stupid physics questions

[pogo]

Welcome to the world of modern physics. QM is completely unintuitive to us, with our minds shaped by our experience of a universe governed by classical physics. But it's also correct: we know this as it makes many testable predictions. Not only that but many phenomena in life are only explainable by QM, and it impacts our lives much more directly than general relativity, which we mostly have to stare into space to detect.

[zip accident]

Welcome to the world of modern physics. QM is completely unintuitive to us, with our minds shaped by our experience of a universe governed by classical physics. But it's also correct: we know this as it makes many testable predictions. Not only that but many phenomena in life are only explainable by QM, and it impacts our lives much more directly than general relativity, which we mostly have to stare into space to detect.

What you are not taking into account there is that our intuition has been honed by billions of years of natural selection to deal with the world as it is, whatever that may be.

[pogo]

How am I not taking it into account? That was precisely my point: what's intuitive to us is what we perceive, and that is largely described by classical physics. We needed QM to explain things at the sub-atomic scale, which we cannot perceive directly, i.e. without special tools. The thing about sub-atomic physics is it takes place in a domain very different from the world we know. We think of things as being physical, having mass, size, strength etc. But those all arise from the properties of large numbers of atoms and the bonds between them. Sub-atomic physics concerns itself with single atoms and the things inside them. Of course it is counter-intuitive as the things out intuition relies on are absent.

[zip accident]

How am I not taking it into account?

Perhaps I misunderstood you. You seemed to me to be saying the intuition is rubbish, and we shouldn't use it any more.

The linked result is very strange.

We seem to be heading into an era of strangeness where the simpler explanation is that this is a simulation and it is being stopped and items and events inserted into it, rather than it is running continuously and consistently, or maybe even being real.

[pogo]

Classical physics is fine as a model for the physical universe at a human scale, and that's what most people find intuitive. Modern physics though incorporates two theorems, General Relativity and Quantum Mechanics, which don't conform to classical physics. So Relativity says that if you go very far, or very fast, or close to a very massive object so you have to use different rules. While QM says that at the sub-atomic scale you have to use different rules.

Thankfully though at the scale of our existence they both approximate very well to classical physics. E.g.relativity effects orbits (such as of the planet Mercury, or of GPS satellites) but the effect is small because the masses involved are small. It's only significant for GPS as it depends on very precise timing to work. QM in some ways is easier to justify as it arises far more in our modern world. Semiconductors for example depend on it, so all modern electronic devices. It's just that we didn't start making semiconductors until very recently as we didn't understand the science needed for them, including QM.

[gravy]

We seem to be heading into an era of strangeness

That era started well over a century ago.

where the simpler explanation is that this is a simulation and it is being stopped and items and events inserted into it, rather than it is running continuously and consistently, or maybe even being real.

Simple is just a quality, it has no bearing on whether it's a good explanation or not. I mean QM isn't a simple explanation but like pogo says it's an incredibly effective / accurate one.

[Absolute_Zero]

Since you [zip] seem to be in the mood for stopping the world in order to get off... you can probably also forget what I assume you probably believe to be true about the conservation of energy.

http://freelanceastrophysicist.com/2011 ... ice-versa/

[merman]

Now they're just taking the piss.

http://news.sciencemag.org/sciencenow/2 ... tml?ref=hp

Via /.

When does quantum physics come out as magic?

Any sufficiently advanced technology is indistinguishable from magic.

We know and accept gravity as a force. We don't know HOW it works. Likewise at a quantum level, we know that particles are made of quarks that cause certain behaviours and forces. But we don't know how.

[gravy]

Well.

Hadrons are made of quarks, Are they particles themselves or just collections of particles?

[Absolute_Zero]

There's no experimental suggestion (as yet) that quarks are composite, nor any standard model need. So that's a maybe.

If subcomponents do exist they'll probably be known as preons.

[gravy]

There's no experimental suggestion (as yet) that quarks are composite, nor any standard model need. So that's a maybe.

If subcomponents do exist they'll probably be known as preons.

Yeah I know, I was talking about hadrons and whether you'd call them particles or not.

[Absolute_Zero]

Yeah I know, I was talking about hadrons and whether you'd call them particles or not.

Oh, I see. I'd call those composite particles.

If non-composite, fundamental/elementary particles.

[Whiteball]

We know and accept gravity as a force.

Do we?
I'm not following this thread and certainly don't know much about the subject but just throwing this out there. I thought even Einstein said Gravity may not be a force. Didn't he think it was a curve in space time.

[merman]

We know and accept gravity as a force.

Do we?
I'm not following this thread and certainly don't know much about the subject but just throwing this out there. I thought even Einstein said Gravity may not be a force. Didn't he think it was a curve in space time.

Relativity - first proposed by Galileo - proposes that space and time are linked, and thus the movement of any body can only be measured relative to everything else. What we call gravity is the force experienced due to the curvature of spacetime - but science cannot point to anything and say THAT is WHY spacetime is curved in that way, only calculate and predict the effect.

[Dio]

Warning, two conflicting definitions of the term 'force' in play here.

Definition 1: Force, as in F=ma
Definition 2: Force, as in 'fundamental force of nature'

It is arguable that gravity, if "simply" arising from the curvature of spacetime (and not from some underlying quantum field system; there's as of yet no evidence for 'gravitons'), doesn't fall under the latter. That does not mean it can't have an existence by F=ma. In the same way that we don't need to understand the complex set of strong and electromagnetic underlying physical processes to know that snooker balls bounce off each other with highly elastic collisions.