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Physics, Astronomy & Cosmology / Science and information theory

« on: 04/04/2022 19:40:39 »

I've recently been trying to have a discussion about the relevance of information, and what exactly is information, at another site.
It didn't really get anywhere and I found myself up against some rather fixed views. Science is meant to be about enquiry, I thought. So why are so many people not willing to examine their own beliefs and ideas, why is there so much fear about examining the possibiity that you don't "really" understand something and might need to adjust those beliefs?

But to the topic: I mentioned Landauer's principle, what it says and tried to examine whether it does pertain to erasure of information.

Well, one person who is a moderator tried to convince me that information isn't physical, so erasing it doesn't make any sense. He also appeared to believe that thoughts aren't physical, although strangely, the process of thinking, or conceiving is physical. I think that's really confused and not particularly enlightening.

So is information physical? Does the question come down to is information a pattern and can a pattern be non-physical? Moreover, is Landauer's principle true? I know it's generally accepted as true, but is that because computers are also heat engines, or are they?

Or take a look at the science of astronomy: is it just an information-gathering disciplne? how is the information gathered physically; what do humans do with this information?
How does the theory that information is not physical, fit into it?

Another question I have is, can information be characterised without the notion of a sender, a receiver, and a communications channel for transmission of signals?

22

General Science / Musings on Newton

« on: 14/02/2022 20:34:53 »

If Isaac Newton could do it, why not you?

The story goes, Newton was living in the countryside, avoiding the outbreak of the London plague, and was sitting in an orchard.

Nowadays, a high school student can "do the math" that predicts what an apple will do when it falls from a tree.
Once it is free to fall in a gravitational field, it accelerates at g, this has a local value and the planet has an average g, which differs (is differential) over the surface.

According to Mach's principle (who came along a bit later than the 17th century), the local value of g depends on all the interactions between an inert mass, and all the mass along any line from the COM of the massive object.

Which means, although  you have the "sense" of gravity having a pull in one direction, all the mass around you, in any mountains etc, is pulling at the same strength (given by Newton's constant which is very small).

You feel, therefore, a product of all this, centred in the middle of the earth and say "gravity is a central force". This force is an idea, it's an analytical idea. The force is also a product, over all the small chunks of matter in your vicinity (i.e. the planet earth, mostly), which you find the centre of, it's all directed vertically, but if you went lower into the well, any analytical "force lines" would get closer together because of the geometry: gravity is geometrical.

In fact Einstein showed that gravity is the geometry of spacetime. Newton showed that you can take a flat section of spacetime and draw a curve that follows "acceleration" for a falling object. Einstein showed that it isn't really flat, except locally where apples fall in straight lines, and see the same "sum over little bits of matter", distributed around them.

Forces are first order approximations (analytically) connected to the curvature in four dimensions; an approximation of the geometrical distribution (of a matter-field).

Now, I have a friend who, quite some years ago was enrolled in a graduate degree in mathematical physics. I went to the same uni, but wasn't studying math except for calculus, I wanted to study electronics and communications theory.

Anyhoo, he still hasn't finished the thesis so still isn't a postgrad. But his thesis is a review of Mach's principle, and I honestly can't tell you what it's about because it's all tensor calculus. But I sorta got something about a spinning bucket filled with water, and all the mass in the universe around it; i.e. in its local frame. So if the bucket is in space, in a "field-free" free region, what happens? I might be contracting a few things there (yuk yuk).

23

General Science / Superfluids

« on: 10/02/2022 01:18:46 »

Superfluid Helium in a glass container, suspended above a larger volume of the same liquid, flows up the sides, forms drops which fall into the larger volume and slowly empties.

Obviously gravity is involved and the liquid has inertia. It looks like it wants to get to a lower gravitational potential.
Does anyone know how to explain the inertia of a superfluid?