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Joined: 11/20/2008
Msg: 47
Time Travel to the Past is ImpossiblePage 3 of 4    (1, 2, 3, 4)

This also ignores the very "real" possibility that the mass transfer between times necessitates an energy transfer in a reverse direction, thus also satisfying conservation of mass and energy

That is how Isaac Asimov solved the problem in one of his science fiction stories. Even though it has been years since he wrote the stories, I like Isaac Asimov's science fiction the best because his stories did not violate the laws of physics. I have read several of his books.
Joined: 9/30/2008
Msg: 48
Time Travel to the Past is Impossible
Posted: 2/1/2009 10:09:29 AM

If it were possible you could go back and prevent one or the other of your parents from attending a party where only by chance your parents met while one was on vacation and returned home to another state the next morning. Therefore, they never met, you were never born so you couldn't go back in time to prevent their meeting.

That has always been my feelings Kelley and that reasoning blocks my brain from being able to conceive how time travel could be possible.
Joined: 3/24/2008
Msg: 49
view profile
Time Travel
Posted: 2/1/2009 11:02:15 AM

we can't travel in time and never will. If we could, someone would have come back and told us.
No, I wouldn't tell a soul. I'd just make a series of astonishingly lucrative investments.
Joined: 11/20/2008
Msg: 50
Time Travel to the Past is Impossible
Posted: 2/2/2009 1:33:17 AM
Itsallinthesoul to me it is similar to the mathematical proof by contradiction: The method of proof by contradiction is to assume that a statement is not true and then to show that that assumption leads to a contradiction. Since assuming that example of time travel leads to a contradiction then time travel is impossible.

Also, as someone pointed out, if time travel were possible, where are they? If it were possible than sometime in the future someone would invent a way and people from the future would travel to the past. Since they haven't, time travel to the past is impossible. However, I believe the proof by contradiction is better.
Joined: 1/12/2008
Msg: 51
Time Travel to the Past is Impossible
Posted: 2/2/2009 2:45:08 AM

Itsallinthesoul to me it is similar to the mathematical proof by contradiction: The method of proof by contradiction is to assume that a statement is not true and then to show that that assumption leads to a contradiction. Since assuming that example of time travel leads to a contradiction then time travel is impossible.

General relativity does not preclude time travel. The most famous example of a universe with timelike curves that close is the Godel Universe. It is believed that time travel is not possible in this universe (Hawking's chronology protection conjecture), but that has not been proved as a theorem.
Joined: 10/29/2006
Msg: 52
Time Travel to the Past is Impossible
Posted: 2/2/2009 3:35:13 AM
If time travel were possible I would definitely go back to earlier yesterday, and warn myself not to indulge in the Taco Bell offerings.
Ohhhh. Ta-co Bell, Taco Bell, goes straight through me...Ta-co Bell.
Joined: 5/12/2008
Msg: 53
Time Travel
Posted: 2/2/2009 8:23:44 PM
I am absolutely intrigued by the subject of 'time-travel', and especially how it relates to the quantum foam level in Quantum Physics where 'if' the perfect worm hole could be enlarged (and 'remain' enlarged, without collapsing) long enough to slip through? ...Thus time-travel?...Quantum foam is the micro-level of the universe where things are so very small that we are unable to observe them.

I do have a basic understanding of the Theory of Special Relativity, but I have a measure of confusion in reaching a true understanding as to the Twin Paradox! Putting the Doppler Effect aside, (because it is not what constitutes the dilation of 'time', I can understand the Twin Paradox, if it's taken/viewed at each instance/concept/fact separately, step by step. Then it makes sense to me, however, observing the entirety with full understanding is a totally perplexing for me. If you have an understanding of this moreso, then please enlighten.

Anyway...quantum also referred to as spacetime foam, and is a concept in quantum mechanics. The foam is supposedly the foundations of the fabric of the universe, but it can also be used as a qualitative description of subatomic spacetime turbulence at extremely small distances of the order of the Planck length. (The Planck length is the unit of length approximately 1.6 × 10-35 metres...From thus arose said Planck Time). At such small scales of time and space is the "uncertainty principle".

