Is time travel to the past impossible?

[cousinbasil]

Energy burning goes forward in time.
Energy retracting to where it came goes back words in time.

I know it is not impossible. Nothing that the brain can conceive is impossible.

How about a square circle? According to you, it is impossible to conceive of something that is impossible. That can't possibly be true.

[Glostik91]

Time travel to the past is possible! (under certain conditions)

Here are some possibilities:

1. Lucid dreaming
2. Fly out into space faster than the speed of light. Turn around toward earth and point a massive telescope at it. You will see the past as its unfolding. Refract the light going into the telescope into a machine similar to an imax dome that can produce 3d holograms.
3. Transport yourself into another universe that is exactly like ours except time is in whatever time you want it to be. Things can change in this universe because it isn't the universe you're from.
4. Build a virtual world on a supercomputer of whatever time you want and then plug yourself in like the matrix.

These were just off the top of my head.

[alphaeg]

Energy burning goes forward in time.
Energy retracting to where it came goes back words in time.

I know it is not impossible. Nothing that the brain can conceive is impossible.

How about a square circle? According to you, it is impossible to conceive of something that is impossible. That can't possibly be true.

I just envisioned a square circle in my mind, my thoughts being real things, just brought the square circle into existence.

[cousinbasil]

I just envisioned a square circle in my mind, my thoughts being real things, just brought the square circle into existence.

What does it look like? What are its properties? You are missing the point. You have something in your mind that you are calling a square circle. A square has certain properties. So does a circle. They are mathematical constructions with numerous logical implications that are all self consistent. You cannot have a square circle by what the words square and circle connote, which are these very implications or properties.

[alphaeg]

I just envisioned a square circle in my mind, my thoughts being real things, just brought the square circle into existence.

What does it look like? What are its properties? You are missing the point. You have something in your mind that you are calling a square circle. A square has certain properties. So does a circle. They are mathematical constructions with numerous logical implications that are all self consistent. You cannot have a square circle by what the words square and circle connote, which are these very implications or properties.

It is a circle with the tips of the squares poking out in the corners.
It is a circle with a square inside the circle.
It is a square with a circle inside the square.

It is anything I want and makes perfect logical sense.

[cousinbasil]

It is a circle with the tips of the squares poking out in the corners.
It is a circle with a square inside the circle.
It is a square with a circle inside the square.

It is anything I want and makes perfect logical sense.

So it is not a circle and it is not a square. If it is not a circle, then it cannot be any kind of circle, including a square one. And since a circle is a circle with properties that do not change (aside from size) and the same can be said for a square, what you have described is not any one thing so cannot be the same class of "real" as they are. If it can be anything you want, it is not real in the same sense as a circle, which can not be anything you want.

[alphaeg]

It is a circle with the tips of the squares poking out in the corners.
It is a circle with a square inside the circle.
It is a square with a circle inside the square.

It is anything I want and makes perfect logical sense.

So it is not a circle and it is not a square. If it is not a circle, then it cannot be any kind of circle, including a square one. And since a circle is a circle with properties that do not change (aside from size) and the same can be said for a square, what you have described is not any one thing so cannot be the same class of "real" as they are. If it can be anything you want, it is not real in the same sense as a circle, which can not be anything you want.

No matter what I say, it would not be sufficient for you.

You have already made up your mind that a sqaure circle cannot exist.

Your whole sqaure circle thought is flawed anyways because you use it in a context saying:

A dog/computer could not exist. But if I made a robotic dog you would then say it is not a computer nor a dog; because a computer and a dog have properties that do not change.


To a sense, logically you are correct.
But to a bigger sense; logically it is impossible for a computer/dog to exist in reality; so you must settle for the robotic dog which is possible in reality. Your original thought will always change as it adapts to the limitations of reality.

So yes a sqaure circle cannot exist OBVIOUSLY.

But with imagination we can create a sqaure circle that CAN exist in reality.

If you wish to personally limit yourself by thinking something is impossible go right ahead.

I am more fulfilled and capable knowing that impossible is trying to say I'm-Possible.

[cousinbasil]

No matter what I say, it would not be sufficient for you.
You have already made up your mind that a sqaure circle cannot exist.

