Which leads us to the conclusion that time could be an illusion. We have this notion, we've given it a name - time - but what we're actually tracking is change.

This just popped into my head: I always believed that animals, specifically predators - big cats especially - had a sense of time which if it isn't chronos is definitely kairos for they have to, as I initially assumed, know when to begin their chase for the selected prey animal. This, however, could be an illusion because there's the possibility that the chase begins not in a temporal context wherein the lion/tiger, in its mind, comes to the conclusion that "yes, this is the right moment to begin my chase" but what actually goes on in the lion's/tiger's mind is a spatial calculation as in "this is the optimum distance for a successful chase". The two - temporal vs spatial reasoning vis-à-vis hunting - appear to be indistinguishable. The question that naturally arises is, can this be true of us too? In the simplest sense, could time be space? :chin:

Hypothetically yes but the laws of physics as we know it do not allow travel into the past.

Some theories, most notably special and general relativity, suggest that suitable geometries of spacetime or specific types of motion in space might allow time travel into the past and future if these geometries or motions were possible.

https://en.wikipedia.org/wiki/Time_travel

Time travel into the past It is therefore theoretically not possible, but due to lack of our knowledge about universe your hypothesis is not completely invalid.

In the simplest sense, could time be space? — TheMadFool

I would say no because then we can assume "non movement" trough space as stopping (or slowing down) the time which isn't the cause.

A question may arise, what about inanimate nature? it is subject to time as well.

I would say no because then we can assume "non movement" trough space as stopping (or slowing down) the time which isn't the cause.

A question may arise, what about inanimate nature? it is subject to time as well. — SpaceDweller

Imagine yourself deer hunting with a compound bow. You see a deer but you realize it's not in range. You, as quietly as possible, close in on the hapless deer. It's now inside your bow's kill zone. What goes on inside your head? Do you tell yourself, "this is the right moment to release my arrow"? or do you think, "this is the right distance for a killshot"? Could a disinterested observer figure out which of the two thoughts mentioned above determined your actions? If yes, how? If no, I rest my case. Sorry for repeating myself but I needed to clarify things to myself and to you too.

"this is the right distance for a killshot?" — TheMadFool

I may say "this is the right distance for a killshot?"
Isn't my thinking in this sense merely my judgement? a mental ability.

How does my judgement about distance affect time?

We know measuring distance is not same as measuring time because of speed factor (ex. the speed of my arrow), therefore we could also say "this is the right moment to release my arrow?"
But doesn't this depend on relative speed of the arrow and the speed of the deer?

Isn't relative speed affecting both scenarios?

We know relative speed can make our perception about time wrong, did you ever walk train station in opposite direction of the moving train?
You must have noticed the station moving and the train staying in place right? :smile:

Does the train station example affect time or distance or something else? and if so why?

:ok: Just a random thought of mine. I suppose it's facile enough to be dismissed from the outset.

So then if we took a "snapshot" of this very moment with it's totality, that being: — unintelligiblekai

You cannot, but you can imagine it. Time is what is and what is unfolding. There is no traveling in time, only change that we feel, like molding a piece of clay.

what a nice thought pattern you had. I Suppose to your animal wonderings we could assume that some animals, have a biological system like ours that regulate sleep patterns. They also experience hunger and it could be through their routine that their appetite begins at certain periods of the day.

Yes, had same idea few years ago it is entirely possible we do similar thing in computers when we do a "save" or "checkpoint" the only thing is even if knew all variables needed for a specific state of a universe, how do we push them to atoms? I like to call it state traveling much more fitting and theoretically speaking once we invent a machine to capture and push state through whole wide universe we would be able to calculate past based on it to its correct form then universe would become huge game where we change variables to state we need, sounds fun :)

would that not be considered time travel? — unintelligiblekai

Yes that is correct form of "time" traveling, it's just hollywood concept for people to imagine it

What about sending a signal into the past or future rather than a macroscopic object? This seems more possible, less impeded by classical physics, if a form of energy wave that transmits information fast enough is discovered. What if we could turn on a device and get detailed engineering blueprints from thousands of years in the future or receive messages from distant parts of the galaxy?

how do you believe a signal could be sent to the past?

It would have to be via a kind of wave that is independent of electromagnetic matter, maybe dark matter, perturbing faster than the speed of light or penetrating more deeply into reality's underlying structure. Whether a technology of time traveling waves is possible depends on the orientation of thus far unknown matter to known matter and the logistics of generating these waves, but it intuitively seems to me as if some mechanism of this type must exist. Maybe studying the way brains transmit energy would be a good start, the technology could initiate with a more substantive model of near instantaneous and retroactive causality in nature. I think its more likely we can obtain a digitalized signal from the future because there are no receiver devices in the past. Of course you have to make sure that it wouldn't leave a path of devastation in its wake, but a harmless incarnation probably exists.