In quantum physics, the Heisenberg Uncertainty Principle or the Heisenberg Indeterminacy Principle allows particles and energy to briefly come into existence, and then completely obliterate without violating conservation laws. As the scale of time and space being discussed shrinks, the energy of the virtual particles increases. Since energy curves according to Einstein's theory of general relativity...this suggests that at sufficiently small scales, the energy of the fluctuations would be large enough to cause significant departures from the smooth spacetime seen at larger scales, giving spacetime a "foamy" character. However, without a "theory of quantum gravity", it is impossible to be certain what spacetime would look like at these scales, since it's thought that existing theories would no longer give accurate predictions in this domain.

Quantum foam is theorized to be created by virtual particles of very high energy. Virtual particles appear in quantum field theory, where they arise briefly and then annihilate during particle interactions, in such a way that they affect the measured outputs of the interaction ...even though the virtual particles are themselves never directly observed. They can also appear and annihilate briefly in empty space, and these "vacuum fluctuations" affect the properties of the vacuum, giving it a nonzero energy known as vacuum energy, a type of zero-point energy (however, physicists are uncertain about the magnitude of this energy ).

The Casimer Effect can also be understood in terms of the behavior of virtual particles in the empty space between two parallel plates. Ordinarily quantum field theory does not deal with virtual particles of sufficient energy to curve spacetime significantly, so quantum foam is a speculative extension of these concepts which imagines the consequences of such high-energy virtual particles at very short distances and times.

The "foamy" spacetime would look like a complex turbulent storm-tossed sea. Some physicists theorize the formation of wormholes therein. Speculation arising from this includes the possibility of hyperspatial links to other universes (Which I totally believe exists.) A multiverse is the hypothetical set of multiple possible universes that together comprise all of physical reality. (A great topic for another time. It's freaky what they are doing in labs these days to "create" universes! Really hard to wrap my mind around!)

So many if-if-if's...
Joined: 3/30/2008
Msg: 54
Time Travel
Posted: 2/2/2009 9:33:17 PM
I think time travel is possible , we just dont know how yet . Just because we dont know or understand something ,doesnt mean it isnt possible.
I know nothing of science and dont have anything to back up my thoughts , they are just that thoughts.

I am thinking that time travel does not have anything to do with moving at the speed of light , wormholes , blackholes or anything like that...its done through the mind without leaving your chair. I say that because our bodies are mere recepticals to hold our spirit or soul.When looking at the big picture ,we are in these shells and on this earth for less then a blink..then we disgard them back to the earth..if we have a soul or spirit is this not the time that it moves on ? no longer requires a body.
So looking for time travel in a physical sence to me isnt the answer , I could however see it happening in a spiritual way. Perhaps like an out of body experience ,only much more in depth. I think the ability to time travel is starring at us in the face . I think its a part of us that we have yet to discover , but are are the edge and within reach .
I think I read somewhere that humans use around %70 of thier brain....yes...some even
It might be amazing at what we could see and do if we could tap into the rest of it.

My PERSONAL thoughts are its all tied into the Pineal gland . I think if we are ever going to travel time and perhaps find other forms of life it will be done on more of a spiritual level and without a "body" . To me dreams are a form of time travel , they take us places , show us experiences and deliver us safely back to bed as" if" nothing has happened..but it did.
Dreams are scrapeing the surface of other worlds , were still babies in this world and dont now how to control it yet is all...BUT...when we do find out about mind control..... (in the good sence)... the floodgates of wisdom will spill on our feet.

