premjan

First a nice poem about neutrinos.

The theory of quantum mechanics basically looks at "combinatorial" properties of the ultrasmall world: i.e. stuff that does not behave like a fluid but tends to behave more like a particle or otherwise undergoes discrete jumps of some sort. The probabilities underlying these discrete shifts in energy, existence, spin etc. vary continuously some of the time and apparently discretely some of the time. Apparently there is evidence that neutrinos spontaneously shift flavor between three different kinds (evidence in the solar wind).http://www.lbl.gov/Science-Articles/...SNO-Lesko.html Since neutrinos have a very small mass (probably in the range of 1 electron volt) this is nearly a continous interaction, no point berating the "quantum" bit here.

Is there evidence that reality blends smoothly from the discrete quantum level down into an essentially continuous universe (populated perhaps by strings)?

Schneibster

Cute poem, I like Updike. Yes, it was called the "ultraviolet catastrophe." Max Planck proposed quantum theory to account for this behavior, and in over 120 years, no one has explained it any other way.

Another nice one is called the "photoelectric effect." Einstein won his Nobel Prize for that one.

As far as a continuous universe, otherwise known as the "continuum postulate" of special relativity, there not only is no evidence to support it, but there is a major theory that opposes it: string theory. However, by quantizing space and time in the manner prescribed by string theory, we eliminate not only the singularities from relativity, we also eliminate them from the second quantization of gravity.

premjan

I see, I remember studying that, apparently a blackbody would radiate infinite amounts of energy if energy itself were not quantized since the energy radiated goes like the square of the frequency. I need to think about why exactly quantization eliminates that. Is that because the relation itself changes for higher frequencies? I guess so.

The photoelectric effect indicates that light can interact with matter (e.g. free electrons) only in discrete packets. Does this mean that light is fundamentally quantized or that only when it hits something it is absorbed in quantum multiples? In other words, is quantization of light a property of matter or a property of light? I guess the latter, but the photoelectric effect on its own does not show that.

OK so most physicists lean towards a fundamental quantization of matter-energy into strings. This does not appear to constrain space-time to be quantized however. Is that fair to say?

Friar Bellows

A theory for which there is also no evidence.

Anglican

I think there seems to be a major misconception that all operators representing quantum mechanical observables have discrete eigenvalues, this is far from the truth. Just cos it's quantum mechanics doesn't mean that everything's quantized! In string theory too spcae and time are continious.

premjan

OK, so the existence of smaller and smaller particles (such as the neutrino) might indicate that the quantum aspect is finally somewhat restricted in utility and stuff is just continuous underneath.

Anglican

What I mean is that quantum mechnaics doesn't requie everything to be quantized, so time and postion are still contionus variables, even energy, depending on the situation, is a continous variable.

premjan

is there a possibility for particle-waves with wave-like distributions (i.e. the wave function is like an infinite standing wave, not a pulse)? This would be nonlocalized of course, in a totally different sense than the EPR paradox. Would this just be a "wave" of some sort?

Thundun

I'm not sure i know exactly what you are asking, but doesn't the particle in a box fit this description of a standing wave exactly?

Thundun

Well, to be fair, there is a little evidence against string physics

Maybe branes will pose more promise.