Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - xasop

Pages: [1] 2 3 ... 108  Next >
Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 04, 2021, 11:22:43 PM »
Please provide a final and definitive position.
The "position" has been unchanged since long before this thread was created. It is written in the wiki. Your poor understanding of physics is not anyone else's fault.

On FE, can the rate of acceleration and/or the air resistance rate be the same as RE and result in the same fall time or do they have to be different?  Choose wisely, because if they have to be different, the equivalence principle no longer applies.
The question is incomplete. The acceleration of what?

The diver and earth have the same rate of acceleration
Please stop saying this. It has never been true under either RET or FET, it is not true now, and it will never be true.

If you need to use different parameters and calculations for FET and RET, then the equivalence principle doesn't apply.
You don't need to use different parameters for FET and RET. You need to use different parameters if you change your frame of reference.

Have you taken a physics course yet?

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 04, 2021, 11:13:49 PM »
The essence of this discussion was my claim that observer's points of view can not be simply swapped as soon as acceleration is involved. This simple swapping is only allowed when objects are moving frictionless at constant speed. As I pointed out earlier, when acceleration is involved, then the force which is responsible for the acceleration needs to be included in both reference frames. When swapping reference frames or point of observation, that force needs to applied to (and drawn on) the object which really is accelerating.
No, that force is represented by the introduction of a fictitious field, with corresponding potential energy, if the chosen frame of reference is non-inertial. This is true of both RET and FET. Under general relativity, gravity is a fictitious force which compensates for the fact that our measuring instruments experience an upward proper acceleration but no coordinate acceleration.

The RE explanation for this proper acceleration is that following a geodesic in spacetime would lead an object to fall towards the Earth's centre of mass. The Earth is in balance between the natural tendency of matter to follow that geodesic, and the electrostatic repulsion between atoms. The real force at play is electrostatic repulsion pushing the Earth's surface up, but for most practical problems, it makes more sense to ignore general relativity, treat an observer on Earth as stationary, and consider falling objects subject to the fictitious force of gravity within a gravitational field. The existence of this field, and the presence of gravitational potential energy, is entirely due to our choice of a non-inertial frame of reference.

UA works on exactly the same principle. There is no fundamental difference between gravity under general relativity and UA. If you choose a frame of reference that accelerates with the Earth, you create a fictitious gravitational field, and you have to account for gravitational potential energy.

A claims that he is accelerating towards B
If A is accelerating then a force of 2F is needed to accelerate mass 2M with an acceleration rate of a. In order for A to travel distance s towards B, an amount of energy of 2F.s is required.

Now if B claims the he is acclerating towards A
If B would be accelerating, then a force F would be required to create the same acceleration rate 'a' between both. But this requires an amount of energy equal to E = F.s, which is only half of the previous supposecly identical or reciproce situation.
This violates the law of thermodynamics.
No, it does not. At least one of A or B will be experiencing proper acceleration, which requires the use of a fictitious field if you want to consider the problem from that perspective.

So if A (mass 2M) is the body which is accerating then the only correct interpretion for both observers would be:
A claims he's accelrating towards B and B claims that A is accelerating towards B, not the other way round.
No. It is equally valid to choose a frame of reference in which A does not undergo coordinate acceleration. But you cannot change the fact that A is undergoing proper acceleration, in which case B is subject to a fictitious force, and its potential energy within that fictitious field is transformed into kinetic energy.

The laws of physics (and more specifically thermodynamics), are applicable at any given point in time, which means that no matter which point in time (or space) we analyze as seen from no matter which reference frame , the observed result needs to be identical.
There are various cases where different observers see results that are not identical. Special relativity tells us that time, length and even momentum are observer-dependent.

It is not sufficient to only look at start- and end-point or to hope that differences will cancel out over time.
That depends on the context. Earlier, you seemed to be arguing that the Earth would fall out of sync with the sun and moon, in which case long-term and large-scale behaviour is very relevant. It's not clear why else you think anything would need to be "modulated".

(see also my first point) this is correct in practice because indeed the differences are not measurable, let alone sensible. But in theory - and for the sake of reasoning - the motion of these small masses are not negligible.
Indeed, we can reason about them if there is a purpose to it. Is your reasoning going anywhere?

