Halc

On 5/3/2024 at 11:17 PM, Mordred said:

found it I finally recalled it was a series of Black star research

"Irreversible gravitational collapse: black stars or black holes?"

The paper calls them 'black stars' and seems to posit a complete lack of event horizon, and that the matter all piles up just outside where the EH would be. This is very similar to Schmelzer's alternative generalization of LET (relativity, but denying both premises of SR).  https://arxiv.org/pdf/gr-qc/0001095

He calls the 'frozen stars' since all the matter piles up outside the nonexistent EH. It's a presentist interpretation of relativity, and it equate absolute time with coordinate time.

Just my thoughts. The alternative is that the matter gets 'inside' and is somehow prevented from going 'forward' which is the same as positing that if you put enough force on matter, you can push it into the past where there's more room.

On 5/4/2024 at 12:30 AM, pzkpfw said:

What do you mean by "binary light frequency"?

For instance, yellow-orange laser light has a frequency of about 5x10**14 Hz. The binary light frequency is equivalently 1x10**110001 Hz.

How this makes a difference is of course a mystery, but adding mirrors to the situation is just going to add to the delays since the path is less straight.

On 5/4/2024 at 12:30 AM, GregJones said:

amazingly someone replied via the radio station having calculated how long it would take

Yea, about 6 to 45 minutes depending on how far away Mars is at the time. 6-45 minutes later is not 'before it was sent'. Zero justification for the suggestion otherwise has been given.

1 hour ago, Mordred said:

so you googled a bunch of answers so tell me google what happened to the mass of the collapsing star then.... can you answer that or did it simply disappear. That is directed at google not you lol . Would you like to see equations that directly relate to the density term in regards to the collapsing star?

The collapsing star is a dynamic state, and quite different from a free-falling object. There's dense stuff, and then not even Pauli-exclusion can support it.  OK, so there's even more squish, at least at first. A spatial dimension rotates and is replaced by time, and that time dimension is bounded. What was the time dimension rotates out to a spatial one, one with nearly infinite extension at that. Lots of new room to spread out, but the causal light cones don't allow arbitrary travel down this big space, so I cannot say the compression ends.

An example of the space available inside a black hole, Sgr-A and the black hole at the center of Andromeda share a common singularity. They're the same black hole, a region of 4D spacetime bounded by a 3D event horizon hypersurface, and in that case, the same (connected) hypersurface. It's only in a slice of coordinate space at a given time that the one object has multiple cross sections, manifesting as a pair of black holes to us, for now.

None of the above is particularly an answer to the question of if there is compressed matter in an established black hole. In coordinate time, yes, it's very dense, but that's more like length contraction than pressure. None of the matter actually reaches the event horizon in coordinate time, and yes, in that state, it (the original collapsing star matter) is very much under compression.

1 hour ago, Mordred said:

If Victor Toth stated that then he only looked at the vacuum solutions of the interior  and ignored the coordinate assigned for the singularity R=0. Not surprising though most articles tend to ignore that part as no one feels the singularity condition should exist.

The singularity condition exists, but isn't described, precisely because the physics there is singular, sort of like asking what the perspective of a photon is like.

1 hour ago, Mordred said:

I have another related article that suggests that the BH may simply be a neutron star that has collapsed just beyond its EH but is still present.

Got a link? That sounds like pop nonsense. Is it peer reviewed?

1 hour ago, Mordred said:

you can in fact have extremely high density and still be a vacuum solution with incredibly high temperature and density.  Vacuum describes a pressure term.  Its not the energy density

That makes more sense. Still, to be matter, it has to persist, no?

1 hour ago, Mordred said:

just to add the singularity at r=0 is a true singularity it cannot be removed by a change in metric choice. The event horizon itself is often described as a singularity condition however that is a coordinate singularity and not a true singularity.

Agree to all. There's also a naked singularity. You can for instance just keep dropping electrons into a black hole until the charge is more than the gravity and no more (isolated) electrons can be added by any means. Similar issues if the infalling matter adds too much angular momentum. A given mass can only have so much of that. These are examples of frame independent singularities not obscured by the coordinate singularity of the EH.

1 hour ago, Mordred said:

google is useful but unless your aware of other factors getting good answers can often mislead down the wrong google pathway.

Ditto with the LLM answers, which is just massaged google results. Anyway, thanks for the post. Good informative stuff in there.

1 hour ago, Mordred said:

however the equations do lead to the infinite density singularity which everyone agrees is the issue regarding the singularity condition

The equations are how everybody knows. No links were provided, so I googled the question and the first 8 hits (NASA, Smithsonian, various you-tubes, reddit) all suggest matter is compressed without bound. Much of this list of bad hits is due to my search terms of "black hole infinite density".

