
But to answer the original question, no one can because you are
just being crushed into a size which most people believe to be
impossible to measure, so they call it infinitely small.
Research on all the science fiction standbys (time travel,
teleportation, etc.) is regularly reported in "Nature" magazine, a
stodgy, peer-reviewed, British science publication.
I have also found material prepared by Dr. Michio Kaku,
co-founder of the string field theory who has written on the role
of time travel in modern physics. In one of his discussions he
states:
"However, before Einstein died, he was faced with an
embarrassing problem. Einstein's neighbor at Princeton, Kurt Godel,
perhaps the greatest mathematical logician of the past 500 years,
found a new solution to Einstein's own equations which allowed for
time travel! The "river of time" now had whirlpools in which time
could wrap itself into a circle. Godel's solution was quite
ingenious: it postulated a universe filled with a rotating fluid.
Anyone walking along the direction of rotation would find
themselves back at the starting point, but backwards in time!"
"In his memoirs, Einstein wrote that he was disturbed that his
equations contained solutions that allowed for time travel. But he
finally concluded: the universe does not rotate, it expands (i.e.
as in the Big Bang theory) and hence Godel's solution could be
thrown out for "physical reasons." (Apparently, if the Big Bang was
rotating, then time travel would be possible throughout the
universe!)."
"Then, in 1963, Roy Kerr, a New Zealand mathematician, found a
solution of Einstein's equations for a rotating black hole, which
had bizarre properties. The black hole would not collapse to a
point (as previously thought) but into a spinning ring (of
neutrons). The ring would be circulating so rapidly that
centrifugal force would keep the ring from collapsing under
gravity. The ring, in turn, acts like the Looking Glass of Alice.
Anyone walking through the ring would not die, but could pass
through the ring into an alternate universe. Since then, hundreds
of other "wormhole" solutions have been found to Einstein's
equations. These wormholes connect not only two regions of space
(hence the name) but also two regions of time as well. In
principle, they can be used as time 苹果彩票."
Time is both a concept and physical, it is a concept because it
exists without being touched by anything, it is physical because we
exist in it.
Though there are mathematical ways that may allow one to
travel back in time, there is no real way to do that with
any technology that we know of. Time is real. It is real
just as space is real. We exist in the space-time continuum.
In a relativistic universe, time is part of space-time. What
is being debated is the nature of consciousness. And that is
addressed elsewhere on the boards.
Certainly time travel does happen in a black hole, if we
chose to look at it that way. It's possible in that time for the
(unlucky or lucky?) traveler who sails in will slow down. It won't
appear that way to that traveler, of course, but to the outside
observer, things will be slowing up until those outside observers
lose sight of the voyager making the trip into the unknown. Whether
or not the person travels back in time, goes "through" the black
hole and emerges somewhere and sometime else, or simply becomes
part of the collection of matter at the bottom of the gravity well
can be debated ad infinitum.
See the related question below. It is, "What is time?" It may
help, or it may not.
Time is REAL, although it is an illusion, because of Einstein's
General Theory of Relativity in where gravity can effect time. So
you see, because of the Earth and it's mass, and the other large
bodies of mass around us, it shapes our "time." If we were to go to
a different planet, it would have a different "time" than our own.
Where I am going with this, is that black holes have such immense
gravity, that it would completely warp time around you, but they
think that you can time travel in one.
It would have to be a rotating black hole so that the
singularity would be ring shaped, because then it could be skipped,
and thus (as is postulated) there would be an "Einstein-Rosen
Bridge" that would put you into another time/universe. But, the
bridge would always collapse right before entry, so you would be
crushed into oblivion in the singularity.
Asked in Physics, Time Travel
Is time travel possible?

Various opinions, then the problems... There are several
applications of theoretical physics that allow travel from one
point in space-time to another. Some address the issue of travel
into the past or the "future" but the concept of time as a "one-way
arrow" makes future travel simply suspended time followed by a
return to the present as the past.
Some calculations include theoretical rotating black holes and
their effects on time dilation (a generally accepted concept
related to speed in a separate reference frame). But the principle
of causation would create problems with interacting with or
altering the past, which created the world from which the time
traveler departs.
At the current time (no pun intended) we can't prove the idea of
time travel, seeing how we can not time travel right now. But we
also can't just discard the idea seeing how physics doesn't
disprove it.
Memory may be considered time travel, a one way image of the
past. If you can revisit the past through memory, that really is a
''time machine".
It is theoretically possible to travel back in time. When an
object is going extremely fast, such as the space shuttles, Time
slows down just a little. The astronauts come back 2-3 seconds
younger than they should be. This is called time dilation.
Now if we talk about, hypothetically, if an object with mass
traveling the speed of light, theoretically time would seem to
"halt". And if you go faster than the speed of light, time would
begin to go again, except backwards. In some mathematical theories,
this is possible. But the only problem with proving this theory
right is the Mass Factor. As you get closer to light speed, your
mass increases. When you are traveling at light speed, you have
infinite mass, which would make it impossible to go faster. Keep in
mind, this only works to travel back in time, theoretically.
One Way to the Future (time dilation)
If you were to travel into outer space and then return to Earth
at light speeds, you could actually "travel" thousands of years
into the Earth's future! This is because traveling at close to the
speed of light actually alters the passage of time: an object
traveling at extremely high speeds will not age in the same way as
an object which is static. So, if you were to stay on Earth, and
your friend was to travel into space and travel distances at the
speed of light and then return to Earth, your friend would return
to Earth much younger than you, even though you were the same age
before they left!