I know its a far out thought ..but its I squint real hard I can almost see palm trees dammit

Joined: 4/24/2007
Msg: 55
Time Travel
Posted: 2/3/2009 9:25:16 PM
couple things...and bare with me...i have no education so my structure/gramar sux:)

i only have plenty of time on my hands and read alot and watch alot of documentaries...

first off time travel with our dimensions is not possible (beeing able to travel thru time would involve another dimension that we cannot feel so in essence...well)

so now if you suggest time travel is done by going speed of light...again thats not travel....much like the mirror your merely feeling as tho you cheated time that one second only cause you went so could go 100x the speed of light and travel 100 million lights years in 5 still took 5 seconds....time is constant in our dimensions

if you wish to talk blackhole theories n such and how matter disapears ...well from what i read we dont know enough about this and i *think* this is where we get into another dimension we cant understand and truely imho blackholes even if it creates another dimension is by pressures/forces that humans could never truely exsist in so that path is closed...for now:)

another point i noticed and i have such a hard time watching is how anyone can put a size to the universe....what is the definition of universe to you folks who put a distance to it??

The universe is defined as everything that physically exists: the entirety of space and time, all forms of matter, energy and momentum, and the physical laws and constants that govern them. However, the term universe may be used in slightly different contextual senses, denoting such concepts as the cosmos, the world or Nature.

Current interpretations of astronomical observations indicate that the age of the universe is (13.73 ± 0.12) billion years,[1] and that its diameter is at least 93 billion light years, or 880 ×1024 metres (that is to say, "880 followed by twenty-four zeroes" metres).

According to the prevailing scientific theory, the universe has expanded from a gravitational singularity known as the Big Bang, a point in space and time at which all the matter and energy of the observable universe were concentrated. Since the Big Bang, the universe has been expanding to its present form, possibly with a "brief period" of cosmic inflation.[2] Several independent experimental measurements support this theoretical expansion and, more generally, the Big Bang theory. Recent observations indicate that this expansion is accelerating because of the low density of the universe, and that most of the matter and energy in the universe is fundamentally different from that observed on Earth and not directly observable (cf. dark matter and dark energy). The imprecision of current observations has hindered predictions of the ultimate fate of the universe.

Experiments and observations suggest that the universe has been governed by the same physical laws and constants throughout its extent and history. The dominant force at cosmological distances is gravity, and general relativity is currently the most accurate theory of gravitation. The remaining three fundamental forces and all the known particles on which they act are described by the Standard Model. The universe has at least three dimensions of space and one of time, although extremely small additional dimensions cannot be ruled out experimentally. Spacetime appears to be smooth and simply connected, and space has very small mean curvature, so that Euclidean geometry is accurate on the average throughout the universe.

couple of things....saying the universe never ends but that it comes back to you in a large circle (because you send light one direction then it arcs til it hits ya in the back of the head) are people retarded??? i mean that only would prove (if we could prove light arc'd) that within the universe this is what light particles do....and some folks then measure this with time which leads them to believe time bends as

grow the hell up...this sorta crap is werse then religeon and look how much help this did to humanity....i cant be the only person that realizes til we run into a wall while were in our little Enterprise we need to maintain the universe is infinite....same as datign the universe.....this is crap....fine if you want to toss a date on the big bang theory thats alright....but before this bang and the billions of bangs/collapses (if this theory is correct) there was still time....if not what was before this??? that is when you let the evilness in....people will start to think "a god created the universe"

stick to what you know .....the universe has infinite time and distance til we hit a wall or stand still......and even then whats on the other side of that wall?? :) and for us to stand still (time wise) we would have to *feel* time or measure it...and how can ya measure it if we are standint still....