First correct answer came from of all places Quora, a site known for severe wrongness of replies.  Question was: Do black holes have infinite density?  Answer by Toth:

"The equations that describe some of the simplest black hole solutions, including the Schwarzschild black hole are (drum roll, please)… equations of general relativity in the vacuum.

Yes, that’s right. The vacuum. There is no matter. The density is zero everywhere. The Schwarzschild solution is the simplest, spherically symmetric, static vacuum solution of Einstein’s field equations."

Next hit was probably the most respectable forum I can name.

https://physics.stackexchange.com/questions/246061/are-black-holes-very-dense-matter-or-empty

Rennie (I think) replies specifically about the Schwarzschild metric, which wasn't technically the question:

"The archetypal black hole is a mathematical object discovered by Karl Schwarzschild in 1915 - the Schwarzschild metric. The curious thing about this object is that it contains no matter. Technically it is a vacuum solution to Einstein's equations. There is a parameter in the Schwarzschild metric that looks like a mass, but this is actually the ADM mass i.e. it is a mass associated with the overall geometry."

The Kerr metric is also a vacuum solution, which differs only by a nonzero angular momentum.

There is an Oppenheimer Snyder metric that is an 'unrealistically simplified' solution to the formation of a black hole, but it fails to describe conditions at the singularity. I was hoping at least for some indication of the whole compression vs. tension distinction.

None of these metrics seem to include Hawking radiation, so they describe black holes that exist for infinite coordinate time.

Rennie continues:

"[Observers falling with the star collapse] see the singularity form in a finite (short!) time, but ... the Oppenheimer-Snyder metric becomes singular at the singularity, and that means it cannot describe what happens there. So we cannot tell what happens to the matter at the centre of the black hole. This isn't just because the OS metric is a simplified model, we expect that even the most sophisticated description of a collapse will have the same problem. The whole point of a singularity is that our equations become singular there and cannot describe what happens.

All this means that there is no answer to your question, but hopefully I've given you a better idea of the physics involved. In particular matter doesn't mysteriously cease to exist in some magical way as a black hole forms."

So my post seems to be based on information about static metrics (Schwarzschild, Kerr, others), the geometry of which shows an end to time and no matter at all, but neither do those metrics show the end to the matter that made them since these kinds of black holes are not 'made'. They exist for eternity. So Op-Sny is probably a better metric despite being 'unrealistically simplified'.

A coordinate system that isn't singular at the event horizon (like Kruskal–Szekeres coordinates) shows worldlines of infalling particles just ending in time at the singularity, not persisting with the other matter persisting there. The worldline of compressed matter would not end, but only join all together with the worldlines of other particles.

As you (as an observer) fall into one, tidal forces pull you apart, not compress you. This doesn't stop at the EH. So compression ever happens, then the naive description would be when you smack into that physical singularity there where everything else has gathered. None of the metrics describe that. At best they just don't answer the question at all, and on those grounds, I am reneging on the authoritarian tone of my prior replies without suggesting that the 'high density matter' description is a better description.

Learned stuff today, which makes this a win topic. I hope we all have.

32 minutes ago, MigL said:

Calculations suggest a Black Hole ( Schwarzschild ) to be a net emitter of radiation at the current CMB temperature, it would be about the mass of the moon.

Yes, I've seen places that compute that mass. A moon mass is still going to take an awfully long time to radiate away at CMB temperatures. Infinite time actually, at least until the CMB radiation stops adding mass as fast as HR bleeds it off.

On 5/2/2024 at 7:36 AM, Genady said:

A few grams?

Yes. A black hole near end of life has almost no mass remaining.

15 hours ago, MSC said:

I thought gravitons were hypothetical and that gravity doesn't need a particle to carry force as it's an effect of mass on space-time.

Gravitons as in gravitational waves, not any sort of force carrier. Gravitational waves carry information about changes to spacetime geometry, and an evaporating black hole is such a thing, so it has to generate such waves, whether or not those waves can be broken down into quanta.

15 hours ago, MSC said:

Also how does the vast majority of mass radiate away if only massless particles are formed just before the event horizon?

Light is energy. Any radiation reduces the mass of the thing radiating it. Light also has momentum.

15 hours ago, MSC said:

Is Hawking radiation not made up of any particles with mass? 

For small black holes, sure, but for larger ones, the odds of something like a positron escaping is incredibly low. Most would fall right back in due to gravity. Gravity can't pull back light if it's going in the correct direction (straight up).

