Three different FE’s, three different butchered versions of gravity.

One reason is because it lacks a justification for the directionality, which violates one of the fundamental assumptions of science without which there would be a massive question of if science could be done at all. And that is the assumption of isotropy, that all directions should be the same.

I agree it violates the assumption, but that doesn't seem to imply impossibility - by its nature, an axiom is an unproven thing. The question of if science could be done at all, eh, I think it could, it'd just be trickier. The worst thing would be getting a note of 'Assuming simpler conditions' or some such in basic equations that assume isotropy.
Plus, if as I assume you're talking the cosmological principle, that's something that has been criticised even among mainstream scientists, and some do question whether it matches our observations. I don't think it's a solid bedrock necessarily, even outside of FET.

It provides no justification for the rate, especially given the rate varies across Earth.
...
The big issue with this idea is that it means so many of the FEer excuses for why gravity can't be right would also apply equally to this.

The rate varying would presumably come down to variations in air density, which, ooh, that could be fun to puzzle out. Slightly less air at poles, slightly denser at the equator, etc - for me, the question is if the thinner air at the tops of mountains would see things fall faster, while RET would expect the opposite. Maybe we run into too narrow an error margin, but that could be a fun avenue.
I agree that there are questions to ask, etc, and that a few-line summary of a density model don't provide a fully detailed replacement for a mathematical model in every possible situation, though assuming impossibility in that situation doesn't feel helpful to me. Either way, I was just interested in your specific objections to taking the significance of the down direction alongside 'objects sort themselves out by density.' If, for the purposes of a hypothetical, we grant a sufficient model of the world assuming that, and that the justification is to take it as law akin to 'mass bends spacetime' of just a description of what happens, if your main objection would be the isotropy concern?

Which means if you had a vacuum, then things should just float, but even in situations where the tiny amounts of air inside a chamber can't be modelled as a bulk gas and instead acts as individual particles primarily bouncing off the walls of the chamber, things still fall.

That one I agree is an interetsing one. If it is dependent upon air as opposed to a general property, then I agree there are more major issues.

And to throw in one more, you have this claim here:

Quote from: bulmabriefs144 on November 30, 2022, 05:43:14 AM

The point being, while that shelf was around, it comfortably held three extra books, and a few chotskes beside, with no "constant downward force". The shelf acts as a limit to the books, until entropy final breaks it down (but this means for years and years the shelf works fine so long as it cleaned and cared for). But if it is suddenly gone, the books compare themself to the air, and the air loses.

Which appears to be claiming that if you place on object on another object that is more dense than it, it would experience any downwards force.
So for example, if you were to place down a jug of water on a scale, and then add something less dense than the water on top of it, then there should be no additional downwards force and the scale should read the same.

I don't agree with that characterisation. Density isn't a local property - if you zoom into the smallest scale, an atom has no notion of density. It's a property that only arises when you zoom out and account for the surroundings. It seems like the only coherent way to take this model, long before you get to that experiment, is as a property of overall density - the density of a whole system, buoyant objects and jug alike, would define the force exerted on the system. There might be no force on the ball, but the ball and jug as a unit would still possess different density to just the jug, etc.
Like, if you take an object that isn't uniformly dense, presumably there's a centre of density akin to the centre of mass we use to model gravity.

The 'no downwards force an an object at rest on a surface' I agree seems problematic, but I will admit to being unconvinced this argument works against it.

I agree it violates the assumption, but that doesn't seem to imply impossibility - by its nature, an axiom is an unproven thing. The question of if science could be done at all, eh, I think it could, it'd just be trickier. The worst thing would be getting a note of 'Assuming simpler conditions' or some such in basic equations that assume isotropy.
Plus, if as I assume you're talking the cosmological principle, that's something that has been criticised even among mainstream scientists, and some do question whether it matches our observations. I don't think it's a solid bedrock necessarily, even outside of FET.

It is correct that it doesn't imply impossibility. But it does give serious cause to question it. Especially when there is an alternative that doesn't require anisotropy.

The rate varying would presumably come down to variations in air density

Except it can't, as we can measure the air density.
And high precision devices typically use a vacuum, so the air is no longer a factor.
And it isn't down to the gravimeters as that would make it vary depending on which one you use.

And there is also the issue of symmetry or lack thereof.

With gravity the buoyant force is directly proportional to the strength of gravity.
That means that at the equator, with a lower strength of gravity, not only would a lead ball feel less force pulling it down, the upwards force on a balloon will also be reduced.
But if it was variations in the density of the air, the lead ball should feel less while the balloon feels a greater upwards force.
However doing the test in a repeatable way with helium leaking out may be problematic, and it would require a rigid balloon.

Either way, I was just interested in your specific objections to taking the significance of the down direction alongside 'objects sort themselves out by density.' If, for the purposes of a hypothetical, we grant a sufficient model of the world assuming that, and that the justification is to take it as law akin to 'mass bends spacetime' of just a description of what happens, if your main objection would be the isotropy concern?

I wouldn't say it is one main objection. I think a few objections are of equal importance.
The main objections are the anisotropy, variations in rate, and the pressure gradient and implications thereof.

If instead of taking objects sort themselves out by density we instead take for granted a law that objects experience a downwards force proportional to their mass and some unknown factor, then the main objection is the anisotropy, with a big question of what is this unknown factor?

I don't agree with that characterisation. Density isn't a local property - if you zoom into the smallest scale, an atom has no notion of density. It's a property that only arises when you zoom out and account for the surroundings. It seems like the only coherent way to take this model, long before you get to that experiment, is as a property of overall density - the density of a whole system, buoyant objects and jug alike, would define the force exerted on the system. There might be no force on the ball, but the ball and jug as a unit would still possess different density to just the jug, etc.
Like, if you take an object that isn't uniformly dense, presumably there's a centre of density akin to the centre of mass we use to model gravity.

The 'no downwards force an an object at rest on a surface' I agree seems problematic, but I will admit to being unconvinced this argument works against it.

My understanding of that description is that there is no downwards force on a surface by an object less dense than it.
If that is the case, then in the foam ball example, there is no downwards force acting on the water so there should be no force to transfer onto the scale.
But as they are saying there is no downwards force acting to make the object move in the first place, it is unclear exactly what the implications should be, and the real question is why is there any reading on the scale.

Also, I would say an individual atom does have a density, as it has a volume and a mass, but that this is greater than the density of the system it is in due to the voids in the structure.

Quote from: Slime on December 10, 2022, 01:09:44 PM

I agree it violates the assumption, but that doesn't seem to imply impossibility - by its nature, an axiom is an unproven thing. The question of if science could be done at all, eh, I think it could, it'd just be trickier. The worst thing would be getting a note of 'Assuming simpler conditions' or some such in basic equations that assume isotropy.
Plus, if as I assume you're talking the cosmological principle, that's something that has been criticised even among mainstream scientists, and some do question whether it matches our observations. I don't think it's a solid bedrock necessarily, even outside of FET.

It is correct that it doesn't imply impossibility. But it does give serious cause to question it. Especially when there is an alternative that doesn't require anisotropy.

Can we agree to disagree on that? To me, isotropy is an assumption, and necessarily not one backed up by evidence. It's not a fundamental assumption without which there is no reason or science, dropping it seems possible, and is considered even within the current possibilities. To me, it isn't something that seems like it comes with any weight beyond convenience.