Einstein explained motion in time with his theory of relativity:
the stars bend time in space: it is time in space which dictates
how the planets move, and at what regularity. Time in space is not
absolute, i.e. it is not fixed, because it is relative to the speed
at which you are moving. So really, time travel already occurs!
But there are MAJOR Problems here...
It seems that all the answers here are talking about the
physical and fantastical possibility of time travel rather than a
common sense approach to its possibility, with a pragmatic
understanding of the limitations of physics and quantum mechanics.
There are several problems with the arguments.
To move backwards in time one would have to travel faster
than light, in the same way as hypothetical particles called
"tachyons", which would, if observed, disappear before they
appeared (if you could believe that). However, Einstein showed that
for a mass to travel at the speed of light it would require
an infinite amount of energy as the mass of the object
increases to infinity as well as time slowing down, so that an
infinite amount of force would be needed to accelerate that
infinite mass, and an infinite amount of energy needed to do so.
Therefore matter cannot travel at light speed, let alone faster
than light. Therefore, by Einstein's reckoning alone, time travel
would not be possible.
Secondly, as regards the principle of cause-and-effect, time
travel would cause great paradoxical problems.
The old chestnut of the grandfather paradox is a prime example.
Suppose you travelled back in time, and met your grandfather and
shot him dead, which may be perfectly possible. Your grandfather,
being dead, would not have sired your father and therefore you
would not exist - yet you must have existed to go back in time in
the first place. Such a paradox sounds silly, but is perfectly
possible if time travel existed. Therefore, anyone going backwards
(or forwards) in time cannot have any effect on the
surroundings (both in time and space)of where he or she ends
up.
Yet, the mere fact that they are there alters history. By
the Chaos Theory, even a minor event can create a major difference
in the nature of a place. Therefore just by being 'in history'
could eventually change that history so much that our "history"
would become different. But as it isn't different as texts,
documentation and sources tell us, not even minor events could have
been changed. In other words, no one must have been able to reach
the past to cause that change.
Thirdly, time travel is impractical even if you don't consider
the almost infinite energy required. It's because you also need to
consider the acceleration necessary to reach that speed. To
reach the speed of light (or near it) with an acceleration of 1g
(which would feel to the astronauts that they were back on the
earth although 'weightless' in space) would take over 54 years of
CONSTANT acceleration. Even at a constant 5g - the maximum
experienced by astronauts in the space shuttle, and then only for
very short periods because of the dangers, the time taken would be
13 years of constant 5g acceleration (meaning a 150 pound man would
weigh 750 pounds for 13 years - enough to break his bones unless it
was for a very brief period, let alone 13 years!). Even at 12g -
the point at which the human body experiences brown outs, loss of
peripheral vision blackouts, brain damage and death, even after
short exposure, the time needed would be over four and a half years
constant acceleration at this rate. Therefore, any attempt to even
get close to time dilation speed is absolutely futile.
Finally, if time travel will one day exist in the future, how is
it that we have never seen travellers from the future visit us? UFO
sightings are sometimes claimed to be 'time travellers' from the
future, but the evidence is very scarce for this - and even more
scarce for UFOs in the first place. It seems then that using simple
common sense, time travel is an impossibility.
So, I am sorry to disappoint everyone, but possibly Time Travel
should be confined to H.G. Wells and Dr. Who, for science fiction
is where it belongs. Einstein Would Say Yes
First of all, to travel through time (forward) is what humans
always do.
However, to travel back in time.... well, Einstein would say
it's possible. But the necessary technology currently does not
exist.
Time-travel as we consider it, will never be possible. Time is a
concept, but not a physical dimension or place, nor is it something
we can physically touch or measure. Time in reality is only motion.
The motion is only forward. No matter what we do, we are unable to
make this motion reverse and go backwards. At our best, if we
managed to go faster than light, we could only observe the effects
of what has happened, not reverse any of the processes of the
universe itself.
Einstein proved that time is relative. The faster the relative
motion of a traveling object, the slower the progression of time
observed in its reference frame. In effect, the aging of traveling
cosmonauts will slow down. Because motion is relative, a cosmonaut
who returns after traveling for 10 years at near the speed of light
may find that the Earth has aged 100 years or more.
This is not time travel. It is just a consequence of relative
motion on a subatomic level near the speed of light. The cosmonauts
may experience the effect as that they have traveled into the
future. But in reality, they have only slowed down their atoms'
motion, hence gaining the effect of slower/relative aging.
Wormholes may still exist (or be created) for traveling to
different places in the cosmos in a manner faster than light, but
in no way will this allow for actual time-travel. Not forward in
time - the perceived travel forward in time is a consequence of
relative motion due to high speed. Not backwards in time - we
cannot make universe go backwards.
The motion in the cosmos cannot be undone, hence we can not
travel back, only calculate motion backwards at best. By
calculations, we can simulate how objects move and behave backwards
and forwards in our concept of time. But to actually shift the
universe so that we can end up at a fixed "stored" physical image
of the cosmos itself...forget it.
Asked in Computers, Inventions, Benjamin Franklin, Time Travel
What are the dangers of having a time machine?

you could change time so something doesnt exist such as a
computer this would change everything as it is used in alomost
every job.also you could change time so a certain someone doesnt
exist such as the priminister then a war wouldn't happen then
slodiers would be doing different jobs people would still be alive
.The main risks are;
-changing something so someone or something doesnt exist
-getting stuck in the past/future coz something crushed your
time machine then you cant go back to the present day.
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