15 hours ago, MSC said:

Also I just don't see how an object or class of objects that vary greatly in size and mass, the mass of which is reducing slowly over time, will be able to keep a strong enough gravitational pull to keep all the matter crushed down below it's Schwarzchild radius if the reaction at the core is so energetic, why wouldn't it be able to break free of the blackholes gravity once it ceases to be one?

There's no matter in a black hole. A Schwarzchild black hole is a vacuum solution. Nothing gets squished in there. Things falling in actually get pulled apart.

The singularity is not a location in space where there is matter squished together unreasonably. It's a line/plane/fuzzy region where time just ends.

14 hours ago, Mordred said:

The singularity or as  close to singularity as possible ie near infinite density would still have sufficient gravity as well as other related forces to maintain an EH even if that EH is smaller than a soccer ball etc. 

This comment suggests dense material in there somewhere. This is a misconception.

12 hours ago, MSC said:

I'm still confused as to where the mass goes as a blackhole evaporates. Is it better to think of it as losing energy? 

Yes, better. Energy & mass are equivalent. The mass doesn't exit the black hole, but is created outside by separation of virtual particles, with the one with negative energy falling in and adding that much negative energy to the BH. The vast majority of the time, both virtual particles are thus pulled in, netting zero energy to the BH. The odds of one escaping becomes larger with the small holes.

8 hours ago, MigL said:

When the remaining mass is no longer able to support an Event Horizon, and it can be quite a large mass,

I don't know where the limit is, and what it means for mass to not be able to support an EH. I think a unified theory would really help give real answers to this. My statement of 'a few grams' might be way off, but classically there is no minimum mass, and at sufficiently low mass, the radiation becomes significant enough to qualify as an explosion. There is still nothing actually from inside the black hole escaping. There is no matter in there.

On 4/28/2024 at 10:37 AM, MSC said:

If an evaporating black hole will eventually lose it's event horizon and explode as MigL said; would that lead to the potential for more star formation

The end might produce a few grams of actual matter in a brief burst of radiation. "Explode" makes it sound bigger than a wink.

The vast majority of the original mass radiates away as massless particles, mostly photons and gravitons, neither of which is a building material for stars.

On 4/29/2024 at 10:31 AM, DanMP said:

Now, at the opposite side of the Earth (from the tower), the travelling twin turns the telescope from backwards to forwards, and by this action he is changing his perception from moving away to moving towards the tower twin. In this case there is no acceleration (change in velocity), no actual turning back, but the difference in ageing would be the same as he turns back with instant change in velocity and direction, like in a relay version.

To me, this is yet another indication that:

On 4/26/2024 at 9:00 AM, DanMP said:

only the speed of the travelling twin is the cause

 for the differential aging in the twins' paradox, not the acceleration, nor the frame change.

Yes, when the orbiting twin turns his gaze around, he will appear to be approaching instead of receding. So the redshifted view of the tower clock will change to blue shift, the difference being purely Doppler effect in both directions.

The dilation is due to speed, and speed isn't affected by where anybody is looking, so the dilation is unchanged at the far side of the planet.

Yes, there is acceleration, but all of it orthogonal to motion, so since the 'twins' are at the same potential, the dilation is constant for the entire orbit.

It is objective. The orbiting twin will be younger when the meet again, just like the one that goes out and back to the distant star.

To do this in special relativity, the planet can have no mass, and the 'orbiting' twin would need to curve his path via say a string tied to the center of Earth to get him to curve is path like that. Rockets also works, but the engineer in me hates to waste fuel when there's a better way.

12 hours ago, Moontanman said:

Thank you, exactly what I was wondering but I didn't realize the station was necessary. 

The station isn't necessary.  All that is needed is a frame reference. One can say that each rocket is moving at .9999c relative to frame arbitrary abstract inertial frame S which happens to have nothing stationary in it.  The lack of a stationary object in S would make it difficult for any rocket guy to directly measure that speed, but it can still be computed. A frame is, after all, an abstraction, not a physical thing.

So if X is moving west relative to S at 0.9999c and Y is moving east relative to S at 0.9999c, then X is moving at about 0.999999995c relative to Y and V-V.

(.9999 + .9999)/(1 + 0.9999*0.9999) = 0.999999995

12 hours ago, Moontanman said:

The observer is on each rocket, the rocket judges its own speed by its departure point

In that case the velocity of the two respective departure points relative to each other needs to be specified. Without that, there is no way to compare the rocket speeds relative to each other since there can be no common frame.

Usually, in the absence of an explicitly specified frame, an observer on any object (a rocket say  judges his own speed to be zero.

52 minutes ago, md65536 said:

You're referring to "celerity", which is different.