..and that its change in velocity over that time is assumed to be constant in this model, so the kinetic energy accumulated is constant by E_k%20%3D%20%5Ctfrac%7B1%7D%7B2%7Dmv%5E2.
The energy fed to the accelerating Earth is not accumuluted at a constant rate. The rate increases over time. in other words: the power which is required to accelerate the Earth increases over time.
Yes and no. I accept that I may not have explained myself clearly, but we seem to be in agreement that this isn't especially relevant. Let me know if you would like me to try a clearer explanation of what I meant.

But essentially this changes nothing to the principle explained.
What principle is that? Are you telling me you can't think of a single natural system that has fluctuating energy output?

No, I claimed that this modulation would be the rather unrealistic consequence.
Do you have any evidence for this claim?

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 04, 2021, 07:14:14 PM »
Are you suggesting that at any given second, the diver and someone on the ground would perceive different distance between the ground and the diver?  Because that is the implication of what you just said.
No, it isn't. Take a physics course.

EDIT: I will also point out that the FET position on UA and Gravity having identical rates of acceleration, like nearly every other FET position on this thread, has changed when somebody finally realizes the original premise doesn’t work.
This has been explained over and over again, despite the fact that it's already in the wiki and we shouldn't need to rewrite it for you. You cannot possibly be this stupid. You have to be trolling.

If you want to say now that UA doesn’t accelerate the diver up at the same rate that gravity would pull him down, that’s fine with me.
What is "now" doing in that sentence? Nobody but you has ever claimed that UA will accelerate the diver up. Once again, you are blaming everyone else involved in this conversation for your errors.

Because then there would be an observable and measurable difference between an earth that is stationary and subject to gravity and an earth that is accelerating up at 9.8.  Just measure the rate at which the skydiver is accelerating.
Relative to what?

The only way a skydiver and the earth that are moving in the same direction will meet in the same time frame as a skydiver that is accelerating toward a stationary earth is if the rate of acceleration is different or the air resistance is different (or some combination of both)
Moving in the same direction relative to what? The rate of acceleration of what is different from what? I keep asking you to describe your model and you keep refusing to do so.

For the love of God, take a physics course and then come back.

Assert what?  Xasop is the one who stated that initial parameters depend on frame of reference.  If that is the case, frame of reference determines the fall time.
No, that does not follow. Take a physics course.

Your calculations for RET are valid for FET in a non-inertial frame of reference that is accelerating along with the Earth. Why do you feel the need to do the same calculations a different way?

Is the implication that they would not be valid for FET in an inertial frame of reference?
Indeed. You would use different parameters and hence different calculations, and you would get the same fall time at the end. Take a physics course. Please.

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 04, 2021, 04:49:57 PM »
Good grief, do you realize that if they have the same initial velocity, with the same rate of acceleration
They don't have the same rate of acceleration. You have been told this numerous times and even took it into account briefly, and then suddenly forgot all about it.

If you take air resistance into account so that the diver is ascending at a different rate than the earth
No, if they start out accelerating at the same rate (which they don't), then air resistance is irrelevant because the air is accelerating at the same rate as the skydiver, so the skydiver has zero velocity relative to the air.

This is why I keep telling you to define your model. You keep making these random unfounded assertions, and half the time you say somebody else said them when they actually didn't. The purpose of defining a model isn't to ensure your calculations are correct (although it helps), it is to clearly present your understanding of the problem so that other people can follow your reasoning. As of now, you have presented no reasoning and are blaming everyone else for its absence.

This is Xasop telling me that the air resistance should be different in his post #7362
I told you no such thing. Please stop making up lies.

When you guys can agree on what the initial parameters should be
The specific initial parameters will depend on your frame of reference. This is why you need to define your model before you go plugging numbers that make no sense into calculators you don't understand the purpose of.

Thankfully, you do have one set of initial parameters that work. Your calculations for RET are valid for FET in a non-inertial frame of reference that is accelerating along with the Earth. Why do you feel the need to do the same calculations a different way?

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 04, 2021, 01:08:27 PM »
Either way: as a consequence the source which provides energy to the Earth needs to carefully modulate the rate at which it is providing this energy, in order to exactly compensate for every falling object, jumping animal, swinging pendulum etc... on Earth.
No, it would not. This is sort of like saying that the Earth should have de-orbited in RET because we launched spacecraft that changed its momentum.

