Time is normal in any frame of reference. It is only relative compared to other frames of reference.

That's true, the "Speed" of light isn't actually a speed, but rather a constant.

Speeds are additive, me jogging 10 miles an hour on an airplane that's traveling 400 miles an hour makes my total speed 410 mph relative to some point on Earth.

Light on the other hand is a constant. If you flash a light while jogging 10 mph on an airplane going 400 mph, the speed the light travels is actually still just c (the constant of light) -410 mph (to adjust for the base speed relative to the constant) light is more of a structural limit than a speed.

@EnPassant gave a terse but entirely correct reply.

From my frame, would that mental “song” appear stretched out in time? — RogueAI

Yes. That's dilation, a coordinate effect. It means that from their frame, your mental song would be stretched out. 'Appear' is a loaded word since Doppler is relevant to appearances, but not relevant to time dilation. To cancel this out, I'm assuming this speedy person being observed is moving tangentially to your location.

Would it unfold more slowly to an outside observer, similar to time dilation effects?

There are no outside observers, at least not in the sense of outside of spacetime.

And would anything like a Doppler-style distortion apply

If he's moving directly towards you, Doppler effect is stronger than dilation, and his process would appear to be faster than yours. This has fooled even professional astronomers who have measured objects moving towards us to appear to be reducing the distance to us at a rate greater than c. That's Doppler effect.

I’m trying to understand how (or whether) relativity meaningfully applies to subjective mental events like imagined music, not just external physical actions.

Imagined music is just another process that takes time, same as say watching a clock. Humans are in no way special in how relativity treats any observed process.

the "Speed" of light isn't actually a speed, but rather a constant. — DifferentiatingEgg

It is expressed as a speed (not a velicity, which is frame dependent, even for light). Yes, it's a constant, and relativity theory posits (without proof) that light moves at this speed relative to any inertial frame. Note 'inertial': It can moves at different speed relative to non-inertial frames, so say light sent to the moon and back (they have reflectors up there for that) does so at slightly faster than c as measured by us.

Speeds are additive, me jogging 10 miles an hour on an airplane that's traveling 400 miles an hour makes my total speed 410 mph relative to some point on Earth.

True under Newtonian physics, but not relativity. The speeds you mention are so slow that it's really close to 410, but not exactly.

If you flash a light while jogging 10 mph on an airplane going 400 mph, the speed the light travels is actually still just c (the constant of light) -410 mph (to adjust for the base speed relative to the constant)

This is flat out wrong, in any frame. It moves locally at c relative to you, the plane, or the ground.

Time is normal in any frame of reference. — EnPassant

What does "normal" mean? That it flows at its normal 1 second per second rate?

There are no outside observers, at least not in the sense of outside of spacetime. — noAxioms

I'm pretending we have a God's-eye view outside of space-time.

I’m trying to understand how (or whether) relativity meaningfully applies to subjective mental events like imagined music, not just external physical actions. — RogueAI

If mental processes are independent of neural processes then they ought to be unaffected by the relativity of velocities. If they are not independent of neural states then they ought to be affected. Under the affect of psychedelics time dilation is a common experience, but that is an altering of the subjective sense of time.

Suppose I could somehow observe their inner mental activity directly. — RogueAI

The idea of someone observing someone else's subjective sense of time makes no sense.

perhaps the way I expressed it was poor, but what I'm saying is the light is not going at c+410 mph. That's how time dialtion works... the closer to the constant the less time you experience.

What does "normal" mean? That it flows at its normal 1 second per second rate? — RogueAI

Normal means what the first postulate of relativity means: All the normal laws apply in any inertial frame, which means there cannot be a local test for your motion. So regardless of where you are or how you're moving, everything appears 'normal' to you. Yes, time phenomenally appears to flow at its normal 1 second per second, for everybody.

I'm pretending we have a God's-eye view outside of space-time. — RogueAI

Since time is part of the universe (and not something that contains the universe), the God view isn't in time at all, and thus there is no perception of change anywhere. Also, since light cannot leave the universe, none of it gets to this god, so it isn't especially a 'view' in the sense that we have one.

If mental processes are independent of neural processes then they ought to be unaffected by the relativity of velocities. — Janus

I think the sort of dualism you suggest here is incompatible with relativity theory, which blatantly says that you can't tell if you're 'moving fast'. For instance, relativity says that if you fall into a large black hole, you cannot tell when you've crossed the event horizon. What you're suggesting is more like the experience of your body stopping as all physical processes come to a halt as the EH is approached. This would falsify all of 20th century physics, requiring a 3rd interpretation. Not even the absolutists predict that experience, regardless of one's philosophy of mind.

The idea of someone observing someone else's subjective sense of time makes no sense.