Time doesn't exist. What we call time is a contract between all humans and its societies in this world. It is only memories we all have about past events, and people seem confuse the past memories as time. There is only intervals, but nothing flows or moves. It is just illusion of memories and imagination.

For instance, a society or country can make new time contract that from tomorrow, it will be year 0, and a day will be 40 hours, and a month will be 100 days, and run it like that. I think historically Cambodia had done it sometime in 1970s. And initially people will get confused or feel chaos on the time perception, but they will get used to it.

So, yes time travel is possible, but only in memories and imaginations and the movies. No, it is not possible in real life.

What we have is eternal present called "Now", from which no existence can escape until their consciousness fades away.

What about sending a signal into the past or future rather than a macroscopic object? — Enrique

This is a really good movie incorporating your idea: Prince of Darkness

I think time travel is possible, the past will include the time travel event as part of history. For example, you travel back to 1870, wait for a few minutes and then come back. People will see you appear for a few minutes and disappear.

All causal events stemming from the time travel will be recorded as having an unexplained cause.

I have read some stories of alleged time travel, and it seems to be possible to fit them into a consistent picture of the universe and reality.

https://www.indiatimes.com/culture/who-we-are/7-real-accounts-of-time-travel-that-ll-leave-you-questioning-everything-258251.html

would that not be considered time travel? — unintelligiblekai

I don't think that would be considered time travel, you would still be moving forward through time while you change the environment. Theoretically, if you also knew the exact placement of every particle in the past you could recreate a past situation, but recreation would not be traveling back and viewing it in time it actually happened. The only way to see into the past would be to somehow transfer yourself to a far distant place with a telescope to view earth as it was in the past. Also you can already travel forward in time by going very fast.

yes, effectively, if you could match the physical arrangement of a previous period in time, there's not much distinguishing that from time travel I suppose. I mean, to do it fully you'd have to reposition every atom in the universe, but you could I suppose do it at just, say, the scale of a planet and it would be good enough.

It's of course not practically possible.

If you consider it in terms of photons time travel is not possible.
Suppose on Jan 1, 2000, there is a light source at A. Photons travel to B.
Now a time traveler leaves on Jan 1, 2010 and appears on Jan 1, 2000, at C, the mid point between A and B.
The time traveler blocks the light and it does not reach B.
So, does the light reach B or not?

It still wouldn't be time travel. It would be recreating the past in the future. Just like recreating a natural diamond perfectly in a lab, doesn't make another natural diamond, rather it is a natural appearing lab grown diamond.

It still wouldn't be time travel. It would be recreating the past in the future. Just like recreating a natural diamond perfectly in a lab, doesn't make another natural diamond, rather it is a natural appearing lab grown diamond. — LuckyR

This. You can't go to the past. You can only recreate a setup of matter and energy that existed in the past. Once you did, it would then continue identically as it did in the past unless any specific alterations were made.

According to trusty Wikipedia:

Time travel is the hypothetical activity of traveling into the past or future. Time travel is a widely recognized concept in philosophy and fiction, particularly science fiction. In fiction, time travel is typically achieved through the use of a hypothetical device known as a time machine.

The idea of time travel is more easily understood in terms of time travel to a past or earlier time than the present time. Let's say that a time machine was first invented at the present time, tn, and is to be used to return to an earlier time, te. This means - prior to any use of the newly invented time machine - that there is an "original" version of time, te, which is pre-time-travel (and contains no time traveller). Once the time machine is used, there will then be a second version of that same time, te, which is post-time-travel and contains the addition of the time traveller. That is, the use of the time machine and the introduction of time travel means that a second timeline branches off and exists concurrently with (or as a parallel universe to) the first "original" timeline. This is required in order for the concept of time travel to make sense. If you want to use the time machine to go back and kill Hitler, then there needs to be an original timeline in which Hitler exists and will do, is doing or has done his evil deeds before anyone can go back in time to kill him.

The same holds for time travel to a future time, assuming that the events of the "original" future timeline would have played out a particular way prior to any time travel.

I don't really understand the argument that you must recreate the past exactly as it already did occur or that you cannot logically go back in time to kill your grandfather. These assume that there can only be one timeline, original or otherwise. But I don't think that assumption is consistent with the logical concept of time travel.

