What is the difference between a preferred state of rest and a preferred state of velocity?

[Simplico]

I am I being stupid, or does special relativity simply substitute the concept of a preferred state of velocity (the speed of light) for the old concept of a preferred state of rest?

[Strange]

2 minutes ago, Simplico said:

I am I being stupid, or does special relativity simply substitute the concept of a preferred state of velocity (the speed of light) for the old concept of a preferred state of rest?

I'm not sure you can compare the two concepts.

If there were a preferred, or absolute, state rest then you could define all velocities relative to that (by using it as a reference to measure all speeds agains).

But you can't use the speed of light as a reference. The speed of light for all observers is the same and so, relative to light (if that means anything) everyone would be moving at the same speed.

But it is the fact that the speed of light is invariant that allows special relativity to solve all sorts of problems by making measurements of space and time relative.

[Simplico]

'He who defends everything defends nothing'. If everyone has their own measure of space and time, does anyone have a measure of anything? 

[koti]

7 minutes ago, Simplico said:

I am I being stupid, or does special relativity simply substitute the concept of a preferred state of velocity (the speed of light) for the old concept of a preferred state of rest?

The idea behind Special Relativity is that there are no preferred frames. Everybody observes different results when measuring stuff and they're all correct according to their own point of view (frame of reference)

[StringJunky]

11 minutes ago, Strange said:

But it is the fact that the speed of light is invariant that allows special relativity to solve create all sorts of problems by making measurements of space and time relative.

[Simplico]

Frames of reference are an invented concept.

[StringJunky]

4 minutes ago, Simplico said:

Frames of reference are an invented concept.

It's a confirmed concept; https://en.wikipedia.org/wiki/Hafele–Keating_experiment

[Strange]

19 minutes ago, Simplico said:

'He who defends everything defends nothing'. If everyone has their own measure of space and time, does anyone have a measure of anything? 

Well, yes. They all have their own measurements, but they also know how to convert between them. So it is like an American using feet and inches (or Fahrenheit) and the rest of the world using real units. The numbers are different but we can still communicate.

10 minutes ago, Simplico said:

Frames of reference are an invented concept.

So are all measurements. Invented to describe the way the world works.

Is this going to be yet another "I don't like/understand relativity so it must be wrong" thread? 

[studiot]

40 minutes ago, Simplico said:

the old concept of a preferred state of rest?

 

Whose old concept would that be?

Please provide a reference.

[swansont]

3 hours ago, Simplico said:

I am I being stupid, or does special relativity simply substitute the concept of a preferred state of velocity (the speed of light) for the old concept of a preferred state of rest?

There is no old preferred state of rest. It was rest or constant velocity that was the preferred state, and it requires a force to change it. These are already relative frames of reference.

[Eise]

7 hours ago, Simplico said:

Frames of reference are an invented concept.

No concept is 'nature-given', so one could say every concept is invented. Science is the 'art of inventing the right concepts'. 'Right concepts' are concepts that subsume as much as possible phenomena under a theoretical umbrella, and enable us to predict results, given a set of initial conditions, simply said, that show that they work.

And be assured: special relativity is shown to work. Not just in experimental tests, but it is daily used in our technology (CERN could not smash protons at each other if the calculations for the accelerator were wrong; GPS would not work if it would not account for relativity, etc etc). It explains some phenomena we would otherwise not be able to, e.g. the colour of gold, or the relationship between electrical and magnetic fields.

So the invention of the concept of reference frame turns out to be very useful: it explains a lot!

[studiot]

2 hours ago, Eise said:

No concept is 'nature-given',

But the self referential frame of a particle is oftern called 'the natural frame.'

[Eise]

1 hour ago, studiot said:

But the self referential frame of a particle is oftern called 'the natural frame.'

You are very precise in your expression: you use the word 'called'.

I think the real question would be: did we observe nature and discovered 'natural frames', or did we create the concept, because we find that the laws of nature have their simplest form in such a frame? (I assume you mean with 'self referential frame' the frame of reference in which the object of interest is at rest.)

I am inclined to say that when a concept only has a clear meaning in the context of a scientific theory, then it is an 'invented' concept. And with 'inertial frames' I would even go farther: they do not exist at all. They are (very) useful abstractions: they make talking about relativistic effects much simpler. But I assume one could explain relativity and do not use that concept at all. 

So what I am saying to Simplicio is: yes it is an invented concept, and it has turned out that this concept helps an awfully lot to understand relativity. To use the formulation I used elsewhere: Simplicio's argument is true, but it is irrelevant. He obviously doesn't see that in science it is essential to invent new concepts.

[studiot]

But everything is at rest, relative to itself.

So no substitution has occurred.

[swansont]

23 minutes ago, Eise said:

 I am inclined to say that when a concept only has a clear meaning in the context of a scientific theory, then it is an 'invented' concept. And with 'inertial frames' I would even go farther: they do not exist at all. They are (very) useful abstractions: they make talking about relativistic effects much simpler. But I assume one could explain relativity and do not use that concept at all. 

It may be easier to see this in Newtonian physics. In an inertial frame, F=ma. In other frames, you have to add pseudo-forces to explain motion.

[Simplico]

The concept of the earth being flat is very useful for measuring or calculating short distances. It just doesn't represent reality.

[studiot]

18 hours ago, studiot said:

 

Whose old concept would that be?

Please provide a reference.

 

Along with another member, I asked a question about your assertion.

 

Please address it.

[J.C.MacSwell]

I think a local Earth frame would seem pretty natural to any species that evolved on Earth to the point they could conceptualize what a frame might be, as they would have been wired to use it for quite some time prior.

[Strange]

46 minutes ago, Simplico said:

The concept of the earth being flat is very useful for measuring or calculating short distances. It just doesn't represent reality.

Well, duh.

Was there any point to that rather obvious statement?

As you are not interested in a discussion, just posting cryptic and increasingly irrelevant comments, I am going to suggest that this thread is closed.

Edited May 24, 2018 by Strange

[swansont]

1 hour ago, Simplico said:

The concept of the earth being flat is very useful for measuring or calculating short distances. It just doesn't represent reality.

What does that have to do with the discussion?

[Phi for All]

!

Moderator Note

This discussion isn't going well. The OP needs to respond to some of the direct questions that have been posed, hopefully with some mainstream science involved.

 

[Simplico]

Ok, the concept of a preferred state of rest as told in the bible, by Aristotle, and everyone else up to Galileo (with the possible exception of Zeno).

[Strange]

14 minutes ago, Simplico said:

Ok, the concept of a preferred state of rest as told in the bible, by Aristotle, and everyone else up to Galileo (with the possible exception of Zeno).

OK. So you are talking about geocentrism. That was not as universally accepted as you suggest. For example Aristarchus, in the 3rd century BC, suggested that the Earth went round the Sun. It was Copernicus, not Galileo, who came up with the modern heliocentric model.

But what does this have to do with the theory of relativity? 

[swansont]

31 minutes ago, Simplico said:

Ok, the concept of a preferred state of rest as told in the bible, by Aristotle, and everyone else up to Galileo (with the possible exception of Zeno).

There's no mainstream science here. It's religion and philosophy.

What happened to it? Science happened, that's what.

[beecee]

1 hour ago, Simplico said:

Ok, the concept of a preferred state of rest as told in the bible, by Aristotle, and everyone else up to Galileo (with the possible exception of Zeno).

Now why the hell would you raise a book based on ancient myths, written by obscure men in an obscure age, when we are discussing the facts and logic of SR?