I think I am just restating A=A. I have no particular quarrel with or interest in a square circle – or what you are calling one. Your original claim was that if it can be imagined, it can exist. That may be true. It may be true that what can be imagined already exists, it is merely waiting to be discovered. But in order to navigate in the endless sea of dualism, I think one has to agree on terms. If your belief is literally that nothing is impossible, what does the word “impossible” mean, if nothing has that quality?

Let me give you another example if the square circle thing is not getting across to you. Suppose I imagine two sets, A and B. If something belongs to set A, it cannot belong to set B. If something belongs to set B, it cannot belong to set A. The sets A and B are mutually exclusive.

Now I ask the question, is it possible for a thing to belong to both sets A and B?

It's not a trick question. I think people just naturally classify some things as "impossible." I definitely do not get why this would be personally limiting. If I believed every thought that came into my head was on the same footing as far as possibility goes, I'd probably go grab the nearest third rail.

I am more fulfilled and capable knowing that impossible is trying to say I'm-Possible.

Sounds like a Tony Robbins mantra.

[alphaeg]

I am more fulfilled and capable knowing that impossible is trying to say I'm-Possible.

Sounds like a Tony Robbins mantra.[/quote]

lol

What I meant to say in my last reply was;

Being too logical can be the opposite of genius in certain situations or debates. In my opinion, this is one of those occasions.

[cousinbasil]

I am more fulfilled and capable knowing that impossible is trying to say I'm-Possible.

Sounds like a Tony Robbins mantra.
lol

What I meant to say in my last reply was;

Being too logical can be the opposite of genius in certain situations or debates. In my opinion, this is one of those occasions.

Well, you're right there. But then, one is either a genius or one is not, and I know I am among the latter group.

edited - cousingenius had one too many code items in the original.

[alphaeg]

I would have to disagree.

Going by how this forum defines 'genius'; I would say being genius is software more than hardware.

You don't necessarily have to be born a genius to become a genius. If you were to change your outlook on life; I'd say anybody could transform them self into a genius. It's a train of thought more than anything else.

Being extremely logical (in my opinion) can be very counter productive. You don't have to actually be smart to think smart.

[cousinbasil]

You don't have to actually be smart to think smart.

Maybe not. But then what does it mean to be smart? When you say someone is smart, aren't you describing how that person seems to think? In other words, if one "thinks smart," assuming the thinking translates into action, of course, doesn't that mean one is smart...?

[Jeff Williams]

Atomic Research Centre Europe in recent years, researchers found that positive and negative K meson in the conversion process there is the asymmetry of time. this is the first time in the history of physics of time asymmetry observed directly, a more direct proof of the time could turn the clock back.
On the other hand, for some super-human anomalies "hunch" capacity (such as the famous Edgar Cayce predicted) of mystery, also must be based on "time back" theory to the scientific basis be reasonable on the interpretation . Secondly, in theory, "time back" also have certain conditions. To achieve "time back" in two ways: first, ultra-light, the second is the "wormhole" .

------------------------------------------------------------------------

[cousinbasil]

this is the first time in the history of physics of time asymmetry observed directly, a more direct proof of the time could turn the clock back.

It has long fascinated physicists that the laws of physics, when stated mathematically, are time invariant. You can replace "t" with "-t" and still have valid equations. That is, there seems to be no preferred direction of time. The classic description of it is if you filmed any physical process and played the film backward, while things might "look funny," no physical laws would be observed to be broken.

Your statement here indicates research with which I am not familiar - perhaps you could post a link or two to the experiments you are citing. Such experiments, I am guessing from your description, would violate physical laws if "played" in reverse. So I am not sure why they are any indication that "time back" as you put it - I assume you mean travel back in time - is more possible than previously thought. It would seem the opposite, if time really had an arrow.

From Wikipedia on Wormholes (my italics):

There is no observational evidence for wormholes, but on a theoretical level there are valid solutions to the equations of the theory of general relativity which contain wormholes.... Physicists have also not found any natural process which would be predicted to form a wormhole naturally in the context of general relativity, although the quantum foam hypothesis is sometimes used to suggest that tiny wormholes might appear and disappear spontaneously at the Planck scale...