I wouldn't say it is one main objection. I think a few objections are of equal importance.
The main objections are the anisotropy, variations in rate, and the pressure gradient and implications thereof.

I think we can agree that there are other things there that do need to be explained. Vacuum tests, and justifying variations with respect to altitude and location - like, the basic fact of if we can run experiments to see objects being sorted by density will always be present.
Like, you know my stance - I wouldn't consider them of equal importance, the isotropy assumption wouldn't hold a candle to testable contradictions in my mind, but I would agree with those other concerns.

My understanding of that description is that there is no downwards force on a surface by an object less dense than it.
If that is the case, then in the foam ball example, there is no downwards force acting on the water so there should be no force to transfer onto the scale.
But as they are saying there is no downwards force acting to make the object move in the first place, it is unclear exactly what the implications should be, and the real question is why is there any reading on the scale.

Also, I would say an individual atom does have a density, as it has a volume and a mass, but that this is greater than the density of the system it is in due to the voids in the structure.

I think that reasoning only holds if we're talking about gravity. In that case, force transference would absolutely be necessary. The contention though does seem to be that this isn't a force exerted by A on B any more than incidentally.
There is admittedly a chance I've got my wires crossed and am thinking in terms of denpressure, where the overall displacement would be the same for water and ball in contact even with no force. My thought process is that density, by definition, can be calculated for part of an object, for the whole object, and for a space beyond just an object. It would be non-uniform, but that's not an obstacle. If you have some magic way to keep an object glued to the air in a metre around it, that air would reduce the object's overall density. As that doesn't happen in reality, an object moves through the air, so the calculation is strictly theoretical,
In this case, the ball is present on the jug and water, and is stationary relative to it, so its density is part of the system. You can calculate mass and volume, and the numbers check out.
I don't think we can visualise this as simple kinetic energy where direct transfer is expected. If we treat this as a law that acts on density - which I know you have your issues with, but they're separate to this - then any increase in density will cause a system to fall faster. One could maybe better view this as a high density gas - you don't need molecules in a gas to physically collide in order to be higher density than surrounding air. So the ball on the jug, if we grant any reading on the scale, then this seems to justify an increased reading.
The object at rest exerting no force absolutely raises some concerns for me though, I do agree. I'm not able to justify that with my current understanding. I suppose one could argue that with a scale, it's not truly at rest - I know it's not how load cells work exactly, but the simplified notion of a compressed spring seems beneficial. An object placed on top of a spring will compress it, then when it exerts no force on the spring, the spring returns to its usual length - or tries to, and runs into the resistance of the object which against exerts a force in response, etc etc in a constant on/off. When compression is involved, I think one could justify tension.

...I feel like I put all of that terribly. Oh well, will see if I can do better tomorrow if I made a mess of it.

Can we agree to disagree on that? To me, isotropy is an assumption, and necessarily not one backed up by evidence. It's not a fundamental assumption without which there is no reason or science, dropping it seems possible, and is considered even within the current possibilities. To me, it isn't something that seems like it comes with any weight beyond convenience.

That mostly doesn't go against what I said.
I accept it doesn't imply impossibility.
But if we have 2 alternatives, one of which with an explanation for the directionality, without needing anisotropy of the universe, and the other which needs to invoke anisotropy without explanation; I would pick the one which explains the directionality.
It isn't just that this model doesn't explain the directionality and instead needs a fundamentally anisotropic universe; it is also that we have a model that doesn't require that.

As for the implications of anisotropy to broader science, it raises the question of how much any law will vary based upon directionality or location or time, and if this variation will vary over time and so on.
For example, if you conduct a series of experiments, and find results which didn't match predictions; was that because the underlying model was wrong, or because something has changed or a preferred direction has skewed the results?
Alternatively if you have a well tested model which works and you try to build something using that, will it actually work when built or will something have changed which makes it no longer work?

I think we can agree that there are other things there that do need to be explained. Vacuum tests, and justifying variations with respect to altitude and location - like, the basic fact of if we can run experiments to see objects being sorted by density will always be present.
Like, you know my stance - I wouldn't consider them of equal importance, the isotropy assumption wouldn't hold a candle to testable contradictions in my mind, but I would agree with those other concerns.

I would say that without the model being more fleshed out, it can be hard to say exactly what those contradictions are. e.g. are thing which are thought of as contradictions actually contradictions or just not understanding the model.
But you are probably right that some things, like the effect of the pressure gradient, are probably more important than the question of why down.

I think that reasoning only holds if we're talking about gravity. In that case, force transference would absolutely be necessary. The contention though does seem to be that this isn't a force exerted by A on B any more than incidentally.
There is admittedly a chance I've got my wires crossed and am thinking in terms of denpressure, where the overall displacement would be the same for water and ball in contact even with no force. My thought process is that density, by definition, can be calculated for part of an object, for the whole object, and for a space beyond just an object. It would be non-uniform, but that's not an obstacle. If you have some magic way to keep an object glued to the air in a metre around it, that air would reduce the object's overall density. As that doesn't happen in reality, an object moves through the air, so the calculation is strictly theoretical,
In this case, the ball is present on the jug and water, and is stationary relative to it, so its density is part of the system. You can calculate mass and volume, and the numbers check out.
I don't think we can visualise this as simple kinetic energy where direct transfer is expected. If we treat this as a law that acts on density - which I know you have your issues with, but they're separate to this - then any increase in density will cause a system to fall faster. One could maybe better view this as a high density gas - you don't need molecules in a gas to physically collide in order to be higher density than surrounding air. So the ball on the jug, if we grant any reading on the scale, then this seems to justify an increased reading.
The object at rest exerting no force absolutely raises some concerns for me though, I do agree. I'm not able to justify that with my current understanding. I suppose one could argue that with a scale, it's not truly at rest - I know it's not how load cells work exactly, but the simplified notion of a compressed spring seems beneficial. An object placed on top of a spring will compress it, then when it exerts no force on the spring, the spring returns to its usual length - or tries to, and runs into the resistance of the object which against exerts a force in response, etc etc in a constant on/off. When compression is involved, I think one could justify tension.

...I feel like I put all of that terribly. Oh well, will see if I can do better tomorrow if I made a mess of it.

I would say the reasoning holds regardless of what force is being discussed. Not only would it apply to gravity, it would also apply to electromagnetism, or even simpler things like pushing on things.
You have an object B applying a force to a measuring device.
You then introduce another object A, which makes contact with B, but which does not apply a force to B, yet somehow the force B applies to the measuring device increases.
The question is where is this force coming from?

But a much simpler route is to just find a set of objects, including a force sensor, such that you can place the lowest density object on top of the force sensor which is of a greater density, and place an even denser object below.
In such a cause the force sensor should read nothing if that claim is true.

But as they claim it isn't a downwards force making it move, I would say it is probably better to wait for them to clarify or explain more, rather than us going back and forth on it.

(I'm not sure what you are trying to say regarding the gas. Most gas collides a lot).

But if we have 2 alternatives, one of which with an explanation for the directionality, without needing anisotropy of the universe, and the other which needs to invoke anisotropy without explanation; I would pick the one which explains the directionality.
It isn't just that this model doesn't explain the directionality and instead needs a fundamentally anisotropic universe; it is also that we have a model that doesn't require that.