So it seems. Imagine how many posts I've made that are then wrong. My definition of proper velocity seems right, but that's different than rapidity.

I must admit I need to digest that page better to figure out what the rapidity actually is, how it is useful.

On 4/19/2024 at 5:15 AM, md65536 said:

How can a measure of velocity be called an acceleration? How is a measure of velocity a type of Lorentz transformation?

Is there some sensible meaning to what I quoted that I'm just not comprehending?

The way I've heard 'rapidity' used is as a proper velocity.  It is proper acceleration integrated over proper time, and thus it adds the normal way.

Two obvious examples:

I accelerate my ship away at 1g in the same direction for 3 years ship time. That gets me up to a rapidity of a bit over 3c, meaning I travel 3 light years (Earth inertial frame) for every year I age. At that rapidity, the ship has a velocity relative to Earth's inertial frame of about 0.995c

Second example is recession rates of galaxies.  Gnz-11 (no longer the most distant object seen) is increasing its distance from us at a rate of about 2.3c.  That's a rapidity.   Rapidities add the normal way. If galaxy X recedes from us at 1.2c and galaxy Y (further away from us on the same line) recedes from X at 1.3c, then Y recedes from us at 2.5c.  If an inertial frame was valid over such distances (such as it would be in say a zero energy Milne metric), then that rapidity of GNz-11 would correspond to a velocity of 0.98c.  This underscores the fact that recession rates are not expressed relative to any inertial frame.

Anyway, since the usage comes from Mordred, he may be using the term in a different way than I tend to see it.

On 4/14/2024 at 3:59 PM, scherz0 said:

By disregarding [1,31], you flout the lottery’s random distribution of winning integers!

Non-sequitur. All numbers have equal chance of winning, so no choice, popular or not, alters your odds, but as swansont points out, unpopular numbers yield better average payouts.

On 4/14/2024 at 3:59 PM, scherz0 said:

As [1,N] contains more integers than [32,N], picking numbers ∈ [1,N] proffers more chances to win than picking ∈ [32,N]. Q.E.D.

You seem to presume N is less than 64, which is not always the case. Even if it is the case, your conclusion is again a non-sequitur. Picking five random numbers under 32 gives the exact same odds of winning as picking 5 random numbers in the range of say 33 to 40. This is the simplest of mathematics: Every possible choice has the same odds as any other if the draw is random.

21 hours ago, Airbrush said:

Launch a rocket towards the asteroid, and at the correct moment the rocket turns around and decelerates to zero, then accelerates the opposite direction to match the velocity of the asteroid.  Then the rocket launches 4 separate rockets, each pulling the corner of a giant, square, cable net.  The rockets decelerate the asteroid enough, so it won't hit earth.

Decelerating the rocket just wastes all the momentum it already had. If you have delta-V left over, accelerate more, not decelerate. This gives maximum momentum transfer to the thing, which is what is needed to deflect it. Of course, it's best to hit it more or less from the side, which is inefficent for something coming more or less straight at you.

9 hours ago, MigL said:

the farther away you can influence the asteroid's trajectory, the less force is needed to produce sufficient deflection

Indeed, but also the harder it is to tell if the effort is needed at all, or if the effort will actually make the trajectory worse, due to miscalculation.

Look at all the news about some asteroid that's going to hit Earth, and then it misses it by a mere million km. You can't send a defection mission out to every big rock that might get that close, but by the time we know it will hit, it's too close that a small defection is enough.

It's also harder to get something out to an incoming object quickly if its further away. Takes more delta-V to get out there, leaving less to actually impart momentum to the thing.

I don't think nukes are very effective in a vacuum. It will leave a nasty stain and small crater and will defect almost not at all, unless you can get the thing to embed itself a ways in without destroying the mechanism in the process. There is armor-piercing technology that helps with that sort of thing. Look at the bunker-buster bombs they have, designed to penetrate a long way and still explode, sometimes even hours later. But those bombs are heavy and not too fast, hitting at far slower speeds than what would likely occur in a rocket/asteroid interception.

On 4/7/2024 at 8:07 PM, geordief said:

Could we calculate spacetime intervals at every stop on the way,add them all up and end up with a figure that was comparable to the first spacetime interval when we just used the two events?

Yes, they'd be comparable. You're asking if a straight line (or a geodesic one) is a similar length to one with some minor curvature to it, and both are about 2000 years long, differing only in perhaps the 6th significant digit (a guess).

The length of the actual worldline would be a tiny bit shorter than the interval between the two events. This is essentially the gist of the twins scenario where one twin has a shorter worldline than the one with the straighter worldline.