Impossibility of time travel seems to be one of the universally necessary truth. I am not sure if it would be even possible in a possible world. If one believed in the multiverse which runs on different times, would it be then imaginable in one them? But multiverse itself is a theoretical hypothetical idea, which is not proven to be existence yet.

Impossibility of time travel seems to be one of the universally necessary truth. — Corvus

Let's suppose I build a time machine and use it to travel to a time before my birth. What makes it impossible? I take it your view is based on the immutability of a single timeline, but that's never been proven and I can find no good reason why it must be assumed.

If one believed in the multiverse which runs on different times, would it be then imaginable in one them? — Corvus

It has been imagined in numerous works of fiction, so it does not appear to be unimaginable.

But multiverse itself is a theoretical hypothetical idea, which is not proven to be existence yet. — Corvus

The question of the OP is whether time travel is hypothetically possible. I don't see why not.

Time travel backwards seem to be mostly impossible due to the fact that reality collapses into a single point at each moment in time. If you were to turn the arrow of time, there are no probabilities that can fraction out of events that happen, there's no causal links that make sense. In essence it would lead to a disruption of every point in reality. The only possible way is if the multiverse is true, if all probabilities has their own branch, but then there's no point in going back in time to do anything as you cannot change the future you came from. It would be closer to traveling to other universes rather than specifically traveling back in time. And any change would only just fraction into new branches into such complexity that there's no ability to "go back" to any meaningful timeline since there's no actual timelines that exist.

It's basically like seeing white noise on an old TV, that's the chaos of probabilities and then all those points in that white noise collapse into a single point. If you go back in time, which point is the correct point that you would define was the "true" past one? It's an absurd attempt as all points are true until it collapses into just the one.

What makes it impossible? I take it your view is based on the immutability of a single timeline — Luke

Why would you assume that? That's very abstract. How about something more simple: it's impossible, as far as we can tell, because there's no known physical phenomena that could allow us to do it.

Why would you assume that? — flannel jesus

It's based on what I've read of time travel paradoxes such as the Grandfather paradox.

Why would you assume that? That's very abstract. How about something more simple: it's impossible, as far as we can tell, because there's no known physical phenomena that could allow us to do it. — flannel jesus

Isn't that just saying that we don't have the technology or knowledge to time travel? This doesn't mean that it is hypothetically impossible.

Let's suppose I build a time machine and use it to travel to a time before my birth. What makes it impossible? I take it your view is based on the immutability of a single timeline, but that's never been proven and I can find no good reason why it must be assumed. — Luke

It seems the whole imagination has been based on the wrong assumption that the past and future are some sort of geographical destinations such as Tokyo, NY, Paris ... etc, which is not.

Another wrong assumption is that time is some type of physical distance laid out like a road or highway.

The reality is that time is an illusion, and there are only Durations (already proved and declared by Newton), and the past and future are concepts, not geographical places you can arrive at or depart from.

You cannot travel into a place where the destination doesn't exist. We are all nailed into the present until deaths under the universal law.

It has been imagined in numerous works of fiction, so it does not appear to be unimaginable. — Luke

The question of the OP is whether time travel is hypothetically possible. I don't see why not. — Luke

Sure one can imagine anything, but we are just letting them be aware that it is imaginable (at stretch), but impossible in reality from the logical and metaphysical point of view. :)

It seems the whole imagination has been based on the wrong assumption that the past and future are some sort of geographical destinations such as Tokyo, NY, Paris ... etc, which is not.

Another wrong assumption is that time is some type of physical distance laid out like a road or highway.

The reality is that time is an illusion, and there are only Durations (already proved and declared by Newton), and the past and future are concepts, not geographical places you can arrive at or depart from. — Corvus

What makes these assumptions wrong? What argument supports your assertion that times are not "geographical places you can arrive at or depart from"?

You cannot travel into a place where the destination doesn't exist. We are all nailed into the present until deaths under the universal law. — Corvus

Whatever time I am at is the present time for me. Therefore, if I were to build a time machine and use it to travel back 100 years, then it would be the present time for me when I depart today and still the present time for me when I arrive 100 years ago.

What makes these assumptions wrong? What argument supports your assertion that times are not "geographical places you can arrive at or depart from"? — Luke

Can you travel into your happiness or hopes? There is no such a place as the past or future. There are geographical places such as the countries, cities and towns, not the past or future. You cannot escape the present. It is a universal law, which the whole universe and its contents must abide by.

Whatever time I am at is the present time for me. Therefore, if I were to build a time machine and use it to travel back 100 years, then it would be the present time for me when I depart today and still the present time for me when I arrive 100 years ago. — Luke

And you will be waking up from your dream or imagination. :D