Hacker News Reader

Comment by sls | Hacker News Reader

you say:

> regarding physical models, you are assuming there is a universal truth or reality that is the same for everyone

which is basically an axiom one must adopt to engage in science. E.g., here's the formulation found in the Wikipedia article "Philosophy of Science"[1]:

> that there is an objective reality shared by all rational observers

So if one wishes to engage in an inquiry that doesn't hold this axiom, it's of course a perfectly fine thing to do, but it's best for all concerned not to call it science or scientific. Many issues and lines of inquiry that are important to people aren't amenable to scientific inquiry, but it does nothing but harm to dissimulate.

[1] https://en.wikipedia.org/wiki/Philosophy_of_science#Naturali...

View on HN

Physics already acknowledges that there is no universal truth. Maybe not with those words.

All physical models depend on a "frame of reference". The most common one being the inertial frame of reference.

They do that because it all depends on how and from where you look at something, which is just another way of saying that the models depend on an observer.

Alternatively you could interpret that as there actually being some sort of universal truth, but then the experience of it is different for every single observer.

And then again, you are the one picking an interpretation or belief over another.

The universal truth, in that case, is described by relativity. Different reference frames don't imply that the laws of physics differ between frames - in fact it's a fundamental axiom of special relativity that the laws of physics and speed of light are invariant (remain the same in all reference frames[0].)

[0]https://en.wikipedia.org/wiki/Special_relativity

The terminology as understood in physics is not the same terminology that you're using.

The term "frame of reference" refers to how you have to set up the equations and how you define values, for example physical coordinates of a location. It doesn't change the actual predictions of the evolution of a physical system (and if it did, that's generally a good sign that the model is missing something!).

For example, you can model gravity in Newtonian mechanics on the surface of Earth as a force that pulls all objects down at a constant 9.8m/s^2 acceleration. Or you can step off the planet, and model the entire Earth as a closed gravitational system, and measure the gravitational attraction between the mass of the Earth and the things on or near its surface using F=G * m_e * m / r_e^2.

When you get to relativity, you discover that the problem is that spacetime is defined in such a way that there is no well-defined global "ruler" or "clock" that applies independently to all observers, so that 1 meter or 1 second for me on Earth is not the same 1 meter or 1 second on a spaceship travelling at 0.2c. What is independent to all observers is the speed of light in a vacuum, and from these two facts, you can in fact derive how to map the definitions of how your rulers and clocks would be distorted if you moved to a different reference frame.

Reply on news.ycombinator.com