You find yourself in the cretaceous

[untermensche]

For a creature that perceives the world to be flat, it is also rational to say that east is one way and west is the opposite direction.

You can question my assumptions but you can't claim they are wrong because some imaginary creature with limited information makes bad conclusions.

This is about the nature of human observers in the universe.

They have a starting point with starting conditions.

Do you disagree?

It is not rational to say today happened before yesterday. .

... and irrational to say if you go east long enough, you end to the west of where you started.

Nothing irrational about moving in a circle on a sphere.

But it is very irrational to say today occurred before yesterday.

It shows one does not understand what the word before means in terms of unidirectional time.

And what is determines what can be.

Humans are temporal beings within a universe.

Now that is mysticism.

The "I" at this point in time is a collection of elementary particles that are temporarily moving along very similar paths through spacetime, roughly defined as those particles that are currently inside the volume encompassed by my skin (though whether that includes the apple I just ate or the shit I'm going to dump within the hour, or the 100 trillion bacteria in my gut, is debatable). Most of those particles have existed since shortly after the Big Bang, many have been part of the same nuclei they are in now, and a tiny minority have been part of the "I" from 30 years ago. Physically speaking, the "I" of today, the "I" of yesterday, and the "I" of 10 years in the my future are different sets of particles at different coordinates of spacetime.

You make an error of fact here.

You claim you are just the material that makes you up.

That is not factual.

You are that material in a specific arrangement with specific activity associated with that arrangement.

The Krebs cycle runs in a specific direction. It is something totally different running in the other direction and not simply the opposite of the Krebs cycle. It is something that would not occur. It would not work to try to run the cycle backwards. It can only work and be productive moving in one direction.

In what sense? If the "I" of "now" is just a collection of particles in a particular configuration, each having arrived here through its own trajectory through spacetime (including non-parallel timelines), what is to say that what applies to possible trajectories in spacetime doesn't also apply to humans?

The "I" is a specific arrangement of matter and energy. It is not just the matter and energy.

You are being a mystic when you say the matter that made you up at birth somehow contained you before you were conceived.

It is impossible for a human observer to be part of any events that occurred before they existed, at birth.

If closed time-like curves do not exist, or macroscopic entities cannot enter them, yes. But that's just another way to say "if time travel is impossible (for humans), then humans cannot travel through time." Circular reasoning doesn't cease to be circular because you employ two different formulations for the same premise.

You ignore the "at birth" part and ignore the nature and starting conditions of all observers.

Other than that you have a point.

A person must be born before they can travel down any closed curves.

They cannot have traveled down the curve before they existed.

You cannot eat a hotdog on Mars before you exist.

 

[untermensche]

A leaf can move on the surface of the river. It can move through space with limitations.

But it cannot be in the river moving until it lands on the water.

It was your analogy: You tried to argue that the non-uniform surface of a river nonetheless carries a raft forward, not backward - just like non-uniform flow of time still means that entities move exclusively forward in time.

https://www.oxfordlearnersdictionaries.com/definition/american_english/analogy

So?

All analogies have limitations.

I never claimed time was a river. Only that time and rivers both have less than flat surfaces and things move within them.

An observer is still being pushed forward by time. All of them are.

Even if a leaf can move many directions on the surface of a less than flat river.

You have a bumpy surface to time.

But no evidence an observer can negate the forward push of time on them. To go back in time would mean escaping the forward push of time.

 

[Jokodo]

You can question my assumptions but you can't claim they are wrong because some imaginary creature with limited information makes bad conclusions.

This is about the nature of human observers in the universe.

The nature of human observers in the universe cannot be discussed independently of the nature of the universe.

They have a starting point with starting conditions.

Do you disagree?

In a sense, yes. That doesn't tell us much about how those starting conditions can come about, or whether at any point, in any of the many causal chains that created the starting conditions, retroactive causality could have been involved (if the universe allows retroactive causality, that is).

... and irrational to say if you go east long enough, you end to the west of where you started.

Nothing irrational about moving in a circle on a sphere.

But it is very irrational to say yesterday occurred before today.

It shows one does not understand what the word before means in terms of unidirectional time.