I agree, but based my reply on an assumption of mental states being in sync with (if not just being) neural states. If they're two different things that got out of sync, there would be a test for absolute motion. Your arms would be hard to move. You'd not be able to understand speech. You'd probably die if your mental states are in any way involved in life support, like say choosing to eat.

Example: Right now you're moving at ~0.997 c relative to some muon, which is part of the reason you can get to that muon before it decays in only a couple mircoseconds. This insane speed does not affect your mental abilities at all. You don't notice.

what I'm saying is the light is not going at c+410 mph. That's how time dialtion works... — DifferentiatingEgg

That's not how time dilation works.
Light moves locally at c relative to anything. So to compute light relative to the ground in your frame in the plane, you'd have to use the velocity addition formula:

sum = (v+w) / (1 + vw/c²) where v is c and w is 410

c + 410 ./ (1 + 410/c) = c

I didn't even need to bother with units to do that.

If mental processes are independent of neural processes then they ought to be unaffected by the relativity of velocities. If they are not independent of neural states then they ought to be affected. — Janus

This was my initial thought. But, funnily enough, I also went straight to psychedelic experience to note that this is perhaps simple illusion. That said, I can't see a way to litigate that. It's possible that if subjective experience isn't 1:1 eiwth neural activity that psychedelics invoke a similar effect to close-to-light-speed travel.

Yes.

I’m trying to understand how (or whether) relativity meaningfully applies to subjective mental events like imagined music, not just external physical actions. — RogueAI

Time dilation is possible within mental level. You can even travel to the past in your mental world using your own memory and imagination. But it is impossible to do so in external physical world.

literally what I've been saying, Light isn't technically a speed because you don't use velocity. So it's better to not think of it in the sense of speed. Its a RELATIVE CONSTANT (Hence I mentioned that, ty)

adjust for the base speed relative to the constant — DifferentiatingEgg

I think the sort of dualism you suggest here is incompatible with relativity theory, which blatantly says that you can't tell if you're 'moving fast'. For instance, relativity says that if you fall into a large black hole, you cannot tell when you've crossed the event horizon. What you're suggesting is more like the experience of your body stopping as all physical processes come to a halt as the EH is approached. This would falsify all of 20th century physics, requiring a 3rd interpretation. Not even the absolutists predict that experience, regardless of one's philosophy of mind. — noAxioms

I agree, but based my reply on an assumption of mental states being in sync with (if not just being) neural states. If they're two different things that got out of sync, there would be a test for absolute motion. Your arms would be hard to move. You'd not be able to understand speech. You'd probably die if your mental states are in any way involved in life support, like say choosing to eat. — noAxioms

Yes, I agree that dualism is unsupportable. If we were traveling at speed close to c, aging of our bodies and all its physical processes would, according to the theory, greatly slow down. If our minds were independent of, and unaffected by, physical processes, and proceeding at their "normal" rate, then our subjective experience of mental processes would, presumably, seem vastly speeded up, which seems absurd.

Suppose I could somehow observe their inner mental activity directly. Imagine they’re playing a song in their head — RogueAI

Not possible thing to do. The premise is false. Not accepted.

From my frame, would that mental “song” appear stretched out in time? — RogueAI

No.

No. — Corvus

Why not? it's like when you play a 45 at 33 1/3.

Why not? it's like when you play a 45 at 33 1/3. — Metaphysician Undercover

Replayed songs are physical - the speed of the motor regulates it. Unless you change the speed of the record player or digital sampling speed (in case the music is replayed digitally), the song doesn't appear stretched in time.

You can hear the song stretched in time in your mind, if your imagination can do it. But you cannot access the other folks mind, hence you wouldn't know what song is being played in his/her mind.

Replayed songs are physical — Corvus

isn't the firing of neurons, which constitutes the playing of the song in the mind, something physical as well? It doesn't happen at the speed of light, because it occurs through a physical medium. So wouldn't time dilation slow down that activity?

But you cannot access the other folks mind, hence you wouldn't know what song is being played in his/her mind. — Corvus

Consider, you could have an analyzing system hooked up to the person's brain. The person tells you i am playing Social Distortion's "I was Wrong" in my mind, and you observe the corresponding neural activity. Then, whenever you see an exact replication of that physical activity you know the person plays that song. From a different frame of reference, would time dilation apply? You might see the same activity slowed down.

isn't the firing of neurons, which constitutes the playing of the song in the mind, something physical as well? It doesn't happen at the speed of light, because it occurs through a physical medium. So wouldn't time dilation slow down that activity? — Metaphysician Undercover

But let's say your neural activity was slowed down, either through temperature or chemical or some interference. Does that mean the song playing in your head would slow down too, like "when you play a 45 at 33 1/3"? I don't think it works like that.