I think that's more a matter of taste than anything. You always run into those "What's more likely, A or B?" situations, especially in speculative stuff, and a lot of the time it's not based on anything concrete. If isotropy turned out to be false, I'd pretty much just shrug and go on with my day. Isotropy doesn't have any especial weight to me, purely because of its origins as an assumption, not conclusion.
I think the larger ramifications are interesting, but don't stick out to me what we're talking flat earth because that's going to come with its own host of knock-on effects right from the get-go.

I would say that without the model being more fleshed out, it can be hard to say exactly what those contradictions are. e.g. are thing which are thought of as contradictions actually contradictions or just not understanding the model.
But you are probably right that some things, like the effect of the pressure gradient, are probably more important than the question of why down.

Agreed on this. I think isotropy has that immediacy, but lacks the persuasive power, to me. Objections have more persuasive power, but also more room for responses.

I would say the reasoning holds regardless of what force is being discussed. Not only would it apply to gravity, it would also apply to electromagnetism, or even simpler things like pushing on things.
You have an object B applying a force to a measuring device.
You then introduce another object A, which makes contact with B, but which does not apply a force to B, yet somehow the force B applies to the measuring device increases.
The question is where is this force coming from?

Ah, I think a better way of putting what I was trying to say is:
The question of how a force is transmitted from the ball, to the water, to the jug, to the scale only seems to me to make sense if we're talking about something analogous to gravity. My understanding of the model though, is that it's maybe better to view this not as an interaction between the ball and the water, but between the ball/water/jug, and the less dense air surrounding them - that is, after all, in the model the instigating factor for perceived weight. So even if the ball exerts no force on the jug, the density atop the scale has increased strictly from the interaction between the ball and air - and if we simplify this to just talk about the jug on the scale, in that situation it was the relatively density of the jug and air that led to weight registering on the scale, not the jug itself getting pushed down.
I think what can be the issue is, like, you don't accept density as causing such a force for separate reasons - which, sure, but it makes the ball example feel superfluous. If we grant density as a relevant factor, then it follows to me that a buoyant ball will still increase the density of a system and thus cause more force, but that doesn't itself mean density would function in this way. Just a matter of untangling objections.
That is, if you grant for the purposes of a hypothetical that a jug being denser than the air means it will register a weight on a set of scales, then a ball increasing the density of the system ought to do the same, as the relative density is the key factor, not a chain of forces acting down from ball to water to jug to scale. It'd be the equivalent of replacing the liquid in the jug with a heavier liquid - actually maybe the jug itself is a simpler example? Presumably a liquid in said jug would exert no force on the jug by the same token, so the ball is again superfluous, just because it's way easier to talk about just a liquid in a jug.

On density itself, I think that can depend. The only way I can see this working is with respect to overall density - like, the most dense thing is going to be a fraction of an atom. It has as much mass as it is ever possible to have in such a space, over the entirety of a volume. However, we still register different densities in an overall object. You could hypothetically have a thin sheet of something dense, like lead, and something less dense but larger above it, and the overall density of the system above the lead could snap it even without active momentum, because you'd have to not just compare the density of the lead and the object, but the density of lead and the surrounding space with that of the object.
Or maybe a better analogy would be the same element, just solid in one, and irregular in another - the irregular object would have less density even if the molecular density is the same. The only way I can see to make sense of it is assuming density as not strictly contained by the objects themselves, but those chemical bonds would enter into it just as a resisitive force that holds an object together when various parts might otherwise fall at a different rate.
...Yeah putting this into words is tricky.

I think that's more a matter of taste than anything. You always run into those "What's more likely, A or B?" situations, especially in speculative stuff, and a lot of the time it's not based on anything concrete. If isotropy turned out to be false, I'd pretty much just shrug and go on with my day. Isotropy doesn't have any especial weight to me, purely because of its origins as an assumption, not conclusion.
I think the larger ramifications are interesting, but don't stick out to me what we're talking flat earth because that's going to come with its own host of knock-on effects right from the get-go.

But a lot of science relies upon those what's more likely?
For example what's more likely a GC solar system with epicycles and so on, or a HC solar system?

And yes, a FE can come with its own ramifications, and its own what's more likely question.
What's more likely, that there is a universal down, and in addition to that we also have something causing things like the cavendish experiment, and something causing the sun to spiral around, and bendy light to make things disappear from the bottom up, and so on. Or is Earth round, with gravity causing things to fall, Earth to orbit the sun, and so on, with light travelling mostly in a straight line with the curvature of Earth causing objects to disappear from the bottom up.

The question of how a force is transmitted from the ball, to the water, to the jug, to the scale only seems to me to make sense if we're talking about something analogous to gravity. My understanding of the model though, is that it's maybe better to view this not as an interaction between the ball and the water, but between the ball/water/jug, and the less dense air surrounding them - that is, after all, in the model the instigating factor for perceived weight. So even if the ball exerts no force on the jug, the density atop the scale has increased strictly from the interaction between the ball and air - and if we simplify this to just talk about the jug on the scale, in that situation it was the relatively density of the jug and air that led to weight registering on the scale, not the jug itself getting pushed down.
I think what can be the issue is, like, you don't accept density as causing such a force for separate reasons - which, sure, but it makes the ball example feel superfluous. If we grant density as a relevant factor, then it follows to me that a buoyant ball will still increase the density of a system and thus cause more force, but that doesn't itself mean density would function in this way. Just a matter of untangling objections.
That is, if you grant for the purposes of a hypothetical that a jug being denser than the air means it will register a weight on a set of scales, then a ball increasing the density of the system ought to do the same, as the relative density is the key factor, not a chain of forces acting down from ball to water to jug to scale. It'd be the equivalent of replacing the liquid in the jug with a heavier liquid - actually maybe the jug itself is a simpler example? Presumably a liquid in said jug would exert no force on the jug by the same token, so the ball is again superfluous, just because it's way easier to talk about just a liquid in a jug.

This comes down to what you consider to be the system. I would say the foam ball decreases the density but increases the size.

But yes, the foam ball is somewhat superfluous, as there is still the question of where this downwards force comes from in the first place, and you can show the problem with an object less dense than steel sitting on the plate of a steel scale with steel springs.
Hence, probably best to wait for an explanation of the force in the first place.

But a lot of science relies upon those what's more likely?
For example what's more likely a GC solar system with epicycles and so on, or a HC solar system?

I don't know that I would agree with that comparison. Two theories supported by evidence can be compared with respect to the quality of that evidence - what are the predictions made, how much goes unexplained, how much is assumed? Isotropy is an assumption. Comparing an assumption to a hypothesis doesn't carry with it the same easy comparison.
Like, even beyond the fact isotropy is questioned, I wouldn't necessarily count it as even a core assumption. If she was coming for homogeneity, I think you'd have more of an argument as 'The laws of physics can change depending on time/location' would kill any attempt to derive an empirical system when different experiments for the same thing might have different causes, etc - but even then, that doesn't make it true, and they are ideals that have been criticised. Plus, so long as the violations are constant or predictable, science remains possible so there seem to be minimal negative consequences, and assumptions carry no evidential weight to me.