That's a circular argument when whether time is strictly unidirectional is precisely what's under debate. Exactly like it would be a circular argument to say "but you're in Europe, which is east of North America where I am, and we all know that in order to get to China, I have to go west, so how can you claim that you get to China by going east" would be a circular argument if we were in a time and place where a flat earth and a roughly spherical earth were competing hypothesis.

Saying that one observer's yesterday cannot be another observer's tomorrow if there is a sense in which the two observers are synchronous sounds plausible, but whether it is true depends on the topology of spacetime. Just like it sounds plausible that one observer's east cannot be another observer's west if the first observer is already further east than the second, but whether it is true depends on the topology of earth's surface. You and I happen to know that the earth's surface is not flat. We do not know enough about the topology of time to make a definite statement on the other question, though you seem to believe you do.

You just can't give any reason beyond person incredulity. Like that flat earther.

And what is determines what can be.

Humans are temporal beings within a universe.

Now that is mysticism.

The "I" at this point in time is a collection of elementary particles that are temporarily moving along very similar paths through spacetime, roughly defined as those particles that are currently inside the volume encompassed by my skin (though whether that includes the apple I just ate or the shit I'm going to dump within the hour, or the 100 trillion bacteria in my gut, is debatable). Most of those particles have existed since shortly after the Big Bang, many have been part of the same nuclei they are in now, and a tiny minority have been part of the "I" from 30 years ago. Physically speaking, the "I" of today, the "I" of yesterday, and the "I" of 10 years in the my future are different sets of particles at different coordinates of spacetime.

You make an error of fact here.

You claim you are just the material that makes you up.

That is not factual.

You are that material in a specific arrangement with specific activity associated with that arrangement.

I pretty much said as much in the next paragraph (though I used "configuration" instead of "arrangement").

The Krebs cycle runs in a specific direction. It is something totally different running in the other direction and not simply the opposite of the Krebs cycle. It is something that would not occur. It would not work to try to run the cycle backwards. It can only work and be productive moving in one direction.

In what sense? If the "I" of "now" is just a collection of particles in a particular configuration, each having arrived here through its own trajectory through spacetime (including non-parallel timelines), what is to say that what applies to possible trajectories in spacetime doesn't also apply to humans?

The "I" is a specific arrangement of matter and energy. It is not just the matter and energy.

You are being a mystic when you say the matter that made you up at birth somehow contained you before you were born.

I'm pretty sure I didn't say that because I don't know what it means.

It is impossible for a human observer to be part of any events that occurred before they existed, at birth.

If closed time-like curves do not exist, or macroscopic entities cannot enter them, yes. But that's just another way to say "if time travel is impossible (for humans), then humans cannot travel through time." Circular reasoning doesn't cease to be circular because you employ two different formulations for the same premise.

You ignore the "at birth" part and ignore the nature and starting conditions of all observers.

There is nothing metaphysical about birth. It is a point in the web of events, linked by causal chains, that contributed to me being here and now and what I am. Another one is that bee pollinating the flower that would become the apple I ate yesterday, for example.

 

[Jokodo]

A leaf can move on the surface of the river. It can move through space with limitations.

But it cannot be in the river moving until it lands on the water.

It was your analogy: You tried to argue that the non-uniform surface of a river nonetheless carries a raft forward, not backward - just like non-uniform flow of time still means that entities move exclusively forward in time.

https://www.oxfordlearnersdictionaries.com/definition/american_english/analogy

So?

All analogies have limitations.

I never claimed time was a river. Only that time and rivers both have less than flat surfaces and things move within them.

An observer is still being pushed forward by time. All of them are.

Even if a leaf can move many directions on the surface of a less than flat river.

You have a bumpy surface to time.

But no evidence an observer can negate the forward push of time on them. To go back in time would mean escaping the forward push of time.

Which is possible if and only if there are pockets in the universe where time pushes in a different direction, like an eddy in a river. We do not know that there are, but, despite your protestations to the contrary, neither do we know that there aren't. Or rather, if you do have good evidence that there aren't, you are doing a piss-poor job at presenting it.

 

[untermensche]

The nature of human observers in the universe cannot be discussed independently of the nature of the universe.

They have no nature until they exist.

And they have a specific beginning in time.