You are talking about minuscule differences by comparison with the total mass of the Earth, and by the law of conservation of momentum, they will not accumulate. A constant force will impart momentum onto the Earth at a constant rate, so the total momentum accumulated over some fixed period of time will always be the same. The easiest way to see this is to model the Earth — including all objects on its surface, whether or not they are falling at any given instant — as a particle at the centre of mass. As long as falling objects fall back to Earth (as opposed to, say, over the edge), any variations in velocity relative to the sun and moon over time would be both temporary and negligible.

A similar argument applies in the case where the force varies and the acceleration is constant, in that the total kinetic energy accumulated by the Earth over a long period of time would not change, even if there are negligible temporary variations. To see this, consider that the total mass of the Earth does not change from the start to the end of some long period of time (although it may vary between these points), and that its change in velocity over that time is assumed to be constant in this model, so the kinetic energy accumulated is constant by E_k%20%3D%20%5Ctfrac%7B1%7D%7B2%7Dmv%5E2.

Distinguishing between these possibilities requires extremely sensitive equipment. Exactly how sensitive cannot be known until we know the total mass of the Earth.

And this is not even the most worrying part of the story because not only the magnitude of the net force 'F' needs to be carefully modulated, also the point where it is acting needs to be carefully positioned.
Any shift of mass on Earth (eg: massive amount of water shifted due to a tsunami, a heavy storm or tides) will require that the magnitude of the distributed forces will have to be modulated locally (directly underneath that shifted mass), in order to keep the resulting net force exactly in the center of mass of the system.
You keep describing the motive force behind UA as though it were intelligently "modulating" itself. That is rather intellectually dishonest, since nobody has suggested that to be the case. Your lack of imagination does not imply intelligent design.

First of all, the line of action of the force does not need to be exactly at the centre of mass. It only needs to be self-correcting — a level Earth must be a stable equilibrium point, so that any tilt causes the Earth to become level again. There are various possible explanations for this.

The Davis plane is one possibility, as you have noted. Another possibility is that the base of the Earth is fluid or semi-fluid, and that when the Earth tilts, matter on the "heavy" side gets pushed towards the "light" side by UA to correct the balance. Or perhaps it is the case that UA produces constant acceleration with variable force — as I said, distinguishing between constant acceleration and constant force is not easy with an object as massive as the Earth.

Suffice it to say that we don't know all the answers, but that is not the same thing as an answer not existing. RET has "dark matter" as its placeholder name for a phenomenon with an unknown cause; FET has UA.

Without this compensation, a momentum would be created with a tilt as a result.
I assume that by "momentum" you mean "torque". I would ask that you be precise with terminology, as it is very easy to confuse the issue by using the wrong words in physics.

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 04, 2021, 08:10:54 AM »
Air resistance for what?  If the skydiver is stationary in FET, there is no air resistance with respect to him.
So you still haven't grasped the concept of velocity being relative. This forum is not a physics course. If you don't understand the basics, I'm sure your local university can help.

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 03, 2021, 09:12:06 PM »
1: The energy source keeps pushing the Earth up with the same force 'F', but since 'm' has decreased a bit, this means that 'a' has to increase with repect to ´a´ in situation 2. So the Earth accelerates at a slightly higher rate and thus travels a longer distance, meaning the the amount of energy pumped into the system is now bigger than in situation 2: F.s1 > F.s2. This violates the law of conservation of energy.
It does not. If you are pushing a trolley with a brick on it using a constant force, and somebody lifts the brick away, the acceleration of the trolley will increase and you will impart more kinetic energy onto the trolley. It doesn't violate the law of conservation of energy because there is no rule that says the transfer of energy must occur at a constant rate.

Your remark is correct (and interesting!), but since we're discussing the FET, in which gravity is forbidden, I'm not counting this as an example. Which concept exists in FET, that allows for contactless transfer (and transformation) of energy?
I never said this does happen in FET. Indeed, I pointed out that it isn't necessary here. But you called the phenomenon "a bit strange", which it isn't.

Your response 'correct' is a bit confusing me . Do you really agree that the energy source which accelerates the Earth (eg 'dark energy') has zero impact on the object which is ´falling´, regardless of its substance (eg: water, steel,...)?