I just wanted to put things in perspective. The existence of wormholes cannot prove "time back" is possible, since their existence has never been observed. They remain theoretical constructs, at least at present.

[eyekwah]

t has long fascinated physicists that the laws of physics, when stated mathematically, are time invariant. You can replace "t" with "-t" and still have valid equations. That is, there seems to be no preferred direction of time. The classic description of it is if you filmed any physical process and played the film backward, while things might "look funny," no physical laws would be observed to be broken.

The process of burning is not something which can "make sense" backwards as well as forwards. Tea cups don't leap off the floors and reassemble in your hand. Supernovas don't collapse in such a manner as to create an unstable yet stabilizing white dwarf star. Entropy always has a single direction, and Hawking claimed that was synonymous with the flow of time and the expansion of the universe in that they all must point in the same direction.

If that wasn't what you intended, I apologize that I misinterpreted.

Time may be an illusion, but only because we can't measure it as if it were another dimension. The effects of time flow change so very little at low speeds relative to c that it's really no wonder we've always thought of time like a measuring stick. It took 200 years before Einstein realized that the pull of gravity was not a parabola as originally thought by Newton but rather a really large elliptical orbit centered around the center of gravity. Maybe it'll take another 200 before we can begin to see time for what it really is.

[cousinbasil]

The process of burning is not something which can "make sense" backwards as well as forwards. Tea cups don't leap off the floors and reassemble in your hand. Supernovas don't collapse in such a manner as to create an unstable yet stabilizing white dwarf star. Entropy always has a single direction, and Hawking claimed that was synonymous with the flow of time and the expansion of the universe in that they all must point in the same direction.

If that wasn't what you intended, I apologize that I misinterpreted.

Not what I intended, but no need to apologize, because I understand your exception perfectly well. It took me a while to overcome the same objection and grasp the point as I stated it above.

Time indeed has an "Arrow" but it is not reflected in the laws of physics as such. Thermodynamics and the concept of entropy rely on the behavior of an unimaginably large number of particles. Each particle does not display the statistical effects of the aggregate. Physical laws which govern the motion of each particle are expressible by equations in which the time variable can be replaced by its mathematical inverse and the equations are not violated.

You mention tea cups not reassembling after shattering and then leaping back into place on a table. This is a matter of probability only. The same large numbers come into play when one considers gambling. It is just as likely to roll a six as any other number on a die. Yet roll that die a thousand times and you would not say it is impossible to get all sixes although you might then conclude the die is loaded. If you knew it was not, you still cannot say that a thousand sixes in a row can not occur on physical grounds, or be 100% certain it will not. It would not violate any physical law. This is the entirety of my point. Now make it a billion rolls - or roll a thousand dice a million times. All sixes for each is still physically possible. Yet would the reassembling tea cup be any more startling? If so, simply roll more dice! At some point, the two are equivalent in that they are as precisely as unlikely to occur (or precisely as likely, no?) At no point does the experiment with the dice violate the laws of physics - and so would the reassembling tea cup violate no physical law.

Remember - engineering certainties are physical probabilities.

[eyekwah]

I agree with you that even the most improbable circumstances are still possible. However, it's one thing discussing the probability of rolling 6 a thousand times, and quite another to think that shattered tea cups returning to one's hand and reversing the effect of burning an object, albeit improbable, could still happen.

Suppose for a second that you had an ice cube and you let it melt to water. It's tempting to think that you could take that water, being careful not to lose a single molecule of H20, and let it return to its previous state in the freezer. However, energy is lost in the process of putting the water back into the ice tray, placing the tray back into the freezer, and removing heat from the water in order to cause it to freeze. The molecular movement of the water molecules in the newly formed ice cube aside, much has changed in the universe since the first time it was an ice cube, some small part of which is directly due to energy lost attempting to put the ice cube back to its original state. Likewise you could never hope to repair a tea cup or "unburn" a piece of paper.

This is impossible unless the very flow of time itself were moving backwards in the same direction as entropy, which evidently is not the case. Anything improbable is possible, though that doesn't make the impossible possible by any means. There doesn't exist a universe for every possible universe you could imagine, only a universe for every *possible* universe.