It is a beginning within the events of the universe after many events have taken place without that observer in the universe yet.

And at that beginning an observer has certain starting conditions.

Those conditions include not being a part of any events that occurred before the observer was born.

That is a logical impossibility, not some blindness about the nature of the universe.

An observer cannot be a part of any events until AFTER that observer exists.

In a sense, yes. That doesn't tell us much about how those starting conditions can come about, or whether at any point, in any of the many causal chains that created the starting conditions, retroactive causality could have been involved (if the universe allows retroactive causality, that is).

As an absolute fact. Not in a sense.

As an absolute fact an observer has starting conditions.

They are a living thing.

They have unidirectional biological cycles and mass and a specific time of origin within the universe.

We need not look for any imaginary causal chain if the apparent causal chain can explain the existence of an observer.

The apparent causal chain is cellular reproduction. It begins with the joining of two cells.

What else would we need to explain the existence of the observer?

That's a circular argument when whether time is strictly unidirectional is precisely what's under debate.

That is not the debate.

The debate is whether it is possible to escape the unidirectional nature of time and move outside of that nature to a previous point in time then reenter the forward movement of time at an earlier time.

Thinking a human can reverse the directional nature of time is preposterous.

Saying that one observer's yesterday cannot be another observer's tomorrow if there is a sense in which the two observers are synchronous sounds plausible, but whether it is true depends on the topology of spacetime.

We are talking about what one observer can do and the conditions on every observer.

An observer has a beginning. Every one has a beginning in the chain of events called the universe. This is a limitation. An immutable limitation.

It means every observer has many events that already happened before they existed.

At their birth they cannot be a part of any events that occurred before they existed.

The only way to experience those events would be to somehow intrude into those events that occurred before they existed and change those events.

Time travel is only possible if the past can change (it can't).

There is nothing metaphysical about birth.

There is something singular and limiting about it.

It occurs at a specific time at a specific place.

And at birth an observer cannot be part of any events that happened before they were born.

Time travel is only possible if the past can change.

 

[untermensche]

Which is possible if and only if there are pockets in the universe where time pushes in a different direction, like an eddy in a river. We do not know that there are, but, despite your protestations to the contrary, neither do we know that there aren't. Or rather, if you do have good evidence that there aren't, you are doing a piss-poor job at presenting it.

You are giving an incredibly abstract and limited hypothesis about how an observer might escape the forward movement of time and move to some earlier part of time.

That observer still had a birth at a specific time. A present time for an observer existed at birth. Any past time for the observer did not contain them, at birth.

If they go to some past time they must change it since it is impossible they were a part of it prior to intruding upon it.

 

[untermensche]

My point about the Krebs cycle is an important point about biological entities and the forward movement of time.

Biological entities rely on the forward movement of time.

They cannot exist without that forward movement and cannot exist in a backward movement of time.

The Krebs cycle does not work in reverse. It would not keep anything alive if time ran backward.

 

[Jokodo]

They have no nature until they exist.

And they have a specific beginning in time.

Actually, in spacetime. If time is not a line with points, then "a beginning of time" is underdefined - you need to state the reference frame too.

It is a beginning within the events of the universe after many events have taken place without that observer in the universe yet.

That's only necessarily true if the universe has a unique timeline.

And at that beginning an observer has certain starting conditions.

Those conditions include not being a part of any events that occurred before the observer was born.

That's not a logical necessity, it's a prejudice you won't give up because you can't fathom any alternatives.

That is a logical impossibility, not some blindness about the nature of the universe.

An observer cannot be a part of any events until AFTER that observer exists.

If time is linear, yes.

As an absolute fact. Not in a sense.

As an absolute fact an observer has starting conditions.

Yes.

They are a living thing.

Yes.

They have unidirectional biological cycles and mass

Yes, and yes.

and a specific time of origin within the universe.

A "time of origin within the universe" is a notion that only makes sense if there's universal timeline. Otherwise, it's like saying "a distance from the Western rim of the world".

We need not look for any imaginary causal chain if the apparent causal chain can explain the existence of an observer.

The apparent causal chain is cellular reproduction. It begins with the joining of two cells.

Indeed. What's the logic again that tells you that in order for two cells to join, nothing like the product of their joining can have previously existed?

