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New Theories / Re: what is temperature?

« Last post by hamdani yusuf on Today at 13:49:45 »

You can indeed heat things by shaking them. If the gas or liquid has nonzero viscosity, some of the kinetic energy of shaking the walls is transferred to the fluid. Friction heating of a solid is the same thing - we routinely use ultrasonic welding for plastics.

Is the vibration classified as thermal energy?

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Chemistry / Re: Shrink ray or growth ray, how could they work?

« Last post by Eternal Student on Today at 13:31:53 »

Hi.

but the volume occupied by the constituents of an atom is filled by vacuum 0, not d.

    I agree that it would be nice to change nature's   ε₀  for the universe in some local region around the person.   However, that's not something we can easily do and engineers hate it when you ask them to do the impossible.

     What we have a real opportunity to do, is to change the di-electric or pactical ε in the environment around the atoms.
     In the hydrogenic model of semiconductors, it seems that the radius of space occupied by the electron from a donor impurity does behave as if the di-electric ε of the bulk material is being used instead of nature's vaccum  ε₀.  (and also, the efective mass of the electron rather than its natural rest mass).   We've had discussions about this before (nearly a year ago):
    https://www.thenakedscientists.com/forum/index.php?topic=86760.msg722228#msg722228

   Sadly one of the links I gave to a Glasgow university website seems to be down (things change in a year).   Here's a snippet of a lecture course (Solidstate Physics) from the University of Nottingham, United Kingdom that briefly describes how the usual Schrodinger QM model of a Hydrogen atom is modified - just so you know that there really is some precedent here.    Donor impurity atoms do seem to behave as if they're bigger and it is exactly as if the dielectric ε and the effective mass of the electron in the bulk material is being used in the QM model of an atom.

Best Wishes.


     

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New Theories / Re: Where does quantization of energy of electromagnetic radiation come from?

« Last post by paul cotter on Today at 12:03:44 »

I would argue that all em is quantised but I have zero proof. A thought experiment: set up a standard black body radiator, ie small aperture in a spherical matt black furnace, and use the radiation to illuminate a photoelectric cell. As we increase the furnace temperature we see a smooth increase in frequency of the emitted radiation exactly the same as one would see if the frequency of a radio transmitter was swept up or down. The photocell however will only react when a specific frequency is reached, indicating quantisation. It may be the case that we simply do not have a suitable phenomenon to detect the quantisation of lower em frequencies, akin to the photoelectric cell for the higher frequencies.

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Physics, Astronomy & Cosmology / Re: What is the exact cause of the time dilation of the twin?

« Last post by paul cotter on Today at 11:33:53 »

"I was hoping we could lean towards what an exact reason for the different ages of the twins is". Am I missing something? I was of the opinion that this question was comprehensively answered at an early stage in this query. Surely 1/√1-vsq/csq is all one needs to answer this without digressing into ever more complicated reasoning.

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Question of the Week / Re: QotW - 24.12.12 - Is there any way to harness nuclear energy other than steam?

« Last post by alancalverd on Today at 10:14:15 »

The trick with a beta energy source is charge separation. Consider a metallic beta source surrounded by a conducting sphere with an air gap. Even at 500 keV, beta radiation is mostly absorbed in a few millimeters of copper, so you now have a self-charging capacitor C. V = Q/C, so the available voltage between the source and the absorber can be anything from zero to 500 kV depending on the ratio of beta activity to current drain.

This technique has the advantage over plutonium thermoelectric generators that it doesn't need a cold sink. PuTEGS work OK in space where you can radiate heat to the 3K background, or in the human body where you have 70 - 100  kg of water at a constant  310K, but if you want the simplest possible source of, say, 100 volts, with a wide range of operating ambient you might consider a beta capacitor.

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New Theories / Re: How close are we from building a virtual universe?

« Last post by alancalverd on Today at 09:55:52 »

How do you define bad people?

Those whose actions harm others.

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Chemistry / Re: Shrink ray or growth ray, how could they work?

« Last post by alancalverd on Today at 09:51:36 »

Problem is that you can't alter ε₀ as it is a quantity derived from observation. You can immerse your subject in  a dielectric d with a different value of ε_d but the volume occupied by the constituents of an atom is filled by vacuum 0, not d.

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New Theories / Re: Where does quantization of energy of electromagnetic radiation come from?

« Last post by alancalverd on Today at 09:42:39 »

The question here is "where does quantisation of the energy  of emr come from". If you accept that it is possible to generate emr of any arbitrary frequency, then it is clear that the energy is not necessarily quantised and the answer is that in many but not all cases it is generated by a quantum process.

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New Theories / Re: Where does quantization of energy of electromagnetic radiation come from?

« Last post by hamdani yusuf on Today at 09:38:33 »

It's quantized by the number of electrons you made to follow that path. You can't half it down.

The frequency of the emr is not quantised. I can give it any value I choose.

Did anyone told you otherwise?

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Physics, Astronomy & Cosmology / Re: Will AI really replace supercomputers for weather-forecasting?

« Last post by alancalverd on Today at 09:38:09 »

A colleague was involved in the design and construction of North Sea oil platforms. A crucial input to the building and location program was forecasting daily wave height. The Met Office forecasts were "polished" by local fishing skippers looking at satellite  images, and their accuracy improved from "just useable" to "reliable".

When the ab-inito analytic solution gets complicated, there's a lot to be said for neural processing and learning by experience.