And yes I read the Wiki. I have read quite a number of topics on this wiki. I think you are well aware of that.  ;).
Then you have surely read this part:
The mass of the earth is thought to shield the objects atop it from the direct force of UA.

On FE, If the diver is stationary at a height of 533.7 with respect to an earth that is accelerating towards it at 9.8, the earth will meet him at 10.433s.
Did you account for air resistance? Your calculations for RET include air resistance, so you should be consistent.

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 03, 2021, 01:12:42 PM »
The ball(water) has a certain amount of potential energy, which is in direct relation to the height above the earth
No force is acting upon the ball (water) so this object is not gaining any kinetic energy, but it's losing its potential energy because it is approaching the ground.
Potential energy within what field? What are you basing these claims on?

But this can only be true if we assume 2 things
- (potential) energy from one object can be transferred to another object without both objects touching each other.
This assumption is not required here, although it shouldn't be considered strange as the idea of contactless energy transfer is an established part of RET. It is the basis of gravitational slingshots, for example.

- the force which propels the Earth has zero impact on the steel ball/water during its 'fall'.
Correct. You did read the wiki article on UA before jumping in and claiming to understand what's going on, right?

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 03, 2021, 11:38:42 AM »
Assuming that the Earth is moving up:
In that case the force which propels the Earth must be included in the reference frame (and in the closed system) and also energy source needs to be included, otherwise it's not a closed system because you would be adding external energy.
"Included in the reference frame" makes no sense. A frame of reference doesn't include objects or forces, it is a coordinate system used to describe those things.

But you are otherwise correct that an accelerating Earth is not, by itself, a closed system. You have yet to explain how you got from here to asserting that it is not the case.

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 03, 2021, 11:07:53 AM »
That's what 'removing the background' means. You look at the ball and the feather and remove the background. So you've got only the ball and the feather and no other reference. So you can't tell whether they are moving or not.
No, it isn't. That contributes nothing to the conversation because everyone involved acknowledges that there is motion.

Net energy must be zero, overall.
Within a closed system, yes. How do you get from there to concluding that the Earth is not accelerating up?

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 03, 2021, 10:48:25 AM »
If you include the earth in the system (still ignnoring the rest of the background) then it becomes very apparent that they are falling (accelerating) towards the earth and not the other way round.
You wrote a lot of words but completely failed to explain why you believe this.

Where is the South Pole in the FE model? Most FE models have the wall of ice surrounding the earth, so is the South Pole somewhere along that perimeter?
The "south pole" is a RET concept that corresponds to a circle in FET, centred on the north pole, with twice the radius of the equator. In that sense, it is not really a pole in FET.

If so then if you head due south in it’s direction then once you get past the South Pole you would surely just fly over the edge of the disc, no?
That depends on where the edge is, or if there even is one. The region beyond 90°S latitude is unexplored. It is possible that the frozen wastelands of Antarctica continue for many thousands of kilometres beyond that.

Its exactly the same topic.  The route is what is needed for a round death, not a flat earth.  The fact that it did not go directly over the pole is irrelevant to question of geometry.
I would suggest reading the thread title if you are still confused about the topic of the thread. I'm not going to engage if you are just going to bring up something else every time I ask for evidence you don't have — that would just be an endless game of goalpost-shifting.

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 03, 2021, 06:17:46 AM »
No, every time I have been told that I was calculating wrong, I changed the way I calculated only to be told that I was calculating it wrong and the way I did it at first was the right way.
So where did you account for this in your calculations?
OK, what should the value of the UA force on the skydiver be?
0 N.

Is there some other way of doing it so that the air resistance isn’t the same as it is in RE, but also isn’t different than it is in RE?  You guys need to decide on your story and stick to it.
The "story" is in the wiki, which I have asked you to read several times.

3. You use different values for gravitational/universal acceleration and/or for air resistance and don’t just “change the signs”.
1 and 2 don’t work and 3 confirms what I’ve been saying all along.
UA and the fictitious force of gravity do have equal magnitude and opposite direction, but that is not a difference between RET and FET, it is a difference in frame of reference, as I have already explained. You can select an observer in either theory for whom the Earth is accelerating up, or for whom the skydiver experiences a fictitious downward force.

So, FET does not "flip the signs" because you can perform your calculations using a frame of reference in which they are identical to RET.