What else would we need to explain the existence of the observer?

A lot more. For a start, that bee must have pollinated that apple tree whose fruit I ate yesterday, otherwise I wouldn't be what I am now. My parents must have met. An asteroid must have wiped out the dinosaurs. Some kind of bacterium must have developed resistance against oxygen poisoning when the cyanobacteria upended the atmosphere with their exhausts.

That's a circular argument when whether time is strictly unidirectional is precisely what's under debate.

That is not the debate.

The debate is whether it is possible to escape the unidirectional nature of time and move outside of that nature to a previous point in time then reenter the forward movement of time at an earlier time.

That would be the debate if we knew that time is strictly, and universally, unidirectional. We don't so, so claiming that this is the only debate is making unwarranted assumptions.

Thinking a human can reverse the directional nature of time is preposterous.

Did that leaf in the eddy reverse the direction of the river?

Saying that one observer's yesterday cannot be another observer's tomorrow if there is a sense in which the two observers are synchronous sounds plausible, but whether it is true depends on the topology of spacetime.

We are talking about what one observer can do and the conditions on every observer.

An observer has a beginning. Every one has a beginning in the chain of events called the universe.

That's a reasonable way to describe things in a universe with universal, linear time. It doesn't look like we live in such a universe.

This is a limitation. An immutable limitation.

It means every observer has many events that already happened before they existed.

At their birth they cannot be a part of any events that occurred before they existed.

The only way to experience those events would be to somehow intrude into those events that occurred before they existed and change those events.

Time travel is only possible if the past can change (it can't).

There is nothing metaphysical about birth.

There is something singular and limiting about it.

It occurs at a specific time at a specific place.

And at birth an observer cannot be part of any events that happened before they were born.

Believe me when I say that we've all understood that this is what you believe. Maybe you can explain your beliefs without assuming your conclusions?

Time travel is only possible if the past can change.

Or if the past includes time travelers from the future.

 

[Jokodo]

My point about the Krebs cycle is an important point about biological entities and the forward movement of time.

Biological entities rely on the forward movement of time.

They cannot exist without that forward movement and cannot exist in a backward movement of time.

The Krebs cycle does not work in reverse. It would not keep anything alive if time ran backward.

That tells us that living beings cannot move back in time within their local reference frame. It doesn't negate the possibility that they move back relative to an outside observer's reference frame if they they find themselves in a sufficiently distorted pocket of spacetime.

 

[Elixir]

You cannot be a part of those events
You can't be in the past
You can't change the directional nature of time.

You can't be the arbiter of "can't".
It's that simple. Doesn't matter how many times you say "you can't".
YOU DON'T KNOW WHAT IS POSSIBLE

Sorry that it makes you so insecure, but that's the way it is.

Rationality can sometimes be the arbiter of what is.

Smug satisfaction that one's "common sense" is rational, is among the most common causes of the downfall of rationality.

 

[Jokodo]

Which is possible if and only if there are pockets in the universe where time pushes in a different direction, like an eddy in a river. We do not know that there are, but, despite your protestations to the contrary, neither do we know that there aren't. Or rather, if you do have good evidence that there aren't, you are doing a piss-poor job at presenting it.

You are giving an incredibly abstract and limited hypothesis about how an observer might escape the forward movement of time and move to some earlier part of time.

That observer still had a birth at a specific time. A present time for an observer existed at birth. Any past time for the observer did not contain them, at birth.

If they go to some past time they must change it since it is impossible they were a part of it prior to intruding upon it.

I asked for good evidence. Not half baked rationalizations.

 

[untermensche]

My point about the Krebs cycle is an important point about biological entities and the forward movement of time.

Biological entities rely on the forward movement of time.

They cannot exist without that forward movement and cannot exist in a backward movement of time.

The Krebs cycle does not work in reverse. It would not keep anything alive if time ran backward.

That tells us that living beings cannot move back in time within their local reference frame. It doesn't negate the possibility that they move back relative to an outside observer's reference frame if they they find themselves in a sufficiently distorted pocket of spacetime.

Yes if magic happens they can move from the moment of their birth into the magic portal and go back in time.

But they are still moving from the moment of their birth.

They cannot be in the past until after they are born and all the events of that past have occurred without them.