And yes, a FE can come with its own ramifications, and its own what's more likely question.
What's more likely, that there is a universal down, and in addition to that we also have something causing things like the cavendish experiment, and something causing the sun to spiral around, and bendy light to make things disappear from the bottom up, and so on. Or is Earth round, with gravity causing things to fall, Earth to orbit the sun, and so on, with light travelling mostly in a straight line with the curvature of Earth causing objects to disappear from the bottom up.

My stance is always that even if we grant for the purposes of argument that the Earth is flat, it's never going to replace RET in our lifetimes because there's simply too much for it to do. Total theory comparison is just never going to be feasible, hence my willingness to focus on it piece by piece.
Like, if we find a fully working, mathematical model for what brings things down, for eclipses, for tides and weather patterns, for the horizon etc etc, you'd then have to bring them all under the same model, and then untangle conspiracy elements and find areas it works better and...

This comes down to what you consider to be the system. I would say the foam ball decreases the density but increases the size.

I'm viewing this more continuously - if we shift to gravity for a second, and we have a ball held above a table, while the gravitational interaction between the two is minimal, it exists - the table has an effect on the ball pulling the ball down, and the ball pulling the table up, albeit insignificantly. At the same time, the air has its even more minimal force - the air behind the ball is also acting on the table, the air in front of the ball acting on the ball in the direction of the table, etc.
Similarly, the air that would take the place of the ball in the jug-and-density scenario could still be modelled as part of the system - the air is sorting itself out with respect to density too. It just obviously isn't any denser than itself, so there's no need to incoporate it.
But taking it your way as well, it's fair to say that the density of the system is increased by more than its size, just by comparing the ball to the air, so that seems functional too.

But yes, the foam ball is somewhat superfluous, as there is still the question of where this downwards force comes from in the first place, and you can show the problem with an object less dense than steel sitting on the plate of a steel scale with steel springs.
Hence, probably best to wait for an explanation of the force in the first place.

I think a compressed spring makes sense, the way I said before. Rote comparison of the density of the elements involved seems like a too simplistic way of modelling this - after all, you can take a spring of solid steel, and a cube of the same amount of steel, just solid, and it's clear that the cube would be denser even if they're both steel. An object less dense than steel, can still end up more dense than a steel spring.
Ditto, a steel plate on a spring, the overall system of the plate and springs could hypothetically be lense dense than a material less dense than steel itself, just because there are gaps. Volume will always be a factor.
The issue I do see tripping this model up is the lack of a reaction force from an object at rest, so I understand you there, and that seems to be where the biggest problem arises, but I do think there are doors available - or at least avenues for experimentation.

Quote from: JackBlack on December 11, 2022, 02:12:41 PM

But a lot of science relies upon those what's more likely?
For example what's more likely a GC solar system with epicycles and so on, or a HC solar system?

I don't know that I would agree with that comparison. Two theories supported by evidence can be compared with respect to the quality of that evidence - what are the predictions made, how much goes unexplained, how much is assumed? Isotropy is an assumption. Comparing an assumption to a hypothesis doesn't carry with it the same easy comparison.

What is a hypothesis but an assumption?
What is the distinction between assuming isotropy with gravity provide the direction, vs assuming a significant anisotropy and having that anisotropy being why things fall?

At best, unexplained anisotropy would be equal to an assumption of isotropy.

Like, even beyond the fact isotropy is questioned, I wouldn't necessarily count it as even a core assumption. If she was coming for homogeneity, I think you'd have more of an argument as 'The laws of physics can change depending on time/location' would kill any attempt to derive an empirical system when different experiments for the same thing might have different causes, etc - but even then, that doesn't make it true, and they are ideals that have been criticised. Plus, so long as the violations are constant or predictable, science remains possible so there seem to be minimal negative consequences, and assumptions carry no evidential weight to me.

My issue is that if the universe is anisotropic, having preferred directions, then it seriously raises the question of if there are preferred times or preferred locations.
If we don't have isotropy, why assume homogeneity?

I'm viewing this more continuously - if we shift to gravity for a second, and we have a ball held above a table, while the gravitational interaction between the two is minimal, it exists - the table has an effect on the ball pulling the ball down, and the ball pulling the table up, albeit insignificantly. At the same time, the air has its even more minimal force - the air behind the ball is also acting on the table, the air in front of the ball acting on the ball in the direction of the table, etc.
Similarly, the air that would take the place of the ball in the jug-and-density scenario could still be modelled as part of the system - the air is sorting itself out with respect to density too. It just obviously isn't any denser than itself, so there's no need to incoporate it.
But taking it your way as well, it's fair to say that the density of the system is increased by more than its size, just by comparing the ball to the air, so that seems functional too.

My issue with this line of thinking is why include the air where the foam ball would be? If we are going to include the air, why not include the air all the way up to space, making it certainly less dense than the scale below.

I think a compressed spring makes sense, the way I said before. Rote comparison of the density of the elements involved seems like a too simplistic way of modelling this - after all, you can take a spring of solid steel, and a cube of the same amount of steel, just solid, and it's clear that the cube would be denser even if they're both steel. An object less dense than steel, can still end up more dense than a steel spring.
Ditto, a steel plate on a spring, the overall system of the plate and springs could hypothetically be lense dense than a material less dense than steel itself, just because there are gaps. Volume will always be a factor.
The issue I do see tripping this model up is the lack of a reaction force from an object at rest, so I understand you there, and that seems to be where the biggest problem arises, but I do think there are doors available - or at least avenues for experimentation.

The issue is if you aren't just going to focus on the steel of the spring, what do you include, and why? Should you include just the air contained within a cylinder bounding the spring, or the air over the entire layer of Earth, or somewhere in between?

And while it is hypothetically possible for this expanded idea of the steel spring being an entire cylinder to be less dense than an object placed on it, it is also possible to go the other way and have it more dense, at least if you limit it to the cylinder, and even more so if you make the spring out of a denser material.

What is a hypothesis but an assumption?
What is the distinction between assuming isotropy with gravity provide the direction, vs assuming a significant anisotropy and having that anisotropy being why things fall?

At best, unexplained anisotropy would be equal to an assumption of isotropy.

I'd agree with 'at best,' though I'd hold that the assumption of isotropy can never be stronger than a hypothesis - it'd be an untestable statement, which would be how I'd characterise the difference between an assumption and a hypothesis. A hypothesis can make predictions, and be made stronger, while an assumption will only ever be an assumption.

Losing isotropy is perfectly possible - so's losing homogeneity for that matter. I'd argue they are distinct, but I'd also never hold them as on the same level as a theory or law. If we find evidence that goes against them, which is possible, then we'd need to live with it. There might be issues if the violations were infrequent or inconsistent - which doesn't seem to be proposed here - but even then it would still be a fact. The only real difference would be that science would become more explicitly centred on probability.

The issue is if you aren't just going to focus on the steel of the spring, what do you include, and why? Should you include just the air contained within a cylinder bounding the spring, or the air over the entire layer of Earth, or somewhere in between?