23 hours ago, grayson said:

I once heard a paradox where a finite universe loops on itself when you go near the speed of light due to length contraction.

PBS space time is a pop science source. They can say what they want.

Speed for one is relative, so for instance I am currently going very near light speed relative to a muon waiting for me to go by it. The universe is unaffected by my moving at this speed. The speed at which something goes relative to something else has zero effect on the geometry of the universe. 

23 hours ago, grayson said:

I heard from this video from kurzgesagt, that one possible model of the universe was a doughnut.

It is possible, but a 3D torrid surface, sort of like the video game asteroids takes place in a 2D torrid surface. It means that there are preferred axis orientations, and that if you travel along any of these axes, you get back where you started. Any other direction and you don't. Your post seems to describe something like that.

Such a universe would be unbouned, but finite in volume, very much like the surface of Earth, except retaining the flat curvature.

23 hours ago, grayson said:

My thought is what if you went at such a percentage of the speed of light, that the short loop of the doughnut loops around. 

The universe is much larger than the distance to the event horizon, and since one cannot reach the event horizon, one cannot traverse even one loop no matter the speed.

Presuming that expansion wasn't accelerating (or happening at all, for simplicity), there would be no event horizon, and thus one could go all the way around. So in asteroids, the universe isn't expanding at all, and if one goes vertical, you get back to the staring point after 1 lap, in say 5 seconds. If you go diagonal at the same speed, it might take a minute to get back approximately to the center of the screen, the starting point.

23 hours ago, grayson said:

Now, what would the other person see that goes around the long loop of the doughnut going at the same speed. One of the people would experience a little bit of length contraction

You seem to presume that one direction is longer than another, sort of like the asteroids screen not being square. That's fine, but it isn't necessarily the case.  If two depart from the center at the same speed and time, the vertical guy gets back before the one going the long way. If the aspect ratio is 3:4, then it will take 3 or 4 laps for them to meet each other again.

Length contraction plays no role in this. For one, it is a coordinate effect, not strictly a physical one. A length contracted ship going at 0.9c still gets 3.6 light years from here in 4 years (as measured by 'here', the frame in which he is contracted).

23 hours ago, grayson said:

One of the people would experience a little bit of length contraction

It being a coordinate effect, one does not experience length contraction. One is by definition always stationary relative to ones self, and thus there is no contraction to experience.

And a paradox isn't something experienced either. You've not identified any paradox. You just say that there is one.

What each person would see, if moving fast relative to stars, is a bunch of stars moving fast relative to him. They both see that. There is no paradox identified.

I can think of at least three kinds of time, and the distinctions are important.

On 1/7/2024 at 3:39 PM, swansont said:

One definition is that time is what is measured by a clock.

What clocks measure is proper time, which, in GR terminology, is the spacetime interval along the time-like worldline followed by the clock, completely analogous to proper distance being measured by tape measure following a space-like worldline.

Proper time is an invariant (it is not frame dependent). It is physical and very real.

On 1/7/2024 at 1:31 PM, chron44 said:

I assume the halved "time" concept, for example, in the well established spacetime (GR/ SR) concept, is a physics issue.

If we only discuss "time" used in science: What is time in physics?

.. If persisting in my view of time being a physical issue, and not only a metaphysical subject.

Getting beyond strictly physical, there is also coordinate time. Coordinate time is the time coordinate assigned to events by a particular abstract coordinate system. It is purely abstract (a mental thing, not a physical one). It is very frame dependent, but still physics, not metaphysics.

If we get truly down to metaphysics/philosophy, we get to the third kind of time, which is the progression of the present moment. It is 'that which flows'. When somebody asks if time is real, they're probably talking about this kind. It probably has an official name but I don't know it.  I call it teapot time since like the teapot purported to be in orbit around the sun somewhere beyond Jupiter, there is zero empirical evidence for it, but its existence also cannot be disproven.

So to give an example of the three kinds, we decide to throw Bob (and his watch) into a black hole.  In some coordinate systems (say that of a distant observer), Bob takes forever to reach the event horizon. In a different coordinate system such as Kruskal–Szekeres coordinates, he falls right in in some finite time X. That's all coordinate time.

Proper time is easy: Bob's watch reads time P upon reaching the event horizon. That value is the same regardless of choice of frame.

As for proponents of teapot time, the only theory I know that includes it is forced to deny the existence of black holes at all since events within cannot exist, so any talk about falling into one is unsupported. This of course provides a semi-empirical test for presentism. If you jump into a large (at least say 15000 solar masses) black hole and find yourself inside, you've disproved presentism, but of course you cannot publish your findings in a science journal any more than you can publish your discovery of an afterlife. One has to die to test it, and the guy inside the black hole is, while not yet dead, certainly doomed.