They are not a part of any past events at birth.

They cannot be.

Even with this science fiction called nonlinear time.

 

[untermensche]

Which is possible if and only if there are pockets in the universe where time pushes in a different direction, like an eddy in a river. We do not know that there are, but, despite your protestations to the contrary, neither do we know that there aren't. Or rather, if you do have good evidence that there aren't, you are doing a piss-poor job at presenting it.

You are giving an incredibly abstract and limited hypothesis about how an observer might escape the forward movement of time and move to some earlier part of time.

That observer still had a birth at a specific time. A present time for an observer existed at birth. Any past time for the observer did not contain them, at birth.

If they go to some past time they must change it since it is impossible they were a part of it prior to intruding upon it.

I asked for good evidence. Not half baked rationalizations.

You want evidence for what?

That a person has a birth?

And that a birth occurs at a specific moment in time no matter what magic eddies an observer runs into at a later time.

A person must exist before they can run into a magic eddy.

I need to give you evidence for that?

What evidence are you talking about?

 

[untermensche]

Rationality can sometimes be the arbiter of what is.

Smug satisfaction that one's "common sense" is rational, is among the most common causes of the downfall of rationality.

Sure.

And smugness that conjectures in physics that have no evidence to support them are true or understood is a downfall too.

 

[DBT]

Rationality can sometimes be the arbiter of what is.

Smug satisfaction that one's "common sense" is rational, is among the most common causes of the downfall of rationality.

Sure.

And smugness that conjectures in physics that have no evidence to support them are true or understood is a downfall too.

If you have never been to Sweden, going there as a tourist doesn't significantly alter Swedish history or the course of World events. The presence of a time traveler in the Cretaceous would most probably not even register.

 

[Jokodo]

I asked for good evidence. Not half baked rationalizations.

You want evidence for what?

That a person has a birth?

And that a birth occurs at a specific moment in time no matter what magic eddies an observer runs into at a later time.

A person must exist before they can run into a magic eddy.

I need to give you evidence for that?

What evidence are you talking about?

Some kind of evidence that the universe is not in not in fact stranger than we can imagine and that human intuition is a sound method to discern facts about its nature.

 

[untermensche]

Sure.

And smugness that conjectures in physics that have no evidence to support them are true or understood is a downfall too.

If you have never been to Sweden, going there as a tourist doesn't significantly alter Swedish history or the course of World events. The presence of a time traveler in the Cretaceous would most probably not even register.

You don't know Quantum Theory.

To merely observe reality changes it.

 

[untermensche]

I asked for good evidence. Not half baked rationalizations.

You want evidence for what?

That a person has a birth?

And that a birth occurs at a specific moment in time no matter what magic eddies an observer runs into at a later time.

A person must exist before they can run into a magic eddy.

I need to give you evidence for that?

What evidence are you talking about?

Some kind of evidence that the universe is not in not in fact stranger than we can imagine and that human intuition is a sound method to discern facts about its nature.

An observer still needs to be born.

And a birth is a singular event in time.

A person can only go to the past after they have been born.

And in so doing they will change that past.

Time travel is only possible if changing the past is possible.

 

[Jokodo]

Some kind of evidence that the universe is not in not in fact stranger than we can imagine and that human intuition is a sound method to discern facts about its nature.

An observer still needs to be born.

And a birth is a singular event in time.

A person can only go to the past after they have been born.

And in so doing they will change that past.

Time travel is only possible if changing the past is possible.

Or if our intuitions about the flow of time are applicable only within particular regions of spacetime but not universally so.

 

[Jokodo]

My point about the Krebs cycle is an important point about biological entities and the forward movement of time.

Biological entities rely on the forward movement of time.

They cannot exist without that forward movement and cannot exist in a backward movement of time.

The Krebs cycle does not work in reverse. It would not keep anything alive if time ran backward.

That tells us that living beings cannot move back in time within their local reference frame. It doesn't negate the possibility that they move back relative to an outside observer's reference frame if they they find themselves in a sufficiently distorted pocket of spacetime.

Yes if magic happens they can move from the moment of their birth into the magic portal and go back in time.

Like the magic that makes someone who only ever went east come back home from the west?