I think that's just part of what you have to deal with when it comes to density. If we only compare the object to an adjacent molecule, well we can always make even a gas denser if we ignore the gaps.
The likely-overcomplicated view I have in my head is centres of density - if we do as you say, and take a system to be literally everything, then sure it would have a centre of density with a value somewhere. Then, if we shrink that range slightly, you'd have a centre/value elsewhere, etc, ditto for whatever tiny sliver was omitted would have its own centre, taking every possible field... There's a hypothetical mean of all of that which would be the net distribution of densities of everything, relative forces etc. That's not remotely going to be the simplest way to tackle this, but it makes a kind of sense in my head.

A simplification I imagine would be treating a system as that which moves together - like, if we take the buoyant ball again, even if we grant no force between the ball and the water, if the jug was lowered an inch then the ball would fall an inch (granting the theory for the purposes of discussion). Meanwhile, if we move the jug down, there'll be no significant effect on the upper atmosphere.
I'd liken it to, under gravity, using the pull of the moon Charon when you drop a tennis ball. Technically speaking there would be an effect, it's just so utterly insignificant we don't bother to include it. So while, sure, yeah, the net density of the entire universe could be modelled for the most overly-stringent view, it would simplify massively on the small scale to just that which moves.
Though I would agree that the 'take the air where the ball could be' isn't a helpful expression for any more than saying that the ball increases volume, and also increases density relative to said air.

And while it is hypothetically possible for this expanded idea of the steel spring being an entire cylinder to be less dense than an object placed on it, it is also possible to go the other way and have it more dense, at least if you limit it to the cylinder, and even more so if you make the spring out of a denser material.

Agreed - though in my mind, this passes from an inherent flaw to a testable prediction.

I'd agree with 'at best,' though I'd hold that the assumption of isotropy can never be stronger than a hypothesis - it'd be an untestable statement, which would be how I'd characterise the difference between an assumption and a hypothesis. A hypothesis can make predictions, and be made stronger, while an assumption will only ever be an assumption.

I would say it can be tested, by performing tests of various things in various directions.
The assumption of isotropy predicts that the results will be the same regardless of direction chosen, conversely, if it is wrong, you should be able to find the tested thing will vary with direction.

Losing isotropy is perfectly possible - so's losing homogeneity for that matter. I'd argue they are distinct, but I'd also never hold them as on the same level as a theory or law. If we find evidence that goes against them, which is possible, then we'd need to live with it. There might be issues if the violations were infrequent or inconsistent - which doesn't seem to be proposed here - but even then it would still be a fact. The only real difference would be that science would become more explicitly centred on probability.

Yes, losing them is possible. However without knowing how it varies, we wouldn't even know the probabilities.
This would make it quite challenging to make any useful predictions.

I think that's just part of what you have to deal with when it comes to density. If we only compare the object to an adjacent molecule, well we can always make even a gas denser if we ignore the gaps.
The likely-overcomplicated view I have in my head is centres of density - if we do as you say, and take a system to be literally everything, then sure it would have a centre of density with a value somewhere. Then, if we shrink that range slightly, you'd have a centre/value elsewhere, etc, ditto for whatever tiny sliver was omitted would have its own centre, taking every possible field... There's a hypothetical mean of all of that which would be the net distribution of densities of everything, relative forces etc. That's not remotely going to be the simplest way to tackle this, but it makes a kind of sense in my head.

A simplification I imagine would be treating a system as that which moves together - like, if we take the buoyant ball again, even if we grant no force between the ball and the water, if the jug was lowered an inch then the ball would fall an inch (granting the theory for the purposes of discussion). Meanwhile, if we move the jug down, there'll be no significant effect on the upper atmosphere.
I'd liken it to, under gravity, using the pull of the moon Charon when you drop a tennis ball. Technically speaking there would be an effect, it's just so utterly insignificant we don't bother to include it. So while, sure, yeah, the net density of the entire universe could be modelled for the most overly-stringent view, it would simplify massively on the small scale to just that which moves.
Though I would agree that the 'take the air where the ball could be' isn't a helpful expression for any more than saying that the ball increases volume, and also increases density relative to said air.

And I would say going down this route, you end up with a system where for all practical purposes, a force is applied to the object below, even if it is less dense, causing it to be compressed and sag to make the overall system go lower.
Where even if an object was less dense than the spring and air, because the air is moving around the edge, the centre of mass of the overall system would be lower if the spring is compressed allowing the object to move down and the air to move around it.

I would say it can be tested, by performing tests of various things in various directions.
The assumption of isotropy predicts that the results will be the same regardless of direction chosen, conversely, if it is wrong, you should be able to find the tested thing will vary with direction.
...
Yes, losing them is possible. However without knowing how it varies, we wouldn't even know the probabilities.
This would make it quite challenging to make any useful predictions.

I don't quite understand how these reconcile. If we take the assumption to be testable, then we can determine variation. If we don't take the assumptions to be testable, then they lack the weight of hypothesis or theory.
I understand taking them as convenience, even approximation, but no more than that. And certainly, in this case, the violation of isotropy is defined.

And I would say going down this route, you end up with a system where for all practical purposes, a force is applied to the object below, even if it is less dense, causing it to be compressed and sag to make the overall system go lower.
Where even if an object was less dense than the spring and air, because the air is moving around the edge, the centre of mass of the overall system would be lower if the spring is compressed allowing the object to move down and the air to move around it.

I agree that there's stuff to work out.
I think one can coherently have a point at which the density of the system below would be less than the system above, and so nothing to induce a force. There are concerns in regards to predictions and tests resulting from what it would take for it to work, but in of itself the concerns seem practical more than theoretical.
In that situation, you'd compress a spring enough that its density wasn't greater than the weight above. You'd have to reach that point. There is an interesting question in regards to varying density of the air, but I'm not sure what you're getting at beyond that.

I don't quite understand how these reconcile. If we take the assumption to be testable, then we can determine variation. If we don't take the assumptions to be testable, then they lack the weight of hypothesis or theory.
I understand taking them as convenience, even approximation, but no more than that. And certainly, in this case, the violation of isotropy is defined.

It is possible to test them and find that they are violated, that is that things vary based upon direction/time/location (or some combination thereof), without knowing what the variation is for all possibilities.
For example, if we find that the speed of light is 2.998e8 m/s in one direction, and it is 2.997e8 m/s 10 degrees away from that direction, then what will it be 5 degrees away, or 20, or 10 degrees away in a different direction?
If we find that the speed of light is 2.998e8 m/s today, but is 2.999e8 m/s tomorrow, what will it be 1 week from now?
If we find that it is 2.998e8 m/s where Earth currently is, but is 2.993e8 m/s where Mars currently is, what is it on Venus, or where Earth will be in a week?

In each case, we have determined that there is a variation, however we haven't obtained how it varies through direction/time/space.

And it can even be challenging to determine what has actually be shown to vary. Time or direction is the most obvious to potentially rule out by conducting simultaneous measurements or measurements in the same direction to indicate that it varies based upon something else, but you can't have the test in the exact same location testing different directions at the same time. And due to the motion of everything, and the issue of relativity, there is the question of if testing at different times will be the same location or different locations. But even that leaves open the possibility of it varying based upon multiple things.

And in this case, while there would be a somewhat defined variation in direction, causing things to go down, there would also be a variation in location as the rate of acceleration varies with location.

