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**Just Chat! / Re: Mathematics is a decent science.**

« **on:**19/06/2021 09:29:56 »

Hi all,

Beautifully put Alan.

😎

Beautifully put Alan.

😎

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Hi all,

Beautifully put Alan.

😎

Beautifully put Alan.

😎

2

Hi all,

So Colin/Yor on ;

Its funny that there is a potential for different interpretations as to whether mathematics is a science in its own right, I don't know if there is a right or wrong resolution.

https://en.wikipedia.org/wiki/Mathematical_proof

https://en.wikipedia.org/wiki/Pythagorean_theorem

Does the geometry of the physical world cross over the two sides of the debate, or is mathematics purely a language we can utilize to describe/predict physical occurrence in the scientific method ?

https://en.wikipedia.org/wiki/Scientific_method

Either way my dogs can run and jump to catch a tennis ball mid flight without knowing anything about x^2 equations

https://en.wikipedia.org/wiki/Parabola

So Colin/Yor on ;

I think it's a science. It's logic, and that is what we use.Science is supposed to be the investigation of the world around us by observation and experiment.

Not sure logic fits that, pure maths doesn’t.

Maths has lots of proofs, which science doesn’t.

Its funny that there is a potential for different interpretations as to whether mathematics is a science in its own right, I don't know if there is a right or wrong resolution.

https://en.wikipedia.org/wiki/Mathematical_proof

https://en.wikipedia.org/wiki/Pythagorean_theorem

Does the geometry of the physical world cross over the two sides of the debate, or is mathematics purely a language we can utilize to describe/predict physical occurrence in the scientific method ?

https://en.wikipedia.org/wiki/Scientific_method

Either way my dogs can run and jump to catch a tennis ball mid flight without knowing anything about x^2 equations

https://en.wikipedia.org/wiki/Parabola

3

Hi all

So pseudo

Are you meaning frequency or style?

With your original post:

Would relationships be a lot happier, healthier, bountiful, and peaceful if women would cut down on demanding their spouse or partner to change their underwear?

🤔👙🩲😷

So pseudo

Are you meaning frequency or style?

With your original post:

Would relationships be a lot happier, healthier, bountiful, and peaceful if women would cut down on demanding their spouse or partner to change their underwear?

🤔👙🩲😷

4

Hi all

Very good 😌 can you please show your calculations 🧑🎓

Only joking

Wondering how ES is getting along given he said he was calling out the moderators, I feel for him.

I also am going to find the time to read the links Colin provided.

You’re not ignoring the laws of conservation of momentum are you, what’s your coefficients of restitution for these collisions, gasses and solids ?I carefully did not violate momentum conservation. I simply computed the desired momentum and gave that to my small 'meteor'. It's small enough to have no gravitational effect on the experiment before the collision.

I think coefficient of restitution has more to do with collisions between two objects that remain reasonably distinct. So we have two objects before, and a reasonably uniform moving blob of plasma afterwards. Coefficient of e=0 in the ideal case. It doesn't bounce back (e > 0) if that's what you're asking. More like a e<0 (like a human getting hit by a bullet that passes through), which is why I break it up just before collision. I want to move Earth, not shoot a hole through it.

Heck, the whole problem can be solved by having the major mass (sun say) be a black hole. That can't explode when you smack it with something. e=0 necessarily. Fire a small but very high momentum object at it and the black hole will acquire all that momentum without bits flying all over the place. Perfect for our experiment. How long before Earth deviates from its path when the sun abruptly changes velocity by .9c in some direction? GR can answer that because there's no violation of any laws in it, and we don't need to worry about the dynamics of a supernova-scale explosion.

Very good 😌 can you please show your calculations 🧑🎓

Only joking

Wondering how ES is getting along given he said he was calling out the moderators, I feel for him.

I also am going to find the time to read the links Colin provided.

5

Hi all,

So we do seem to be in a pickle, coming up with an alternative thought experiment.

Halc

You’re not ignoring the laws of conservation of momentum are you, what’s your coefficients of restitution for these collisions, gasses and solids ?

ES I don’t understand this:

“More than that under Newtonian gravity we human beings would soon start to see and feel strange gravitational effects (like things falling upward on one side of the planet). While under GR, the paths of objects in free fall won't change for 8+ minutes. “

At what point in proceedings are you anticipating these physical realities

For Newton’s postulate ?