Yes, I agree that dualism is unsupportable. If we were traveling at speed close to c, aging of our bodies and all its physical processes would, according to the theory, greatly slow down. If our minds were independent of, and unaffected by, physical processes, and proceeding at their "normal" rate, then our subjective experience of mental processes would, presumably, seem vastly speeded up, which seems absurd. — Janus

This only invites confusion, I am afraid. At any given time, we are moving at a speed close to c in some reference frame. And, at that same time, we are not moving at all in some other reference frame. A key aspect of the subjective experience that no one would deny is that it has a point of view that is collocated with the body. That gives it a reference frame - specifically, the comoving reference frame (aka the proper frame), in which there cannot be any time dilation effects on our own body (unless said body is being violently torn apart!)

isn't the firing of neurons, which constitutes the playing of the song in the mind, something physical as well? It doesn't happen at the speed of light, because it occurs through a physical medium. So wouldn't time dilation slow down that activity? — Metaphysician Undercover

The problem is we don't know if the firing of neurons are the playing of the songs in the mind. If they are, still we don't know which neurons and what type of firing are related to the song playing, in what manner and ways.

and you observe the corresponding neural activity. Then, whenever you see an exact replication of that physical activity you know the person plays that song. — Metaphysician Undercover

Again, there is no concrete evidence or working details proving the observed neural activity is the person's playing the song. Isn't it your imagination which links the neural activity to the song in your friend's mind? It is possible to imagine it of course, but it is not demonstrable or provable with intelligible evidence, is it?

If someone were traveling close to the speed of light relative to me... — RogueAI

From their frame of reference it's you who is traveling close to the speed of light. Are your thought processes slowed in respect to the movement of your body?

What your thought experiment shows is a misunderstanding of the issue. You continue to suppose some frame of reference that is stationary in an absolute sense.

Apparently you misread what I wrote. I had in mind the commonly imagined scifi scenario, where you are traveling at close to the speed of light and all processes. including bodily processes, are slowed down such that you are aging much more slowly than those who remain on Earth.

I was attempting to point to the absurdity of thinking that the bodily processes could be slowed down while the mental processes continued at the "normal" speed, which is also to point to the absurdity of thinking that the mental processes could be independence of the bodily. It would save wasted time if people read more carefully.

You continue to suppose some frame of reference that is stationary in an absolute sense. — Banno

Many of the posters are presuming absolute frames: Not sure if RogueAI is one of them since he at least added 'relative to me'.

...the closer to the constant the less time you experience. — DifferentiatingEgg

If we were traveling at speed close to c, ... — Janus

... invoke a similar effect to close-to-light-speed travel. — AmadeusD

It doesn't happen at the speed of light, because — Metaphysician Undercover

I had in mind the commonly imagined sci-fi scenario, where you aretraveling at close to the speed of light and all processes. including bodily processes, are slowed down such that you are aging much more slowly than those who remain on Earth. — Janus

sci-fi scenario, where you aretraveling at close to the speed of light — Janus

Nothing has a traveling speed. Speed is relative to something else. Every object is stationary in its own frame. Earth is traveling at near c relative to the object I mentioned in my prior post, and yet you don't experience time running slow, which would be a violation of the first premise of relativity, and also a violation of the premises (whatever they are) of an absolutist interpretation such as LET.

SophisticCat and Banno got it right:

At any given time, we are moving at a speed close to c in some reference frame. — SophistiCat

From their frame of reference it's you who is traveling close to the speed of light. — Banno

Suppose I could somehow observe their inner mental activity directly. Imagine they’re playing a song in their head — RogueAI
Not possible thing to do. The premise is false. Not accepted. — Corvus

Not directly, sure, but you still have indirect access. Supposedly a person could be doing the Macarena dance to the music playing only in their mind. Positing that they would not be in sync is preposterous (try it). So given correlation, yes, you have indirect access to the tune in somebody's mind.

isn't the firing of neurons, which constitutes the playing of the song in the mind, something physical as well? — Metaphysician Undercover

Under certain dualist views, the firing of neurons does not constitute mental song playing. They're correlated, but supposedly not causal.
Them getting out of sync due to dilation would violate that correlation.

The problem is we don't know if the firing of neurons are the playing of the songs in mind. — Corvus

It really doesn't matter. All neural activity is subject to physical time treatment of relativity.