I think one can coherently have a point at which the density of the system below would be less than the system above, and so nothing to induce a force. There are concerns in regards to predictions and tests resulting from what it would take for it to work, but in of itself the concerns seem practical more than theoretical.
In that situation, you'd compress a spring enough that its density wasn't greater than the weight above. You'd have to reach that point. There is an interesting question in regards to varying density of the air, but I'm not sure what you're getting at beyond that.

I assume you mean that the other way around, that the density below is greater than or equal to the system above.
That inducing a force or not has complications with the force that would be trying to oppose it.
e.g. if it didn't induce a force, then the spring should oscillate, as it reaches a point where the spring results in an upwards force with nothing to counter it.

But as for the main idea, regarding the ball in the jug vs the water in the jug vs just the jug and what to consider as the system for discussion of density, you had stated that the upper atmosphere doesn't really matter as the jug lowering wouldn't effect it.
However the atmosphere below the jug (or part thereof) would be affected as it would need to move around and go above the jug.
But the steel spring would compress with the top going down.
So the question is would it be better to consider the centre of mass rather than density.

In each case, we have determined that there is a variation, however we haven't obtained how it varies through direction/time/space.

And it can even be challenging to determine what has actually be shown to vary. Time or direction is the most obvious to potentially rule out by conducting simultaneous measurements or measurements in the same direction to indicate that it varies based upon something else, but you can't have the test in the exact same location testing different directions at the same time. And due to the motion of everything, and the issue of relativity, there is the question of if testing at different times will be the same location or different locations. But even that leaves open the possibility of it varying based upon multiple things.

And in this case, while there would be a somewhat defined variation in direction, causing things to go down, there would also be a variation in location as the rate of acceleration varies with location.

One could also propose a different mechanism. If light seems to be a different speed one direction to another, that might be in response to something that exists one way and not the other that has some effect on light.
Which just gets to the same 'It can be hard to determine what varies.' I don't see that as anything unique to isotropy, it's just one of the tricky bits of science. If we made that observation, we'd assume something exerted some force on light itself, because we assume isotropy and homogeneity, but it'd still just be assumption. If we assume isotropy in all directions except one, that remains defined still, so science remains possible.

I assume you mean that the other way around, that the density below is greater than or equal to the system above.
That inducing a force or not has complications with the force that would be trying to oppose it.
e.g. if it didn't induce a force, then the spring should oscillate, as it reaches a point where the spring results in an upwards force with nothing to counter it.

Thanks for catching, did write that when tired.
I'd agree, but I'd also hold that the spring's oscillations would tend towards minimal - it'd allow a force-reading when compression is read anyway, but it can't go too far either side of balanced.

But as for the main idea, regarding the ball in the jug vs the water in the jug vs just the jug and what to consider as the system for discussion of density, you had stated that the upper atmosphere doesn't really matter as the jug lowering wouldn't effect it.
However the atmosphere below the jug (or part thereof) would be affected as it would need to move around and go above the jug.
But the steel spring would compress with the top going down.
So the question is would it be better to consider the centre of mass rather than density.

Just comes down to how much of a factor volume is, really. There are interesting applications there - especially if mass is still a factor when determining momentum. Mass certainly seems to matter, just not necessarily on specifically the originating downwards component of why things fall.

I agree with most of what you said, so I'll just quote the parts I want to comment on.

One could also propose a different mechanism. If light seems to be a different speed one direction to another, that might be in response to something that exists one way and not the other that has some effect on light.

Yes, or it could be the speed of light varying with location, and it just happens that the directions you have chosen overlap with those locations.

And yes, it can be difficult to determine if any anisotropy (or other variation) is due to variations in the laws of nature, or variations in what is present.

If we assume isotropy in all directions except one, that remains defined still, so science remains possible.

I would say if we find that isotropy is violated, there would be no reason to assume isotropy in all directions except that, and instead I would be more inclined to say we need to measure in every direction.

Yes, or it could be the speed of light varying with location, and it just happens that the directions you have chosen overlap with those locations.

And yes, it can be difficult to determine if any anisotropy (or other variation) is due to variations in the laws of nature, or variations in what is present.

I think we're agreed on this too.

I would say if we find that isotropy is violated, there would be no reason to assume isotropy in all directions except that, and instead I would be more inclined to say we need to measure in every direction.

I guess this would come down to what you view the purpose of the isotropy assumption as - as a convenience/simplification to make derivations easier, or as something with inherent truth value.
I'd argue that the idea of one direction being special has no inherent implication as to other directions - and that this is the equivalent to asserting isotropy in the first place. With no reason to assume zero directions are special beyond practical concerns, if it is reasonable to do so then it's reasonable to limit it to one. (All this assuming there's no reason to make 'down' stand out)

I guess this would come down to what you view the purpose of the isotropy assumption as - as a convenience/simplification to make derivations easier, or as something with inherent truth value.
I'd argue that the idea of one direction being special has no inherent implication as to other directions - and that this is the equivalent to asserting isotropy in the first place. With no reason to assume zero directions are special beyond practical concerns, if it is reasonable to do so then it's reasonable to limit it to one. (All this assuming there's no reason to make 'down' stand out)

While isotropy is an assumption, I wouldn't necessarily just say it is a convenience. I would more describe it is a key assumption/principle which allows you to take measurements, etc from 1 situation and apply it to another situation to make predictions about what would happen. And this relies upon nothing being special.
But if 1 direction is special, it raises the question of why only this one?
And if you have measurements in 2 directions, which one is the special one?
And as most directions will have a component of that special direction, will that make them special as well?

I would also say that the 2 most rational options are that the direction doesn't matter, so we have isotropy, or the direction does matter, so it should be checked in all directions.

While isotropy is an assumption, I wouldn't necessarily just say it is a convenience. I would more describe it is a key assumption/principle which allows you to take measurements, etc from 1 situation and apply it to another situation to make predictions about what would happen. And this relies upon nothing being special.
But if 1 direction is special, it raises the question of why only this one?
And if you have measurements in 2 directions, which one is the special one?
And as most directions will have a component of that special direction, will that make them special as well?

I would also say that the 2 most rational options are that the direction doesn't matter, so we have isotropy, or the direction does matter, so it should be checked in all directions.

I'd say consistency is the necessary assumption, more than isotropy - like, certainly it leads to isotropy, but one can have 'magnetism is at half strength on Tuesdays' and still coherently understand the universe. Predictability/consistency is the key principle, that's what you need to draw and apply conclusions, isotropy and homogeneity make it easier but if their failures are predictable, science only becomes trickier, not impossible.
For me, I'd hold that as there is no cause for no direction to be special, it isn't inherently preferred. You can argue those two options, but it feels as though that is more intuition than a rational basis. The question of if and why the universe is isotropic is far beyond our usual systems of inquiry. I can see the probabilistic argument, but with so little data that's more opinion than fact.

Quote from: bulmabriefs144 on December 07, 2022, 11:47:37 PM

If you have a computer with a printer, you can digital edit pictures of planets (I've done it unprofessionally before, to show that it can be done) complete with fake moons and satellites.

And you can't say CGI because there is footage of all kinds of zero g acrobatics from SkyLab, predates CGI. And wirework couldn't be it either as their movements wouldn't allow for it. Shots are too long for the vomit comet.





As far as CGI goes, have you ever watched the credits for a heavy VFX movie before? There are 100's of people listed under VFX. 100's.