On 10/24/2023 at 3:07 PM, giorgi_lamp23 said:

Now the question is: knowing n what is the most probably value s will have? which means what’s the number of pen marks he’s most likely to give?"

As I said before we could re range this problem in something very practical such as: "Listening to a playlist of n songs with random playback, how many songs will I most likely have to listen to to make sure I listened to all the songs on the playlist?" or, for example, you could make an analogy with a bag of marbles or a deck of cards.

You're asking two different questions:

What is the most likely value of s when all of the list has been selected at least once?

At which value of s will it be more likely than not that all of the list has been selected?

The answer to the first question is seems necessarily lower than the answer to the second. Do you see why? I don't see an obvious way to derive either value right away.

It's a top, simple as that. Not clockwork at all.

We had these as kids. They went under the brand name 'whizzers' or some such. This one is decorated as a bug.

The wheels underneath drive an internal vertical-axis flywheel.

You'd get quicker responses to your questions if the title actually gave any clue as to what the topic is about. You seem to give the same title to all your topics, however unrelated.

15 minutes ago, Bufofrog said:

Maybe Yahweh just started the universe last Wednesday programed all our past memories and the future is all set in stone.

You got it all wrong Bufofrog. What kind of fool is going to believe that?

Everybody knows it was last Tuesday, not Wednesday.

8 hours ago, Mgellis said:

Is it simply a matter that people could produce enough thrust with the wings to lift themselves into the air once they reached a certain low weight? 

People can produce enough thrust to fly here on Earth, but it takes an athlete. Don't know the current record, but somebody flew over the English channel with human-powered flight. So sure, if you can do it at 1g, you can do it at lower g with less effort.

I think your mistake is presuming it is just a matter of strapping on winds and arm-flapping. But our arms are situated nowhere near our center of gravity, so instead of flying horizontally like the pictures depict, you'd hang vertically if all your weight was born by your arms.  I suppose it could work, but the aerodynamics would be horrible. All gliding done by humans is a different setup designed to support you everywhere, hence the funny flying-squirrel setup that the base jumpers use.  I suppose that one could generate thrust by a more 'flappable' version of one of those.

8 hours ago, Mgellis said:

I suspect mechanical wings, with their own motors,

That (gasoline, electric, etc) would be powered flight. We also have that here on Earth, so again, doing it at low g would be easier.

You can also strap on a rocket, something else a human can do here on Earth.

What if the pressure was much higher?  How much easier/harder would it be to fly at say 1g or less with thicker air. It has more mass to support you, but more drag as well. If it's dense enough, the buoyancy alone would be enough.

1 hour ago, grayson said:

It is explaining that V₁, or the velocity of the universe

The velocity of the universe would be the change in its position relative to something that isn't the universe. It really makes no sense for a universe to have a velocity.=

1 hour ago, grayson said:

or the last velocity of the universe per second per megaparsec

Velocity per second per megaparsec would be something like v/t/d (velocity, time, distance) which is d/t / t / d which is 1/t², something with different units than velocity at least.

As for special relativity, that only applies to flat Minkowskian spacetime with zero energy and mass anywhere. For this reason, it is simply inapplicable to our universe except locally.

Your equation adds values of different units, which makes it meaningless. You can't add meters to Pascals, and (in your case), you can't add H (units 1/t) to V/γ (units d/t)

Another criticism: γ is the Lorentz factor of what exactly?  It should be the factor for some speed, but "the Lorentz factor which is used in incorporating special relativity into the equation and using the laws of special relativity" is just a word salad.

12 hours ago, TheVat said:

It's aspect dualism, if you peek under the hood.

Aspect dualism is effectively a violation of known physics. Such a violation would be required for any agency that is not tethered to physical causality. A non-deterministic interpretation of quantum mechanics does not open the door for this sort of thing since willed agency cannot emerge from the probabilistic description of quantum theory.

One that claims such a relationship would need to demonstrate some structure in the privileged arrangement of matter (probably just humans) where a signal is generated purposefully (not randomly) without cause. There's no structure in a person that is seemingly designed to do anything like that.  All structures at any scale seem to be evolved for repeatable (deterministic) operation, just as are transistors.

12 hours ago, TheVat said:

For some, it's a way to distance oneself from the clockwork universe.   

I'm sure. Humans are excellent at rationalizing what they want to be true. Most are not so great at actual rational thought.

Hence all the 'proofs' that not only does God exist, but a proof of exactly my version of God.  All those proofs (but one at most) must be wrong, and even that statement doesn't pass rational analysis.