Given Earth is currently, approximately accelerated in its orbit at 6.0 x 10^-3 m/s^2

So we do seem to be in a pickle, coming up with an alternative thought experiment.

Halc

You’re not ignoring the laws of conservation of momentum are you, what’s your coefficients of restitution for these collisions, gasses and solids ?

ES I don’t understand this:

“More than that under Newtonian gravity we human beings would soon start to see and feel strange gravitational effects (like things falling upward on one side of the planet). While under GR, the paths of objects in free fall won't change for 8+ minutes. “

At what point in proceedings are you anticipating these physical realities

For Newton’s postulate ?

Given Earth is currently, approximately accelerated in its orbit at 6.0 x 10^-3 m/s^2

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Hi all

So ES all is good in your world ?

Yanking mass and accelerating it, is a more satisfactory starting point of a thought experiment/analogy?

How does that work exactly ?

What is the string/mechanism going to be attached to, that allows changes in motion/velocity?

Although given Halc stated gravity is not action maybe you can yank this imaginary piece of string without considering the force or energy input required, and any consequences as to where the action / reaction of yanks occur.

But if you’re happy, that’s nice, but I am not to sure how many others you have convinced as to the premise of your irritation and lack of a credible solution 🤔

So ES all is good in your world ?

Yanking mass and accelerating it, is a more satisfactory starting point of a thought experiment/analogy?

How does that work exactly ?

What is the string/mechanism going to be attached to, that allows changes in motion/velocity?

Although given Halc stated gravity is not action maybe you can yank this imaginary piece of string without considering the force or energy input required, and any consequences as to where the action / reaction of yanks occur.

But if you’re happy, that’s nice, but I am not to sure how many others you have convinced as to the premise of your irritation and lack of a credible solution 🤔

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Hi all,

Yes thanks for that Colin, I totally agree, your actually, stating something that was also said in a previous post:

(Energy is the currency of the physical world)

😎

In regards to ES having a problem with the use of a ‘thought experiment/ analogy’ of the Sun disappearance, I believe there are lots of examples of these used through out mans development of theories, and Einstein/Newton are documented to having resorted to using them, to great benefit.

Yes thanks for that Colin, I totally agree, your actually, stating something that was also said in a previous post:

(Energy is the currency of the physical world)

😎

In regards to ES having a problem with the use of a ‘thought experiment/ analogy’ of the Sun disappearance, I believe there are lots of examples of these used through out mans development of theories, and Einstein/Newton are documented to having resorted to using them, to great benefit.

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Hi all

So Alan yes point taken regarding mass and speed of light problem, however isn't whats being discussed the mass/energy equivalence and the empirically tested interaction of photons with a gravity field ?

Think you can put a value on the equivalence substituting hf for E in the famous equation

https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence#Relativistic_mass

Also ES

isn't the Sun disappearing example, just a thought experiment to highlight the difference of Einsteins postulate to Newtons ?

Is there any empirical evidence to support the postulate ?

So Alan yes point taken regarding mass and speed of light problem, however isn't whats being discussed the mass/energy equivalence and the empirically tested interaction of photons with a gravity field ?

Would you care to put a number to the mass of a photon?

Think you can put a value on the equivalence substituting hf for E in the famous equation

https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence#Relativistic_mass

Also ES

Hi everyone.

ii. If the Sun suddenly disappeared, it would take about eight minutes for Earth to become dark (due to the speed of light). How long would it take to feel the absence of the Sun's gravity?, Astronomy magazine, 2012

https://astronomy.com/magazine/ask-astro/2012/05/gravity---the-traveler

isn't the Sun disappearing example, just a thought experiment to highlight the difference of Einsteins postulate to Newtons ?

Is there any empirical evidence to support the postulate ?

9

Hi all,

So we seem to be deviating a little from the OP, but there are definitely areas where Newton gravity and Einstein gravity disagree, and it would seem this discussion is coming up against those areas.

So one question that arises out of the last couple of posts is;

How does GR explain the acceleration that occurs during free fall without a force being a factor and how this reconciles with Newtons three laws of motion ?