Yes, I agree that dualism is unsupportable. — Janus

If mental processes are independent of neural processes then they ought to be unaffected by the relativity of velocities. — Janus

Under property dualism, mental activity is just a different property of normal matter, which is subject to relativistic effects. Under substance dualism, where the substance is something in the vicinity of the being experienced, it moves, and thus the same rules apply. So what does that leave? If the mind is totally external to the universe (BiV for instance, several forms of 'souls', etc), the mind is external to the universe, and works more like a moving spotlight in that which it experiences. But such a view is necessarily either solipsistic or epiphenomenal since one cannot stay in sync with other minds. Contradictions abound, but not under most forms of dualism.

That's how time dialtion works... the closer to the constant the less time you experience. — DifferentiatingEgg

This violates all the premises of relativity, which states that you experience the same flow of time regardless of your motion, which is always by definition stationary in one's own frame.

Light isn't technically a speed because you don't use velocity. — DifferentiatingEgg

I'm suspecting you don't know the difference between speed and velocity since the statement makes no sense.

I had in mind the commonly imagined sci-fi scenario, where you are traveling at close to the speed of light and all processes. including bodily processes, are slowed down such that you are aging much more slowly than those who remain on Earth. — Janus

Again, the ship is always stationary in its own frame, and while inertial, it is the Earth inhabitants that age more slowly. The reason it works out is because the ship is not always inertial, so it takes a shorter path (intervals as integrated along all the relevant worldlines) through spacetime than does Earth.

Consider:

Suppose I could somehow observe their inner mental activity directly. — RogueAI

Such an observation would be mediated by a signal from observed to observer. That signal is either subject to the Lorentz transformation, in which case the time dilation takes effect, or it isn't, in which case there is an absolute frame of reference.

So 's hypothesis does assume an absolute reference frame in presuming frame-independent access to temporal structure. It adopts a privileged temporal standpoint.

Nothing has a traveling speed. Speed is relative to something else. Every object is stationary in its own frame. Earth is traveling at near c relative to the object I mentioned in my prior post, and yet you don't experience time running slow, which would be a violation of the first premise of relativity, and also a violation of the premises (whatever they are) of an absolutist interpretation such as LET. — noAxioms

Unless I am mistaken, the theory says that if you traveled at the speed of light to some distant star and then returned, those on Earth would have aged much more than you. In that scenario Earth is the stationary, "normal" frame and the starship the one at great speed relative to it.

So what does that leave? If the mind is totally external to the universe (BiV for instance, several forms of 'souls', etc), the mind is external to the universe, and works more like a moving spotlight in that which it experiences. — noAxioms

It is merely a conceptual matter. If traveling at speed close to c slows down bodily processes relative to those who remain on Earth and mind were completely independent of matter then presumably the slowing down would not apply to the mental processes. It is a ridiculous conversation anyway because mental processes cannot be independent of bodily processes. Also no one has ever, or probably ever will be able to, do the experiment.

Again, the ship is always stationary in its own frame, and while inertial, it is the Earth inhabitants that age more slowly. The reason it works out is because the ship is not always inertial, so it takes a shorter path (intervals as integrated along all the relevant worldlines) through spacetime than does Earth. — noAxioms

It is very simple―do you believe that if someone could travel in a vessel at near light speeds and returned to earth in say twenty years that they would have aged more or less than those on Earth? I believe the standard view is that the traveler would have aged much less.

The theory says that if you traveled at the speed of light to some distant star and then returned, those on Earth would have aged much more than you. In that scenario Earth is the stationary, "normal" frame and the starship the one at great speed relative to it. — Janus

The twin paradox is a result of the relative acceleration of the traveler. The OP is only asking about inertial frames of reference. You are adding an unhelpful complication.

If someone were traveling close to the speed of light relative to me, special relativity says their physical processes would appear slowed down from my frame — movements, reactions, even neural activity. That part makes sense when thinking about observable behavior. — RogueAI

Their physical processes cannot be observed from my frame until they return. Then I would see that their physical processes had been much slower than mine as evidenced by their relative youthfulness― assuming, that is, the correctness of the theory.

The other question as to the speed of their mental processes could not possibly be established other than, if at all, by asking them. Also, the idea that their mental processes "movements, reactions, even neural activity" could be slowed down relative to Earthers, while their mental processes could remain the same speed as the Earthers' just seems absurd.

If their mental processes remained the same while their physical processes (although seeming normal to them) were slowed down, then presumably, as I said already, their mental processes would seem speeded up to them. That just seems impossible. So, I think that question is really a non-question.

So I have been addressing the question and your claim that I am adding an unhelpful complication seems completely unfounded.

Their physical processes cannot be observed from my frame until they return. — Janus

Watch them on TV.

Watch them on TV. — Banno

Good point (how did I miss that?), but the video data from them would presumably be slowed down too relative to us. So the question then is whether their physical movements would would look slowed down to us or look normal. I can't answer that.

:wink:

It would appear slowed down.

That's what he equations say, and what empirical observation supports.