so in essence we cant change that time and space is infinite .....and i can say with the dimensions we currently have at our disposal this is 100% constant:)

now its okies for you smart mofos to go out there and try and bend time and distance but dont confuse the simple folks with your theories and suggest putting a limit on gods and allow yourself to think larger then what you think you can comprehend:)

for instance light particals bending in an arc and hitting you in the back of the head....nonsense....gravity would obviosuly effect this and no way it would hit ya in the back of the head in a single arc....because the universe is not FLAT(my attempt at humor world flat thingy)...lawl christ look out your window if ya dont believe me....alot of stars up there all mixed up and no straight why suggest that the light would bend at the same rate would bend up down left and right all over....and yes because time is infinite it would hit ya in the back of the head but that isnt an arc..... over time it would hit you and your mother in law in the back of the head:) oh right this is a singles dating site so your ex mother in law:)

another point big needs to be explained better that yeah the big gang theory is most likely what happened (collapse expand idea more like) but its only what distance we can comprehend other worlds the universe we can see sure....but even that i think the universe is alot more complicated then this and i woud think what we see as the begining of our big bang (13.73 ± 0.12) billion years ago wasnt a single bang but mutliple understadn this now you gotta understand size.....when it all imploded was the distance between the atoms 1 billionth of a centimeter or was it 10 billion miles....and how many clusters....was it all at the same time or over 1 billionth of a second or over 10 million years??? you cannot say it was all at once and all in the same space because then again your limiting your ability to comprehend ....

i agree that big bangs happen (thru gravity) what i think is stupid is anyone who thinks there was a definitive time and size to can give an opinion that it was a certain size and your reasons why ....but dont try and bs folks by suggesting it was all in one moment and all in one place.....

and why i feel so strongly about this?? because i see other publications that use big bang theories as there base ....and that is wrong.....ya need to figure out thebase first before you continue or your only adding fiction ontop of fiction....and that is tragic ..

anyhoo peace

Joined: 4/24/2007
Msg: 56
Time Travel
Posted: 2/3/2009 9:33:18 PM
oh i might want to add...

my theory with black simply light beeing trapped in dense matter.....til we are able to actually observe one close up we canot tell if that dense matter is expanding or beleif is that yet again there is no wizard on the other side of the curtain (curtain beeing the light patterns) but that the dense matter is simply getting more dense or larger ....most likely at a rate faster/slower (or type of matter within) not allowing it to explode like most stars do....

purty simple theory and maybe others believe this i simply havent come accross it yet:) if anyone knwos a theory close to this i woudl love to read up on it:)
 captain wolfe
Joined: 1/30/2009
Msg: 57
Time Travel
Posted: 2/4/2009 8:02:36 PM
i 100 percent believe in time travel i think the army has been makeing machines on it but you can not send a person back or forward only letter or small notes only time will tell,
Joined: 3/30/2008
Msg: 58
Time Travel
Posted: 2/5/2009 3:19:26 PM

i think the army has been makeing machines on it but you can not send a person back or forward

If a person was to get inside one of those time machines and set the dial for 50 years either way, what would happen to the physical body ?.Wouldnt it age as well , perhaps arrive at the destination with a skeleton at the wheel....thats another reason why I see time travel as a "spiritual" thing.
What would a person do to feed the physical body ,in a land where food as we know it doesnt excist . If there is other life out there I doubt they are eating peas and carrots tonight, and then going out after supper to look at earth through a telescope.
Yet I can close my eyes and travel to anytime frame I can imagine , I can jump from the moon over to saturn if I limitations for the mind but the body has to many limitations to time my humble opion that is.
Joined: 6/23/2006
Msg: 59
Time Travel
Posted: 2/5/2009 4:40:48 PM
If you can travel back in time before you were born then you didn't need to be born to exist (because you haven't been born yet, but still exist). So no problem killing him.

Absolutely correct. It kinda makes movies like Back to the Future and Timecop seem silly, but it makes logical sense. The reasoning behind it is that as soon as you go back in time and change something (killing your mother before she met your father for example), you instantly becme part of an "alternate" reality; one in which YOU were never conceived. Your actions in this other reality won't influence the outcome of what happens in YOUR origin reality. Therefore, your existence is permanently independent of your activity in the new one. It doesn't make for good Hollywood movies, but it's more likely to be accurate.