12 hours ago, TheVat said:

So there could exist worlds where counterfactuals were the reality

This doesn't seem to make sense. It seems to suggest that MWI supports the existence of worlds where MWI is wrong, since MWI does not hold to PCD.

12 hours ago, TheVat said:

where Alice, regretting that she didn't call Bob, did in some world call Bob, with positive consequences.  Each world would still be deterministic from a physicalist perspective, but all counterfactuals would be permitted in a larger view of all possible Alices, with all possible evolutions of the state vector.

None of those seem to be examples of counterfactuals. They're all states measured by Bob and/or Alice.  The (one) universe as a whole is deterministic under MWI. I don't think the concept of a given world being deterministic is accurate there. It cannot be since any given world is the result of random events.

Yes, Alice & Bob hook up in some worlds and not in others. In other worlds, one or both don't even exist. But as a whole, all those states exist in superposition. I don't think that qualifies as a counterfactual of any kind. Saying the cat is dead is a counterfactual. Saying the cat is in superposition of dead and alive is not.

49 minutes ago, studiot said:

Or they will never complete a game.

Then the robot should predict the indecision and play anything (the game does have a time limit you know), instead of losing by default. You've just pretty much proved Godel's theorem about the halting problem.

52 minutes ago, studiot said:

This asked whether determinism refers to a single event (eg your robots playing RPS) or goes back some indeterminate distance down a causal chain of events.

It cannot do down either a single path or a finite distance. Events (such as my choice of footwear today) depend on many causes (the weather being but one), and those causes themselves have to have come about due to other states even prior. That 'chain' spreads both in width and depth all the way back to the big bang.  This is true under determinism or not. The difference is that under nondeterminism, some of those causal branches stop. A choice I make might be partially a function of a beta decay somewhere. That particular piece of state (among the myriad of states that contributed to my choice) was uncaused, a true random occurrence under nondeterministic interpretations.

The robots playing RPS is not a single event. I suppose their eventual choice is, but there's a lot of state that potentially contributes to its eventual choice (or lack of it).  If the robots are identically constructed, then it would be like you trying to win RPS with your own reflection.

I don't understand how any of that aids in the question of 'what definition of determinism is in play'. The definition is something along the lines of the complete lack of randomness: That identical closed systems in a given state will evolve the exact same way every time. Was there another definition that is fundamentally different than that?

1 hour ago, studiot said:

FYI my mathematical comment observes the fact that a chain of probabilities (eg a chain of event each with a probability) does not in general converge to zero but to a definite value and is therefore deterministic, even though we do not know the individual probabilities involved.

Only some systems exhibit this. You drop successive grains of sand from a fixed point and which way a given grain goes is fairly unpredictable, but the eventual conical hill of sand is very predictable.  Most systems are chaotic, under which small perturbations result in macroscopic differences. The weather, the formation of galaxies from a uniform early state, are examples of this.  Take the state of Earth just after the Theia event. From that state, life is unlikely to form, and if abiogenesis does occur, it will most improbably evolve into anything that would be recognized as a mammal.

9 minutes ago, martillo said:

Seems it is not the case you mention.

It indeed seems not the case.  The stanford page on libertarianism doesn't even mention determinism at all. I stand corrected on that point.

There's the compatibilist view I suppose, but it requires a sort of soft determinism. Now I really wonder why 'free will' is a desirable thing.

3 hours ago, martillo said:

I'm the only one here defending the "libertarian" current of philosophy on the subject in which "free will" and "determinism" cannot coexist at the same time.

I do believe the libertarians assert both free will and determinism, that the one is possible despite the other. Your stance, at last what I can make of it, doesn't look like that.

I for one would I suppose qualify as libertarian, but only because I define free will in such a way that is 1) completely compatible with determinism, and 2) actually something that is desirable. A more typical definition of free will seems like something I'd not wish to have, and it is indeed often incompatible with determinism.

1 hour ago, studiot said:

Well why not show it then ?

Build two machines that play rock paper scissors. They are constructed so that each uses a completely deterministic in algorithm, and each has full access to the state and programming of the other.  If the behavior can be predicted because it is deterministic, then each robot can predict the move of the other and always win. Since the machines can't both win, predictability cannot be had despite the deterministic nature of the situation.

Godel did a simpler proof, but that one is a bit more on topic.

1 hour ago, studiot said:

Re this second quote and 'predictability v determinism'.

The mathematics of continued products would disagree with you.

I don't understand these comments or the relevancy to my comments to which they replied. Perhaps you don't grok what I said. I admit the lack of elegance in my conveying it.