So we seem to be deviating a little from the OP, but there are definitely areas where Newton gravity and Einstein gravity disagree, and it would seem this discussion is coming up against those areas.

So one question that arises out of the last couple of posts is;

How does GR explain the acceleration that occurs during free fall without a force being a factor and how this reconciles with Newtons three laws of motion ?

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Hi all,

mmm Jeffery I think you surpass yourself you manage to contradict yourself in one statement:

Do you know what weight is ?

mmm Jeffery I think you surpass yourself you manage to contradict yourself in one statement:

Quote

And the force propagates through the spring. Gravity does that only indirectly. It pulls the weight which changes the stress on the spring. If you were put in place of the weight you would feel the acceleration as the stress on the spring slowed you down. You would not feel this acceleration in free fall. It's force Jim, but not as we know it.

Do you know what weight is ?

11

Hi all,

So Jeffery I believe your last post contradicts your previous post.

As a spring scale follows Hooke’s Law

https://en.m.wikipedia.org/wiki/Hooke's_law

Which measures Force 🤔

So Jeffery I believe your last post contradicts your previous post.

Hi all,

So JefferyWhile you can state F = ma this is not the same as saying F = mg. No force is felt in the second equation. So F ≠ mg.

If what you state is correct, how do my bathroom scales work ?

Your bathroom scales work by preventing gravity from moving an object. The tension in a spring will do it. The tension propagates through the spring until it overcomes gravity. Gravity does not propagate through objects, otherwise you would be able to measure your acceleration during free fall.

Look at the slinky drop video in slow motion and see the tension acting against gravity. It is not gravity propagating through the slinky but the release of tension.

This is why the two Fs in the equation about are not the same. Also why I believe you will never be able to properly measure a difference between m_{i}and m_{g}.

As a spring scale follows Hooke’s Law

https://en.m.wikipedia.org/wiki/Hooke's_law

Which measures Force 🤔

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Hi all,

So Jeffery

If what you state is correct, how do my bathroom scales work ?

So Jeffery

While you can state F = ma this is not the same as saying F = mg. No force is felt in the second equation. So F ≠ mg.

If what you state is correct, how do my bathroom scales work ?

13

Hi all,

So acsinuk

As BC has already stated "They" try to match velocities when docking.

And then Its down to the principle postulated by Galileo of acceleration/velocity of falling bodies is independent of Mass.

https://en.wikipedia.org/wiki/Galileo_Galilei#Falling_bodies

https://www.google.com/search?q=hammer+and+feather+on+the+moon&rlz=1CATTSD_enGB890&oq=hammmer+amd+&aqs=chrome.2.69i57j0i13i433j0i13j46i13i175i199j0i13l2j46i13i175i199j0i13l3.7378j0j15&sourceid=chrome&ie=UTF-8

So acsinuk

But if we delivery a 10 ton payload in a 10 ton transporter parked alongside will the ISS slow down and by how much?? We can assume the ISS weight 400 tons so it increases in combined weight by 5%

As BC has already stated "They" try to match velocities when docking.

And then Its down to the principle postulated by Galileo of acceleration/velocity of falling bodies is independent of Mass.

https://en.wikipedia.org/wiki/Galileo_Galilei#Falling_bodies

https://www.google.com/search?q=hammer+and+feather+on+the+moon&rlz=1CATTSD_enGB890&oq=hammmer+amd+&aqs=chrome.2.69i57j0i13i433j0i13j46i13i175i199j0i13l2j46i13i175i199j0i13l3.7378j0j15&sourceid=chrome&ie=UTF-8

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Hi Phil

The equation and relevant information you require to calculate it is in the link provided

https://www.physicsclassroom.com/class/circles/Lesson-4/Mathematics-of-Satellite-Motion

🤔

The equation and relevant information you require to calculate it is in the link provided

https://www.physicsclassroom.com/class/circles/Lesson-4/Mathematics-of-Satellite-Motion

🤔

15

Opps thought I had left a gap,

Thank you BC

Thank you BC

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Hi all

https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experimenthttp://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/gratim.html

Is there any method that you can think of that could achieve this? Have a stab at it.Similar to the sodium lamp, I believe it would be possible to derive the speed of light using the red/blue shift due to interaction of light with a gravitational field, for example

https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experimenthttp://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/gratim.html

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Good day sport. Evan _au

I believe whichever way you look at it my post is correct,

I will leave you, to go figure. 🙃

I believe whichever way you look at it my post is correct,

I will leave you, to go figure. 🙃

18

Hi all

Humanity wouldn’t last one night !