[cousinbasil]

I agree with you that even the most improbable circumstances are still possible. However, it's one thing discussing the probability of rolling 6 a thousand times, and quite another to think that shattered tea cups returning to one's hand and reversing the effect of burning an object, albeit improbable, could still happen.

Not in principle, though.

Remember, the laws of physics are what is in question, not the behavior of the die or the teacup. My point was that neither the die or the teacup reassembling can be viewed as impossible just considering the physical laws we have at our disposal.

I suggest that the teacup scenario might even be more likely than the thousand sixes in a row. The probability of the latter is unimaginably small, even with a thousand throws - and my example used a million throws. It is (1/6)exp(1000).

Impossible things are things that logic does not permit - see David's many invocations of the "square circle."

While you may think it illogical to suppose the teacup could ever reassemble, the laws of physics would not be violated if it did.

I am not saying, in other words, that "impossible" is impossible.

[eyekwah]

Impossible things are things that logic does not permit - see David's many invocations of the "square circle."

Therein lies the heart of the issue. I don't think anything is possible with the only exception being the things which cannot possibly be possible by definition. Saying that a universe exists which is comprised entirely of banana peels is not impossible because it cannot be possible by definition. It's impossible because in such a universe there would have to be banana trees to have grown them and monkeys to have eaten and discarded them. Yet I say there are no monkeys or banana trees. Only empty banana peels. This is not venturing into the realm of the extremely improbable. This is impossible.

I'll be the first to admit there are a good many things which seem impossible but in fact are simply extremely improbable. However, you're willing to admit that any universe I could come up with without a self-contradicting definition in it somewhere lies in the realm of the possible.

In a way, probability is like a degree of freedom much like x, y, and z. Whereas rather than traverse space, you're traversing possibilities. However, like x, y, and z, you can't possibly expect to have visited every part of the known universe by treading the x axis and neither can you see any universe by treading the probability axis. The realm of what is possible is a huge realm, but it's infinitely small when compared to the realm of what is impossible.

[cousinbasil]

Saying that a universe exists which is comprised entirely of banana peels is not impossible because it cannot be possible by definition. It's impossible because in such a universe there would have to be banana trees to have grown them and monkeys to have eaten and discarded them. Yet I say there are no monkeys or banana trees. Only empty banana peels. This is not venturing into the realm of the extremely improbable. This is impossible.

I understand what you are saying. See my discussion with alphaeg earlier in this thread. His tenet was if you can imagine it, it is not impossible. Which would mean it is impossible to imagine something impossible - a logical contradiction, since you just have.

So I do agree about the banana peel universe scenario. That is impossible because it is a logical contradiction as you have described.

However, you're willing to admit that any universe I could come up with without a self-contradicting definition in it somewhere lies in the realm of the possible.

I wasn't aware I was admitting anything, since this was my original contention.

In a way, probability is like a degree of freedom much like x, y, and z. Whereas rather than traverse space, you're traversing possibilities.

You're very close to the commonly-accepted modern view of physics. Probability is estimated using phase space instead pf merely space. Phase space is invariably of higher dimension than the physical space it describes. A common formulation is to take each particle of a system and assign it three numbers corresponding to its location, and three more to describe its momentum vector. There fore the dimension of such a system in phase space is 6N, where N is the number of particles. The systems overall conservation of momentum restricts the set of possible phase spaces at a subsequent time. The degrees of freedom are calculated in this light. I seem to recall the degrees of freedom being 6N - 1, but this sounds a bit too simplistic...

[eyekwah]

There are supposed to be 10 dimensions (or 11, though I think it was eventually agreed that two of the dimensions were the same). I don't pretend to understand the workings of the universe though I think 10 dimensions necessarily implies 10 degrees of freedom. I think if it were so easy to traverse the other 7 dimensions like the first 3, I think we would be gods (or *the* God). Though that's a discussion for another day.

I disagree with you regarding the unvierse made from banana peels. A universe made from banana peels isn't a logical contradiction. Perhaps it doens't make sense and/or it is extremely difficult to imagine a scenario which could produce such a universe, but there is no logical contradiction here. How could a universe with banana peels possibly exist if there weren't some sort of logical contradiction? I leave that to you to answer.

