1

Physics, Astronomy & Cosmology / Re: Does light have mass?

« on: 03/05/2020 12:04:35 »

Again, since the m here refers to proper mass, it doesn't apply to a photon.  Instead, the momentum for a photon is found by
p = hf/c
And the general equation ends up giving you E= hf for the photon.

I understand both equations (surprise!), but am not clear as to how p = hf/c becomes E= hf.

Energy is momentum times velocity. Here it is pc. Since hf/c times c cancels out the speed of light you are left with E = hf.

2

General Science / Re: When do YOU die in a many worlds interpretation?

« on: 08/12/2019 12:56:21 »

The problems begin when people try to add philosophy to quantum mechanics. They feel shocked that the results of experiments seem weird. They don't fit with their rational world view. That is not a shortcoming of quantum mechanics. It is a result of our limited perspective.

It isn't a problem that quantum mechanics is counter intuitive. It is the most interesting aspect of it.

3

General Science / Re: When do YOU die in a many worlds interpretation?

« on: 07/12/2019 12:38:15 »

You die. If you are buried then other lifeforms feed on you. They consume your energy for their own use. If you are cremated all your energy goes up a chimney. This continuous cycle continues until all species become extinct, the planet loses its atmosphere and water. Then the sun expands to consume the planet. Ultimately many worlds are consumed this way until the ultimate heat death of the universe. And they all lived happily ever after.

4

Physics, Astronomy & Cosmology / Re: Does information have mass?

« on: 08/11/2019 19:50:30 »

The sky is blue. That is information about the sky. Does it have mass? No, it is descriptive. The photons have energy, which has an equivalent relativistic mass. Define your interpretation of information.

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Physics, Astronomy & Cosmology / Re: What happens when both slits are observed by in the double slit experiment?

« on: 07/11/2019 21:40:57 »

Relativity is a classical and deterministic theory. Quantum mechanics introduces probability, which is not deterministic.

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Physics, Astronomy & Cosmology / Re: Does information have mass?

« on: 07/11/2019 21:20:31 »

Define your interpretation of information.

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Physics, Astronomy & Cosmology / Re: What happens when both slits are observed by in the double slit experiment?

« on: 06/11/2019 23:32:06 »

Also worth viewing

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Physics, Astronomy & Cosmology / Re: What happens when both slits are observed by in the double slit experiment?

« on: 06/11/2019 23:19:07 »

@Lloyd Quantum mechanics is just weird. That's the way it is. Probability is the key. It wasn't chosen to be that way by physicists. Look into polarised light and filters.
https://www.khanacademy.org/science/physics/light-waves/introduction-to-light-waves/v/polarization-of-light-linear-and-circular

This is where we eventually get to Bell's inequality. Go read up on it!

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Physics, Astronomy & Cosmology / Re: What is the energy of a red-shifted photon?

« on: 04/08/2019 09:35:37 »

Where does the energy go, (approximately) inertial version. Say you are standing still and a bowler throws a cricket ball at you. It hurts! Now say you are riding a moped past the bowler and he throws the cricket ball at you. Since you are almost matching the speed of the ball it hurts a lot less. So where did the energy go? It was relative to the velocity of the victim and the bowler.

10

Physics, Astronomy & Cosmology / How well do laymen understand Bell's theorem?

« on: 03/08/2019 12:20:17 »

I just watched this video

. It may well help others to understand better. It is a difficult concept to grasp. Let me know if it helped.

11

Physics, Astronomy & Cosmology / Re: Does this equation mean anything?

« on: 18/07/2019 22:32:37 »

Has anyone done the dimensional analysis? 

12

Geology, Palaeontology & Archaeology / Re: SPAM.COM

« on: 18/07/2019 16:30:43 »

Well this user's particular machine is in Clifton, New Jersey. It may well be a compromised PC in a botnet.

13

New Theories / Re: Are all photons mediated in the same way through the quantum vacuum

« on: 16/07/2019 00:01:52 »

Now some food for thought. From here https://www.physicsforums.com/insights/misconceptions-virtual-particles/

"States involving virtual particles cannot be created since quantum field theory has creation operators only for observable particles whose 4-momentum satisfies the mass-shell constraint. For lack of a state, virtual particles have none of the usual physical characteristics of real particles: They cannot be said to exist in space and time, have no position, no meaningful probabilities to be created or destroyed anywhere, no life-time, cannot cause anything, interact with anything or affect anything. Therefore there is also no dynamics, speed of motion, or world lines. (In physics, dynamics is always tied to states and an equation of motion. Neither exists for virtual particles.)"

That sums it up in a nutshell, or off-shell if you prefer. If you wish to argue otherwise feel free to but in new theories.

14

The Environment / Re: How much effect does water vapour have as a proportion of global warming ?

« on: 08/07/2019 23:09:35 »

Maybe it's the fact that once again, the democtatic system fails by popular consensus overriding the the sane conclusion, majority decision on the side of the wrong tangent.

You appear to be arguing just for the sake of it. Taking up an opposite position to prolong a confrontation. I don't see what benefit you are getting from it

15

New Theories / Re: New Theories: Will all moving objects with mass generate gravitational waves?

« on: 23/06/2019 18:33:20 »

All points in a gravitational field have a gravitational potential associated with them. This is not energy and the units for this potential are J/kg (joules per kilogram). The unit for energy is just the Joule. This is the same as the unit for work.

So the potential represents the amount of work required to get an object to a particular point in the gravitational field. This is why it is stated that an object gains potential energy by being moved to the point in the field. That is raised off the ground for instance.

This is an important distinction to remember .

16

New Theories / Re: New Theories: Will all moving objects with mass generate gravitational waves?

« on: 20/06/2019 10:26:50 »

It has to be remembered that acceleration can be a change in speed, a change in direction or both. Both orbital and radial free fall cause acceleration and yet within a falling frame you would detect no gravitational radiation

17

New Theories / Re: Can a photon be visualized ?

« on: 07/04/2019 14:51:54 »

To describe observations the mathematics also has to be able to make predictions. These then can be tested and shown to agree with new observations or not. If a certain constant is required to produce those mathematics then it is used. There is no intention to explain why it is needed. It just works. How would you answer the why? How can anyone observe a vacuum?

18

Plant Sciences, Zoology & Evolution / Re: If I tied a magnet to a pigeons head , would it fly in circles ?

« on: 03/03/2019 14:37:36 »

The experiment has been performed. It does have a disorienting affect. Please see for instance https://www.researchgate.net/publication/17893396_Magnets_Interfere_with_Pigeon_Homing/amp

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Physics, Astronomy & Cosmology / Re: Does time stand still in the quantum world?

« on: 03/01/2019 22:42:58 »

If anyone has used a stopwatch they are aware of time as a measurement of change.

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Physics, Astronomy & Cosmology / Re: Does time stand still in the quantum world?

« on: 03/01/2019 21:34:16 »

I like a good debate but the concept of time seems to be flogged to death for no reason. It is simply a mechanical means of measurement of change in one form or another. The fact that those mechanics don't always run at the same pace in different frames is not that difficult.