I don't understand the Michelson–Morley experiment

[PeterDonis]

Why you think that circulation theory not get correct lift values?

Correct circulation theory does give correct lift values. But correct circulation theory does not claim that air goes around the wing in a circle. It only says that the circulation of the actual airflow is nonzero and contributes to the lift the wing provides, as I said in post #23.

The "theory" that "air goes around the wing in a circle" does not make correct predictions. But we only know that because we can observe the actual airflow and see that it isn't a circle.

 

[PeterDonis]

There are theories that get same results as GR but use different concepts, teleparallel Gravity (TEGR), Symmetric Teleparallel Gravity (STEGR).

How do you know those "different concepts" are wrong?

Note that (at least AFAIK) teleparallel gravity theories are mathematically equivalent to GR, which is why they all make the same predictions.

 

[Herman Trivilino]

If car travel 100km/h and you trow a ball forward at 10km/h inside the car cabine, ball will always have 10km/h if we measure from car, but we need to measure from outside of car ("rest frame") to ball have 110km/h.

Yes, but suppose you throw the ball at 110 km/h from OUTSIDE the car. That is, relative to the road the car has a speed of 100 km/h and the ball 110 km/h.

What is the speed of the ball relative to the car?

That is the scenario analogous to MM.

Wouldn't you expect it to be 10 km/h?

 

[Dale]

For me space is nothing

There is 1 astronomical unit of space between the sun and the earth.

You can use the word “nothing” to refer to space if you like. That is a reasonable choice. But having made that choice you imply that “nothing” has amounts which can be measured.

You can choose your words, but the facts remain: space can be measured.

so nothing cant be curved

Why not? Space can be measured, so if space is “nothing” then “nothing” can be measured. And since that is the case, why can’t the measurements indicate that it is curved?

I think we still don't know how gravity really works, because we have problems in micro world and large scales.

This is reasonable. Either our knowledge of gravity or our knowledge of matter must be incomplete. Or both, of course.

 

[Nugatory]

For me space is nothing,

Then what does a ruler measure?

 

[A.T.]

I don't understand why people in Michelson-Morley experiment expect that light speed in direction in Earth motion would be light speed + earth speed, if they measure speed from earth frame?

Since light shows some wave-like properties, and for other types of waves their propagation depends on the motion of some medium, they wanted to check if the motion of the Earth relative to such a medium can be detected.

If car travel 100km/h and you trow a ball forward at 10km/h inside the car cabine, ball will always have 10km/h if we measure from car, but we need to measure from outside of car ("rest frame") to ball have 110km/h

That's not how light behaves either, as other observations have shown.
https://en.wikipedia.org/wiki/Emission_theory_(relativity)

 

[A.T.]

For me space is nothing, so nothing cant be curved,

Not being curved but flat is also a geometrical property. Why is it OK to assume that 'nothing' is specifically flat.

 

[Sagittarius A-Star]

For me space is nothing, so nothing cant be curved

Can it be explained without spacetime curvature, that the magnitude of light deflection near the Sun (1.75 arcseconds, as measured 1919 by Eddington) is twice the value, which is predicted by Newton's law of gravity?

 

[Herman Trivilino]

For me space is nothing, so nothing cant be curved, twisted etc etc, so I look this theory as physically incorrect,

In your mind you are debating yourself, which is good. It's a sign of higher order thinking.

But you are creating your own personal straw man argument. You begin with the premise that space is nothing, then go on to draw some false conclusions from that premise.

Your conclusions are wrong because your premise is wrong.

When you have an idea about Nature's behavior that contradicts her actual behavior, then your idea is incorrect.

It has taken our civilization centuries to learn this lesson. Our very lives have been enhanced by the many inventions that have resulted.

 

[gen x]

Then what does a ruler measure?

Ruler show the shortest distance between two object is straight line, and if you are on sphere, drill a tunnel.

Not being curved but flat is also a geometrical property. Why is it OK to assume that 'nothing' is specifically flat.

In your mind you are debating yourself, which is good. It's a sign of higher order thinking.

But you are creating your own personal straw man argument. You begin with the premise that space is nothing, then go on to draw some false conclusions from that premise.

Your conclusions are wrong because your premise is wrong.

When you have an idea about Nature's behavior that contradicts her actual behavior, then your idea is incorrect.

It has taken our civilization centuries to learn this lesson. Our very lives have been enhanced by the many inventions that have resulted.

I just said space is nothing, but if we talk about space as mathematical object then it can be any shape you want in this theory, flat, curved, twisted etc

Einstein quote: "Space and time or spacetime are not conditions of existence but models of thinking"

 

[Ibix]

Ruler show the shortest distance between two object is straight line

So you are assuming your "nothing" obeys Euclidean geometry. Why?

 

[Sagittarius A-Star]

Einstein quote: "Space and time or spacetime are not conditions of existence but models of thinking"

Are you sure the quoted text is from Einstein?
In which paper did Einstein write this?

 

[Nugatory]

Ruler show the shortest distance between two object is straight line, and if you are on sphere, drill a tunnel.

I'm not asking what it shows, I am asking what the thing it measures is. I am trying to get you to reconcile your statement that "space is nothing" when something is being measured by a ruler.

 

[Dale]

I just said space is nothing,

Space can be measured. So if space is “nothing” then “nothing” can be measured. And if “nothing” can be measured then why couldn’t those measurements indicate curvature.

 

[Herman Trivilino]

I just said space is nothing, but if we talk about space as mathematical object [...]

If you "talk about" it as an object, mathematical or otherwise, then you contradict yourself when say it's nothing.

 

[A.T.]

Ruler show the shortest distance between two object is straight line

Grids of rulers can also measure intrinsic curvature, not just distances. If 'nothing' can have measurable distances, then 'nothing' can also have measurable intrinsic curvature.