The temporal causality loop was often used to explain why it's really impossible to change the past too (going back in time to kill your mother before you were born actually fails and CAUSES her to meet your father nd conceive you), but this explanation, although entertaining, is probably not the best explanation for what would really happen if one were to travel back in time.
Joined: 11/20/2008
Msg: 60
Time Travel
Posted: 2/10/2009 2:28:01 PM

Well,,,,time ,,,,,,in its simplest form,,,is the elapse of light,,,,having said that,,,take for instance,,,,,,were a person to board a spacecraft on one planet,,,,travel a considerable distance from THAT planet at the speed of light X's Pi,,,,,land on another planet,,,,look thru a telescope mathematically pointed in the direction of the planet he came from,,,would he not see himself boarding that spacecraft,,,example,,,the light we are seeing from all the stars in the sky took how long to get to earth?

You can see the past, but you cannot travel to the past. Time travel to the future would be possible if you could be frozen and revived 10,000 years later.
Joined: 1/12/2008
Msg: 61
Time Travel
Posted: 2/12/2009 4:01:53 AM

You can see the past, but you cannot travel to the past.

Well, everything you see is in your past, but whether or not one can travel to the past is an open question, although, the answer is that you probably can't. However, if you recall the pythagorean theorem, the general name for it is a ``metric'' and in a 4-d spacetime with 1 time dimension, it has the form,

ds^2 = -adt^2 + b(dx^2 + dy^2 + dz^2)

The coefficients a,b are determined by solving the field equations for a particular matter and energy distribution. Intervals in which ds^2 are negative are called timelike. Intervals in which ds^2 are positive are called spacelike. (However, in particle physics, the convention is to reverse the signs in the metric, in which case the definitions reverse.) Your future and your past are always along a line which is timelike, since you started in your past and will continue toward your future. If you can find coefficients a,b (which are actually functions that can include the coordinates as arguments, not simple constants), which start and end at the same point in spacetime but for which ds^2 is negative, you have a closed timelike curve. i.e., you've traveled into your own past. (an example of a closed spacelike paths is a circle.) It is believed that this is probably not possible, but it's an outstanding question, since such regions are predicted to occur in, for example, Reissner-Nordstrom black holes at the inner horizon (known as a Cauchy horizon.) The Godel universe is an exact solution of the field equations which yields closed timelike curves:

ds^2 = { -(dt+ exp(x)dz)^2 + (1/2)exp(2x) dz^2 + dx^2 + dy^2 }/2w

where w is the angular velocity at which the universe rotates.
Joined: 12/31/2008
Msg: 64
Time Travel
Posted: 3/13/2009 3:38:19 AM
My kind of thread!
As a child I read soooo much history and wondered "what if the slightest action were altered?" It would change everything.
A very good fictional read is Jack Finney's "Time and Again".
Joined: 6/26/2008
Msg: 65
Time Travel
Posted: 3/13/2009 2:21:32 PM
I time travel all the time, every moment that passes is traveling in time. And many people live in the past instead of the present. Ok, ok, I know that is lame.

Aren't there theories that time doesn't necessarily go in a "straight line". That it may loop around and around and there are points that overlap. Another conjecture is that there are parallel lines of time. And other such ideas.


Maybe I read too much sci-fi.

I have no idea about whether time travel is or is not possible. I know it's interesting to think about the possibilities.
 Sun Shine222
Joined: 10/31/2009
Msg: 66
Time Travel
Posted: 11/22/2009 2:46:57 PM
Research Ive done on this subject points to some of the UFO phenomenon as being inter dimensional beings from our future traveling through time. Ive attached a interesting link.
Joined: 1/16/2008
Msg: 67
Time Travel
Posted: 3/29/2010 8:16:35 AM

Research Ive done on this subject points to some of the UFO phenomenon as being inter dimensional beings from our future traveling through time. Ive attached a interesting link.