Humanity wouldn’t last one night !

19

Hi all

now I know there has been a lot of activity and there is certain links I will try to find the time to study, but can we rewind a little So Halc yes I take your point

So I will try to set a scenario that is CMIF and is in touch with reality that we all can relate to.

we have a space ship that is stationary in space, away from any gravitational influence, on this ship is two synchronized atomic clocks with two observers.

The distance between the clocks is 19.62 m the ship accelerates at 9.81 ms^-2 for 2 seconds then decelerates at 9.81 ms^-2 for 2 seconds back to zero

So my back of a fag packet calcs are the observer at the back of the ship will see the clock at the front being 1.07 x 10^-15 sec ahead/faster than his at the 2 sec point and being synchronized again at the four second point.

The question that brings to my mind is what are the clocks actual rate ?

I believe it would be reasonable but happy to be corrected, that for the 2 seconds that they both accelerate they would both slow down by the rate we measure time dilation to be here on earth ( aprox 6.95 x 10^-10 sec/sec) and they would both speed up by the same margin for the 2 sec they decelerate,

hence they are actually synchronized throughout in reality due to their inertial reference frame to each other.

now I know there has been a lot of activity and there is certain links I will try to find the time to study, but can we rewind a little So Halc yes I take your point

Quote

'Come to rest' is dang undefined without frame reference. If the ship is constantly accelerating, then it is gaining speed and not coming to rest. It can cease accelerating and therefore be at rest in its own frame, but the clocks will be very out of sync after that.

So I will try to set a scenario that is CMIF and is in touch with reality that we all can relate to.

we have a space ship that is stationary in space, away from any gravitational influence, on this ship is two synchronized atomic clocks with two observers.

The distance between the clocks is 19.62 m the ship accelerates at 9.81 ms^-2 for 2 seconds then decelerates at 9.81 ms^-2 for 2 seconds back to zero

So my back of a fag packet calcs are the observer at the back of the ship will see the clock at the front being 1.07 x 10^-15 sec ahead/faster than his at the 2 sec point and being synchronized again at the four second point.

The question that brings to my mind is what are the clocks actual rate ?

I believe it would be reasonable but happy to be corrected, that for the 2 seconds that they both accelerate they would both slow down by the rate we measure time dilation to be here on earth ( aprox 6.95 x 10^-10 sec/sec) and they would both speed up by the same margin for the 2 sec they decelerate,

hence they are actually synchronized throughout in reality due to their inertial reference frame to each other.

20

Hi all

Given they have undergone the same velocity and gravitational potential is not a factor.

So if I follow that logic correctly if the clocks were in sync at departure they would be in sync once they/the rocket came to rest in reality ?.

But as far as I know, Einstein never addressed the question of simultaneity-at-a-distance, according to the person who sometimes accelerates.

I'm now thinking that Einstein DID address the question of simultaneity-at-a-distance, according to a person who sometimes accelerates. I remember that Einstein predicted that for two clocks stationary in a gravitational field, the clock higher in the field (farther from the source of the field) will run faster than the clock lower in the field. He got this result long before he published his paper on his GR theory (and long before he arrived at his GR theory). He got it by solving an SR problem, and then invoking his "principle of equivalence" between acceleration and gravitation.

The SR problem he solved was for a rocket, not in the presence of any gravitation field, with a clock at the front and a clock at the back, that is undergoing a constant acceleration. He determined that the clock in front will run faster than the clock at the back. So he DID determine what an accelerating observer at the rear of the rocket will conclude about the current time at the front of the rocket.

I've heard that Einstein wrote a paper in 1907 (2 years after his SR paper, and 8 years before his GR paper) that may have discussed the above result. I'm currently trying to find that 1907 paper (translated into English, of course). I'd like to know if he used CMIF (co-moving inertial frame) simultaneity in getting his result, and whether he made any assumptions in justifying that choice.

Given they have undergone the same velocity and gravitational potential is not a factor.