According to Duncan and Jack it is.
No, you first posted in this thread before either of them said anything that could be misinterpreted in that way. This isn't the first time you've tried to pin your errors on others. You could have just read the wiki if you want to know how UA works, so "I misunderstood something Duncan said" won't fly.

Everything was calculated assuming a zero acceleration of the skydiver, both UA and gravity.
If you think the skydiver isn't accelerating while in freefall under the influence of gravity, your case is even more hopeless than I thought.

The Qantas Santiago Chile to Aukland NewZealand flight is pretty close.
It was (not is — Qantas has not operated that route in over a year) nowhere near close. At its southermost point, it passed around 4000 km from the south pole.

Why does that flight not fly due west?
Plus there are the many circumnavigations of Antarctica by ship that do not take nearly the needed time to go around the disk of the FE model.
There of course have been many expeditions to Antartica with no evidence of the ice wall that would have to be extremely high (100 mies?) to contain the atmosphere and hence be easy to see.
Irrelevant. If you want to discuss a different topic, you can create another thread for that. Do you have evidence for your claims regarding flying over the south pole or not?

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 02, 2021, 07:21:09 PM »
This shows a downward gravitational force. Are you now acknowledging that the same model, with a fictitious force of gravity, can be used for both FET and RET?
I never denied that is what FET tries to do.  The whole point is that it doesn't work.
How can it not "work" when the calculations are exactly the same in both cases?

Nobody has yet to explain why those numbers are wrong.
Incorrect. It has been explained several times, and every time you ignore it.

You can't just change the signs.
"Changing the signs" is not an accurate summary of UA.

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 02, 2021, 06:05:20 PM »
OK, what should the value of the UA force on the skydiver be?
0 N.

A very simple solution here is for you to show me your calculations.  Using the on-line calculator or not, using whatever numbers you want and show me why your way works.
The most straightforward way to calculate this for FET is using the equivalence principle and the calculations for RET, which you already have.

Yes, actually I did provide one.  A really cute one.  If you think there should be another force included, please let me know.

This shows a downward gravitational force. Are you now acknowledging that the same model, with a fictitious force of gravity, can be used for both FET and RET?

Philosophy, Religion & Society / Re: Coronavirus Vaccine and You
« on: August 02, 2021, 02:30:13 PM »
I just had my second jab. Posting this telepathically over 5G. It was totally worth it.

Flat Earth Theory / Re: Why do objects fall at dofferent speeds?
« on: August 02, 2021, 08:53:39 AM »
How is this wrong?
Because UA does not affect the skydiver directly, only the Earth. Again, please read

The "rate of gravitational acceleration" on includes gravity/UA.  Not any other factors like air resistance.
If the skydiver doesn't move up in FET at the same rate as they would fall down in RET, that implies a difference in the air resistance/thrust.
Are you trolling? You are making no sense at all. First you said your value for upward acceleration doesn't include air resistance, and now you are saying a different upward acceleration means a different air resistance.

Again, have you ever taken a physics course? Do you know how to present a simple mathematical model? You have yet to present a force diagram, yet that is one of the first steps in the process of solving any mechanics problem. You seem to be deeply confused about which forces are acting on the skydiver, which is what a force diagram is intended to clarify.

Philosophy, Religion & Society / Re: Coronavirus Vaccine and You
« on: August 01, 2021, 07:50:07 PM »
It would be a lot easier to reclassify massive media entities like Facebook and YouTube as public utilities and apply government oversight than it would be to play whack-a-mole for every new media monopoly that springs up. You can't easily legislate where people choose to spend time on the internet.
Not directly, no, but most regulations don't apply directly to the thing they're trying to regulate. You don't prevent car accidents by having police be everywhere enforcing the road rules, you reduce the risk by requiring people to take a test to be allowed to drive.

Similarly, there are various indirect methods that could be applied here. A good start would be improved education in technical literacy, so that people understand the difference between the free, decentralised web and an individual private content provider with its own rules. Also, a government-run (or -regulated) search engine that indexes content on private media websites could go a long way to separating content hosting (which there is no need to regulate, beyond banning obviously illegal material) from content discovery (which is currently controlled by the content hosting providers, and that is the problem).

It's a bit defeatist to say "it can't be done" without even trying to solve the problem.

Pages: [1] 2 3 ... 108  Next >