Take the movie 'The Martian':

2015   The Martian
- VFX Shots: 1100   
- VFX Companies: MPC (425 shots), Framestore (338 shots), Industrial Light & Magic (ILM), Milk Visual Effects, Prime Focus World, The Senate Visual Effects and Territory. 700 artists in total.   
- Production Budget: $108,000,000

That doesn't look inexpensive to me.

You do realise if that supposed microgravity was as real as we are told then the person doing those acrobats would have absolutely no way to stop himself from the spin and could not alternate his body, also.
I can well understand why the average male and female who has taken all this at face value would accept it as being what's told and shown but those who have given it proper thought should see it for the utter silliness it is.

Quote from: Stash on December 08, 2022, 05:43:40 AM

Quote from: bulmabriefs144 on December 07, 2022, 11:47:37 PM

If you have a computer with a printer, you can digital edit pictures of planets (I've done it unprofessionally before, to show that it can be done) complete with fake moons and satellites.

And you can't say CGI because there is footage of all kinds of zero g acrobatics from SkyLab, predates CGI. And wirework couldn't be it either as their movements wouldn't allow for it. Shots are too long for the vomit comet.





As far as CGI goes, have you ever watched the credits for a heavy VFX movie before? There are 100's of people listed under VFX. 100's.

Take the movie 'The Martian':

2015   The Martian
- VFX Shots: 1100   
- VFX Companies: MPC (425 shots), Framestore (338 shots), Industrial Light & Magic (ILM), Milk Visual Effects, Prime Focus World, The Senate Visual Effects and Territory. 700 artists in total.   
- Production Budget: $108,000,000

That doesn't look inexpensive to me.

Trick photography and trick room. They are actually photographed sideways. Fred Astaire, ladies and gentlemen.



Also, there's such a thing as wires and stop-motion animation. CGI can be expensive if you outsource it. You can also do it for free with programs like GIMP and animation. If China can routinely churn out wuxia stuff, there are definitely ways to do stunts like this.

Bravo.
It's pretty clear to anyone who wishes to see that there is a lot of dodgy stuff going on with this space bull.

Quote from: Stash on December 08, 2022, 05:43:40 AM

Quote from: bulmabriefs144 on December 07, 2022, 11:47:37 PM

If you have a computer with a printer, you can digital edit pictures of planets (I've done it unprofessionally before, to show that it can be done) complete with fake moons and satellites.

And you can't say CGI because there is footage of all kinds of zero g acrobatics from SkyLab, predates CGI. And wirework couldn't be it either as their movements wouldn't allow for it. Shots are too long for the vomit comet.





As far as CGI goes, have you ever watched the credits for a heavy VFX movie before? There are 100's of people listed under VFX. 100's.

Take the movie 'The Martian':

2015   The Martian
- VFX Shots: 1100   
- VFX Companies: MPC (425 shots), Framestore (338 shots), Industrial Light & Magic (ILM), Milk Visual Effects, Prime Focus World, The Senate Visual Effects and Territory. 700 artists in total.   
- Production Budget: $108,000,000

That doesn't look inexpensive to me.

You do realise if that supposed microgravity was as real as we are told then the person doing those acrobats would have absolutely no way to stop himself from the spin and could not alternate his body, also.

Why?

Same concept:

Quote from: JackBlack on December 14, 2022, 12:41:55 AM

While isotropy is an assumption, I wouldn't necessarily just say it is a convenience. I would more describe it is a key assumption/principle which allows you to take measurements, etc from 1 situation and apply it to another situation to make predictions about what would happen. And this relies upon nothing being special.
But if 1 direction is special, it raises the question of why only this one?
And if you have measurements in 2 directions, which one is the special one?
And as most directions will have a component of that special direction, will that make them special as well?

I would also say that the 2 most rational options are that the direction doesn't matter, so we have isotropy, or the direction does matter, so it should be checked in all directions.

I'd say consistency is the necessary assumption, more than isotropy - like, certainly it leads to isotropy, but one can have 'magnetism is at half strength on Tuesdays' and still coherently understand the universe. Predictability/consistency is the key principle, that's what you need to draw and apply conclusions, isotropy and homogeneity make it easier but if their failures are predictable, science only becomes trickier, not impossible.
For me, I'd hold that as there is no cause for no direction to be special, it isn't inherently preferred. You can argue those two options, but it feels as though that is more intuition than a rational basis. The question of if and why the universe is isotropic is far beyond our usual systems of inquiry. I can see the probabilistic argument, but with so little data that's more opinion than fact.

The issue is if their failures are predictable.
If we are already making exceptions for Tuesday, why not other days, or particular years?
I see it as if it is already changing based upon time, I see no reason for it to not change more.

You do realise if that supposed microgravity was as real as we are told then the person doing those acrobats would have absolutely no way to stop himself from the spin and could not alternate his body, also.

Why?
Can you try to provide a rational justification rather than just a baseless assertion?
Have you seen a cat in free fall spin itself around?

As a human, they have muscles. These muscles apply forces to various parts of the body to make them move relative to other parts.
This allows them to move their body around.
Another key part here is conservation of angular momentum.
If you take an object that is spinning, and increase its moment of inertia (such as by moving some mass outwards) the rate of rotation will decrease.

So when they are in a ball and spinning quickly, why shouldn't they be able to straighten out their body, decreasing their momentum of inertia and slowing down their spin?

I can well understand why the average male and female who has taken all this at face value would accept it as being what's told and shown but those who have given it proper thought should see it for the utter silliness it is.

Quite the opposite.
I can well understand that those who don't want there to be space can happily dismiss it as fake and come up with simple excuses as to why it must be fake.
But those who have given it proper thought can't find fault with it, but can find fault with the excuses provided.
Those who have given it proper thought recognise that the most likely option by far is that there are things in space.

Bravo.
It's pretty clear to anyone who wishes to see that there is a lot of dodgy stuff going on with this space bull.

You mean it is pretty clear to anyone who honestly examines it that FEers and the like are incredibly desperate with their attempts to dismiss things related to space as Fake.
They will come up with whatever excuses they can, regardless of how poorly they work.
And then other like minded FEers will happily accept those excuses without thinking about just how poorly they work.
Look at you here, happily commending an excuse which clearly doesn't work.
Where even a tiny bit of thinking would have you realise it doesn't work.
But because you want space to be fake, you will happily accept it.

Why don't you try explaining how a room where they rotate it to make it look like you appear to be walking on a wall in any way helps to fake 0 g?

Quote from: Slime on December 14, 2022, 04:30:16 AM

Quote from: JackBlack on December 14, 2022, 12:41:55 AM

While isotropy is an assumption, I wouldn't necessarily just say it is a convenience. I would more describe it is a key assumption/principle which allows you to take measurements, etc from 1 situation and apply it to another situation to make predictions about what would happen. And this relies upon nothing being special.
But if 1 direction is special, it raises the question of why only this one?
And if you have measurements in 2 directions, which one is the special one?
And as most directions will have a component of that special direction, will that make them special as well?

I would also say that the 2 most rational options are that the direction doesn't matter, so we have isotropy, or the direction does matter, so it should be checked in all directions.