They're already applying this phase space to computers. There's a new kind of bit called a q-bit which with several other such q-bits is meant to represent a number between 0 and 1. So long as the solution isn't observed, it remains a probability of being 0 and 1. The idea being that rather than searching for a solution deterministically, you use q-bits to calculate a range of probable solutions in an indeterministic fashion. The result is that it cuts down drastically on the calculation time. It's interesting stuff.

[cousinbasil]

I disagree with you regarding the universe made from banana peels. A universe made from banana peels isn't a logical contradiction. Perhaps it doesn't make sense and/or it is extremely difficult to imagine a scenario which could produce such a universe, but there is no logical contradiction here. How could a universe with banana peels possibly exist if there weren't some sort of logical contradiction? I leave that to you to answer.

There are all sorts of logical contradictions in the BPU. Each of the banana peels would either be a banana peel such as we know them, or it would not. If not, the the BPU is meaningless. If so, then each BP would consist of easily recognizable smaller units - such as cells and so forth. That being so, then it could not be a "universe made up exclusively of banana peels." You are simply recasting the square circle, impossible because it is a logical contradiction.
If the BPU is impossible as you claim - and it is impossible for some other reason than being logically impossible - what could that other reason be?

BTW, I am such an eyekwah that I just got your alias...!

[eyekwah]

For all intents and purposes, assume the BPU exists at some slice of time in the entirety of the universe. In other words, the big bang didn't explode banana peels, simply that at least at one point in time, the entire universe was composed of banana peels. It's no logical contradiction.

Such things exist in our world, albeit not as a fundamental building block, but they exist nonetheless. I say such a universe is impossible because no sequence of events, improbable or otherwise could ever amount to a universe made entirely of banana peels. Again, it's not a *logical* contradiction because the very definition of a BPU doesn't contradict itself. It's simply a situation that could not possibly arrive no matter how improbable a series of situations might be prior to the BPU.

I suppose you could argue that the mere fact that such a series of situations could not lead up to the BPU is in some complex way, a logical contradiction. If that's the case, I suppose you'd be right in that it's a logical contradiction, but you'd have to agree at that point that the set of universes without logical contradictions are trivially the same ones which are possible since you could call any such BPU universe a logical contradiction.

[cousinbasil]

Again, it's not a *logical* contradiction because the very definition of a BPU doesn't contradict itself. It's simply a situation that could not possibly arrive no matter how improbable a series of situations might be prior to the BPU.

It's a logical contradiction the same way as a "square circle" is. This is because what is implied by the word "square" and what is implied by the word "circle" (even if square is used as an adjective) are mutually exclusive. Both a square and a circle can be defined in precise terms. These terms cannot coexist for the same thing, so that thing is impossible logically.

It would be like saying A = B AND A [not-equ] B at the same time.

The BPU is impossible not because no Big Bang could eventually lead to it, but because of the reason that no initial state could lead to it. It is a logical contradiction. A BPU consists of nothing but BPs, per your definition. But a banana peel is a thing that consists of other things that are not themselves banana peels. If you define a BP as something that cannot be broken down further (and cannot combine to produce a thing with properties unlike those of a BP the way atoms can form molecules with different properties from those of the atoms themselves), then there is no logical contradiction. But then it is not a banana peel, is it? Sometimes a banana peel is just a bannana peel...

[eyekwah]

Well I thought it was evident that I meant that all the mass is composed of many ordinary banana peels. Obviously this allows for a banana peel to be composed of plant cells and other mass which cannot be called a "banana peel" in the strict sense. Likewise, a gigantic huddle of banana peels is a planet which you could argue is a logical contradiction because I said the universe is composed of only banana peels and a "planet" is not the same thing as a banana peel.

If you misunderstood, I apologize. However, you're looking for trivial ways to call it a logical contradiction but I can easily dodge them by clarifying what I meant or if necessary, by redefining an example. Give me a non-trivial demonstration of why a universe could never be composed of only banana peels which involves a logical contradiction.

Burden of proof is on you.