1

Physics, Astronomy & Cosmology / Re: What would happen if every neutron on Earth disappeared?

« on: 03/06/2021 02:24:15 »

Everything would be hydrogen-1. The hydrogen gas would be drawn together by gravity and stars would be born. New neutrons would be created in these stars. And they all lived happily ever after.

2

Geek Speak / Re: Do we have enough safeguards for the advancement of science?

« on: 01/06/2021 21:05:37 »

Alan, if you don't mind me making this observation, you sound rather too politically-minded to be a proper scientist.

Science should be neutral as regards politics.  Whereas as you come across as a bit of a "Lefty".  No offence intended!

But   -   are you secretly working for the Chinese Communist Party?

Is that meant to be serious? Scientists aren't robots. They are human. Are you working for the far-right? You seem to be a bit of a "righty".

3

Geek Speak / Re: Do we have enough safeguards for the advancement of science?

« on: 31/05/2021 20:56:03 »

And the Nazis fled, mainly unscathed, around the globe. Some escapees were later brought to justice but not all. So the sociopaths and psychopaths won the day.

4

New Theories / Re: Is this the new model of the Universe?

« on: 31/05/2021 04:39:00 »

Let us have a look at the Journal Of Cosmology, that renowned periodical.

https://en.wikipedia.org/wiki/Journal_of_Cosmology

Crackpottery in the extreme.

5

Physics, Astronomy & Cosmology / Will this news modify relativity?

« on: 30/05/2021 14:23:51 »

From the BBC.

6

Physics, Astronomy & Cosmology / Re: what would happen if gravitational mass were different than inertial mass?

« on: 17/05/2021 00:30:56 »

This is also of relevance to this thread. https://en.m.wikipedia.org/wiki/Paradox_of_radiation_of_charged_particles_in_a_gravitational_field

7

New Theories / Re: Could this be what t=zero was like?

« on: 09/05/2021 13:11:57 »

As Halc points out, the entropy of the universe wasn't zero at the time of the big bang.

Here is a link to a discussion on the subject.
https://www.researchgate.net/post/What-was-the-value-of-the-entropy-of-the-Universe-shortly-after-the-Big-Bang

8

COVID-19 / Re: Are any viruses known to make a quick exit once they're rumbled?

« on: 01/05/2021 17:37:38 »

Once a virion has left the cell in which it was created it can either infect a new cell in the same host or shed to find a new host.

Virions can't fly.
They can not tell if the next cell they come across is from the same host, or from someone they got sneezed onto (or whatever).

They are not in any position to make decisions about their fate.

Set fair, the above is the most important point to absorb. Sit with a cup of coffee, tea or any other beverage you prefer and think it through. Qualified people have given up their time to give you the correct answers. You would not get this opportunity at most forums. Have a nice day.

9

Physics, Astronomy & Cosmology / Re: How do galactic jets form?

« on: 11/04/2021 22:41:28 »

Here is the link.
https://eps.leeds.ac.uk/maths-astrophysical-geophysical-fluid-dynamics/doc/relativistic-astrophysics

10

General Science / Re: Would you tell the world if you knew an asteroid was coming to Earth?

« on: 10/04/2021 15:46:38 »

Why wouldn't we just drag Bruce Willis out of bed, stick him in a rocket, and say, "Go do what you did in that film!" Then run like hell.

11

Physics, Astronomy & Cosmology / Re: Is time travel possible?

« on: 06/04/2021 06:44:32 »

The trouble with the idea of time travel to the past is, there is nothing to go back to. We invented time as a way of measuring change. You could argue that time dilation shows time is real. However, that is only a slowing down of physical processes. The slowing down of the change of states.

12

Physics, Astronomy & Cosmology / Re: Is time travel possible?

« on: 30/03/2021 22:54:06 »

Say you had a rival in business. You send an assassin back in time to kill your rivals grandfather. Now the rival is never born so you don't have the reason to send the assassin in the first place.

You have invented Schrödinger's grandfather. Alive and dead at the same time.

13

Physics, Astronomy & Cosmology / Re: How can conformal cyclic cosmology exist?

« on: 27/03/2021 10:10:36 »

Sir Roger Penrose says since mc^2 = hf clocks require mass, and his operation of squashing infinity requires it. Therefore his Conformal Cyclic Cosmology depends on it. Yet the very same mathematics says E = hf, so just energy also implies clocks. This undermines his theory.

There is a mass/energy equivalence. Also there are various types of energy. Rest energy, kinetic energy, potential energy etc etc. His theory involves the concept of the end of one universe initiating the next big bang. If the universe experiences heat death and all the black hole evaporate you have a situation where time has no meaning. Much like before the big bang. In this theory there is also no big crunch.

When you have heat death there is no more useful energy available to do work. So it is not possible to construct a clock. it doesn't matter which energy equation you cite.

14

General Science / Re: What is a black hole?

« on: 22/03/2021 10:58:54 »

One of the reasons that QM does not fit with general relativity is the information paradox. This involves the loss of quantum states. Many states can devolve into the same state. The wave equation should, in principle, be able to determine the state of a system at any point in time if the initial state is known. This is violated when things fall into the black hole. Information is no longer available to determine a systems state. This is information loss.

15

Physics, Astronomy & Cosmology / Re: Which stars by name or type emit polarised light?

« on: 21/03/2021 16:40:33 »

You mention dust in regard to this. Brian May's thesis, which has been published in book form is about dust. See https://spiral.imperial.ac.uk/handle/10044/1/1333

While this is not directly related to your post it is of interest generally.

16

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.

17

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.

18

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.

19

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.

20

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.