I'd say consistency is the necessary assumption, more than isotropy - like, certainly it leads to isotropy, but one can have 'magnetism is at half strength on Tuesdays' and still coherently understand the universe. Predictability/consistency is the key principle, that's what you need to draw and apply conclusions, isotropy and homogeneity make it easier but if their failures are predictable, science only becomes trickier, not impossible.
For me, I'd hold that as there is no cause for no direction to be special, it isn't inherently preferred. You can argue those two options, but it feels as though that is more intuition than a rational basis. The question of if and why the universe is isotropic is far beyond our usual systems of inquiry. I can see the probabilistic argument, but with so little data that's more opinion than fact.

The issue is if their failures are predictable.
If we are already making exceptions for Tuesday, why not other days, or particular years?
I see it as if it is already changing based upon time, I see no reason for it to not change more.

If Newtonian mechanics break down at relativistic speeds, why not at slower speeds?
You go with whatever the model predicts. It'd be on the table, but it wouldn't be assumed.

If Newtonian mechanics break down at relativistic speeds, why not at slower speeds?
You go with whatever the model predicts. It'd be on the table, but it wouldn't be assumed.

They do, it is just a question of how much.

e.g. velocity addition (assuming straight line), should be (u+v)/(1+u*v/c^2)

If we have an object a 100 m/s, ejecting another object at 100 m/s relative to it, the speed to an outside observer is 199.999999999978 (with some floating point arithmetic error).
But this means for practical purposes, that error is going to be tiny, so we can simplify and treat it as Newtonian addition.

Quote from: Slime on December 14, 2022, 01:03:39 PM

If Newtonian mechanics break down at relativistic speeds, why not at slower speeds?
You go with whatever the model predicts. It'd be on the table, but it wouldn't be assumed.

They do, it is just a question of how much.

e.g. velocity addition (assuming straight line), should be (u+v)/(1+u*v/c^2)

If we have an object a 100 m/s, ejecting another object at 100 m/s relative to it, the speed to an outside observer is 199.999999999978 (with some floating point arithmetic error).
But this means for practical purposes, that error is going to be tiny, so we can simplify and treat it as Newtonian addition.

Fair enough, but that still suffices for my point - allowing for breakdowns of the assumptions doesn't mean significant ones. You go by what a model predicts (insert rant on the definition of model here because that seems to be what this site does now) rather than assume a specific set of conditions.

Hey Crouton.

You know what would be a good idea?

Banning all the flat earthers from the flat earth society. Then we can discuss science^TM without all this flat earth nonsense.

And it would totally still be the Flat Earth Society then.

Quote from: sceptimatic on December 14, 2022, 06:30:24 AM

Quote from: Stash on December 08, 2022, 05:43:40 AM

Quote from: bulmabriefs144 on December 07, 2022, 11:47:37 PM

If you have a computer with a printer, you can digital edit pictures of planets (I've done it unprofessionally before, to show that it can be done) complete with fake moons and satellites.

And you can't say CGI because there is footage of all kinds of zero g acrobatics from SkyLab, predates CGI. And wirework couldn't be it either as their movements wouldn't allow for it. Shots are too long for the vomit comet.





As far as CGI goes, have you ever watched the credits for a heavy VFX movie before? There are 100's of people listed under VFX. 100's.

Take the movie 'The Martian':

2015   The Martian
- VFX Shots: 1100   
- VFX Companies: MPC (425 shots), Framestore (338 shots), Industrial Light & Magic (ILM), Milk Visual Effects, Prime Focus World, The Senate Visual Effects and Territory. 700 artists in total.   
- Production Budget: $108,000,000

That doesn't look inexpensive to me.

You do realise if that supposed microgravity was as real as we are told then the person doing those acrobats would have absolutely no way to stop himself from the spin and could not alternate his body, also.

Why?

Same concept:

You mean the concept of insanity? Sitting in a chair twirling a bike wheel is quite rightly just as insane as spinning around in a fake room to convince people gravity is real.

Alright, for like the 70th time, not gravity.

Science experiment time again:

I have a clear jar of water. I have in it water up to halfway and three objects: a small kid's block of wood, a small helium balloon, and a small stone. Rock sinks to bottom, block floats, balloon flies.

It tilt it slowly sideways. Nothing changes about these objects, only the direction of bottom in relation to the container.

Quote from: Stash on December 14, 2022, 09:04:49 AM

Quote from: sceptimatic on December 14, 2022, 06:30:24 AM

Quote from: Stash on December 08, 2022, 05:43:40 AM

Quote from: bulmabriefs144 on December 07, 2022, 11:47:37 PM

If you have a computer with a printer, you can digital edit pictures of planets (I've done it unprofessionally before, to show that it can be done) complete with fake moons and satellites.

And you can't say CGI because there is footage of all kinds of zero g acrobatics from SkyLab, predates CGI. And wirework couldn't be it either as their movements wouldn't allow for it. Shots are too long for the vomit comet.





As far as CGI goes, have you ever watched the credits for a heavy VFX movie before? There are 100's of people listed under VFX. 100's.

Take the movie 'The Martian':

2015   The Martian
- VFX Shots: 1100   
- VFX Companies: MPC (425 shots), Framestore (338 shots), Industrial Light & Magic (ILM), Milk Visual Effects, Prime Focus World, The Senate Visual Effects and Territory. 700 artists in total.   
- Production Budget: $108,000,000

That doesn't look inexpensive to me.

You do realise if that supposed microgravity was as real as we are told then the person doing those acrobats would have absolutely no way to stop himself from the spin and could not alternate his body, also.

Why?

Same concept:

You mean the concept of insanity? Sitting in a chair twirling a bike wheel is quite rightly just as insane as spinning around in a fake room to convince people gravity is real.

Alright, for like the 70th time, not gravity.

Science experiment time again:

I have a clear jar of water. I have in it water up to halfway and three objects: a small kid's block of wood, a small helium balloon, and a small stone. Rock sinks to bottom, block floats, balloon flies.

It tilt it slowly sideways. Nothing changes about these objects, only the direction of bottom in relation to the container.

Your experiment makes no sense.

In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important physical quantity because it is a conserved quantity—the total angular momentum of a closed system remains constant. Angular momentum has both a direction and a magnitude, and both are conserved. Bicycles and motorcycles, frisbees,[1] rifled bullets, and gyroscopes owe their useful properties to conservation of angular momentum. Conservation of angular momentum is also why hurricanes[2] from spirals and neutron stars have high rotational.

Its Newtonian, measurable, is calculated, and utilized. Just as an accelerometer in your kindle uses gravity calculations, same goes for angular momentum. engineers use these properties to design and build lots of things. That’s just a cold, hard fact.

Bonus: as mentioned before, the 1973 astronaut in gif #3, a rotating, astair room wouldn’t work, just look at the number of spins he’s doing. No spinning room, no wires, cgi didn’t exist, nothing could replicate that way back then, except 0g. You literally have no counter explanation for it.

You mean the concept of insanity? Sitting in a chair twirling a bike wheel is quite rightly just as insane as spinning around in a fake room to convince people gravity is real.

It demonstrates the concept of conservation of angular momentum.

Alright, for like the 70th time, not gravity.

Repeating the same nonsense wont help you.

It tilt it slowly sideways. Nothing changes about these objects, only the direction of bottom in relation to the container.

You mean the direction towards Earth relative to the container?