37 minutes ago, sethoflagos said:

By being explicitly non-local, Cramer's Transactional Interpretation is immune to Bell's inequality test while being entirely consistent with counterfactual definiteness.

I think any non-local interpretation can be (but not necessarily is) consistent with counterfactual definiteness.

Does determinism depend on counterfactuals?  MWI for instance is considered fully deterministic but denies counterfactuals, but I'm not sure how a wave function can be properly expressed in the absence of counterfactuals. I lack the expertise to resolve that.

You also mention a block universe, but I don't think a block universe necessarily implies determinism, so I don't see the relevance between one interpretation of time or another.

On 11/7/2023 at 7:59 AM, Eise said:

For the record, I do not say the world is determined: QM shows it isn't.

QM shows that it isn't predictable, but until the fully deterministic interpretations are falsified, QM does not kill determinism.

On 11/7/2023 at 8:02 AM, studiot said:

There is a cause and effect connection to determinism so if we can consider the very last cause before the effect Joigus comment of how far back can we go along the chain of cause and effect is pertinent.

If you can go back even a short time, then that prior state must be fully determined by the state shortly prior to that, and so on...

Hence if we can go back a little and retain determinism, then we can go back all the way to the beginning.  Of course there's no evidence of this short term determinism. For one, it presumes a meaningful state of a system, which is a counterfactual, and few interpretations of QM support counterfactuals.

On 11/7/2023 at 8:02 AM, studiot said:

When I said that humanity has never known enough to determine everything

Don't confuse determinism with predictability. One can have a nice classical fully determined universe (such a Newton might have envisioned) and it would still not be predictable. It's pretty easy to show that.

On 11/7/2023 at 9:21 AM, sethoflagos said:

Given a free neutron in whatever initial boundary conditions you care to set, in what sense could its instant of decay into a proton and W^- be understood to be '(pre)determined' prior to the actual event?

That's a good example of an uncaused thing. Bohmian mechanics (which supports counterfactuals) would I think assign hidden variables to the neutron system and a thousand identically set up systems would all decay after the same duration.  MWI (also deterministic) would say that it decays after every possible duration. Copenhagen simply says we cannot know. Most of the others say something on the order of it occurring at some random time, which in some cases is 'God rolling dice'. None of the modern deterministic interpretations were out there during Einstein's time, and he seemed like a determinist type to me, so that's too bad.

There are people (at least one of whom is contributing to this topic) which seem to spin a deterministic universe in a bad light, like it is somehow a thing to be avoided if possible, especially for decision making. I don't understand this aversion. I cannot conceive how a better decision can be made through a non-deterministic mechanism than through a deterministic one. All of evolution has favored structures that generate consistent output from identical inputs, despite leveraging quantum process in doing so. This shows that determinism is a good thing, even if it doesn't exist in reality.

On 11/2/2023 at 5:37 PM, Chris Sawatsky said:

How can scientists detect stars that are more than 13.7 Billion light years away?

Light from that star was emitted about 8 billion years ago when the star was about 5.5 billion light years away, both time and proper distance per the cosmic (expanding) coordinate system.  That star, if it currently exists (unlikely), is a burnt out husk right now and doesn't shine at all. More likely it blew up and doesn't exist at all, or is a black hole or some such.

On 11/2/2023 at 5:37 PM, Chris Sawatsky said:

If the Universe is 13.7 Billion years old, light could not be travelling for more than 13.7 Billion Years

Yes, it could not have been traveling for longer than that, and it doesn't need to. Such distances use an expanding coordinate system where light speed isn't constant.  But also, absolutely nothing we see in the sky now was emitted further away than about 6 billion light years away (proper distance). Sure, the galaxy/quasar/whatever may be 40 billion light years away now, but we're seeing it where it was long long ago, which was much closer. The CMB light is the oldest, and that light was emitted from less than one billion light years away. That light isn't from any 'star', but it is from the formation of the first hydrogen atoms.

On 11/2/2023 at 5:37 PM, Chris Sawatsky said:

In my way of thinking, everything began expanding out from a central point

You're going to have to unlearn this common misconception if you want to actually understand cosmology. The big bang happened literally everywhere and was never a 'point', and there is no rushing of material from a point into 'empty space' so to speak.

On 11/2/2023 at 5:37 PM, Chris Sawatsky said:

I watched a doc that stated various boundaries that have been discovered. They were said to be Hundreds of Billions of Light Years away.

Getting your information from peer-reviewed sources is a far better choice. I can find a 'doc' that states just about any nonsense I wish. Your source apparently claims to have measured something outside the observable universe, something which is by definition a contradiction.