I read that novel too. It was a great work...of science fiction!
Joined: 1/12/2008
Msg: 68
Time Travel
Posted: 3/29/2010 8:39:59 AM
The general theory of relativity (which is a theory of spacetime geometry) doesn't exclude time travel. For example, the Godel universe is an exact solution to the field equations which results in closed timelike curves. On the other hand, our universe doesn't appear to allow the conditions which permit time travel in the Godel universe. So, the anser is that most physicists suspect that time travel is not possible and would like to show conclusively that it is or isn't possible, but so far, the impossibility is only conjectured.
Joined: 12/1/2014
Msg: 69
Time Travel
Posted: 12/14/2014 10:37:10 AM
Twill348 has a nice way of putting it.

Time travel is a lazy writers crutch. It is not possible. You don't need a lot of reasoning to see why.

You can't "go" to some place that does not exist.

It is true, that time is a concept, and a concept only, that people invented to make sense out of repeating events. But people are hardwired to treat words and ideas like baseballs, as though they are real things you can toss around. So "time" becomes real, to those who can't think very well. Unfortunetly, this includes most scientists, and science writers.

There is only the present. That's all there is. No past, no future, only existence. There is nowhere for a time machine to "go" to. You get in, the lights flash, you get out...still there, in the present. You don't go anywhere.

This is the only reality: something is, something happens, there is change. But change is not traveling thru time, it's just change.

Of course, objects experience change at different rates, depending on a number of factors. But show me one object that has ever left the present.

As I underswtand it, Einstein never considered spacetime to be a reality, just a mathematical analogy.
Joined: 10/27/2014
Msg: 70
Time Travel
Posted: 1/25/2015 5:53:14 PM

if you could go as fast or faster than light you could stand in front of someone and go around the world and come back before the light reached the other persons eyes it would look as though you never moved but infact you did move.

No, that's not correct if you're going as fast as light. You would need to go faster. Light going 5 feet takes a shorter amount of time than light (or you going as fast as light) going around the earth and back.

If you are as fast or faster than light you can do anything you wish before light catches up with you. Freezing time in a sense

Going as fast as light, yes, time "freezes". Or in other words, it's INSTANT to you. Time does not pass. The closer you go to the speed of light, the slower time 'ticks' for you. In a general nutshell, the speed of light minus your speed is going to determine how fast time ticks by for you. It's not on an even scale, though. You need to be Close to light speed for it to make a big difference.

The universe is estimated to be about 157 billion light years large. So if you rode a beam of light from one end of the universe to the other it would take 157 billion years to get there.

No -- it would be INSTANT for you. To those living on the other side of the universe, it would take 157 billion light years for you to arrive. To you? Instant. Time does not 'tick' at the speed of light. There is no time.

However, if you decided to not ride a beam of light and somehow managed to get to the other end of the universe in less than 157 billion years then you will have effectively travelled faster than light.

YOU would get there in less than 157 billion years, subjectively. Objectively, yes, it took 157 billion years to get there, in reference to those outside the box. That's why time's relative. So YOU could get there in, say, 15 billion years without even breaking the speed of light (but coming darn close to it).

Of course, the universe is expanding -- so it'd take longer than that. :)

The same is true for the universe except that quilt is unimaginably big and the planets and stars are the ones causing the curviture of space.

... at certain points where they are, yes.

I'm more interested in the concept and the possibility which sounds really cool. Thoughts?

Going faster than the speed of light, yes, would theoretically bring you BACK in time. Matter cannot go faster, just as matter cannot go as fast. Matter increases it's mass, the faster it goes -- just as it decreases the amount of time that's elapsing, relative to the outside world at rest. If you're on the cusp of going the speed of light, you're on the cusp of having infinite mass. Not blackhole-sized. WAY WAY WAY WAY bigger. Matter can't go the speed of light; it can't go faster, either.

I think what would be investigated is sending non-matter faster than the speed of light -- so therefore sending information faster, thus, in the past? ("Hey, wear a condom, d!psh!t!")
Time Travel
Posted: 1/27/2015 3:29:36 PM
The last two posts (one really being twill348) strike me as a good way of communicating the subject. I learned a bit just from reading the way twill was expressed. Felt like a derp.
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