1

New Theories / Re: Density Wave - Is it real?

« on: Yesterday at 21:53:45 »

72 present of the galaxies that we observe are spiral

You seem to imply that these are flat galaxies that don't show a spiral structure.

That's because there are many other types of galaxies that aren't flat:
- Elliptical galaxies are formed by the collision of two or more galaxies, which disrupts any spiral pattern, and consumes most of the dust (so new arms can't form). This will happen to Milky Way + Andromeda = "Milkomeda"
- Dwarf galaxies/irregular galaxies/globular clusters : Their arms have been distorted and ripped off by interactions with a larger galaxy, leaving no record of spiral arms (if any)

See: https://en.wikipedia.org/wiki/Galaxy#Types_and_morphology

Total Speculation: We now know that most galaxies have a central black hole.
- We know that there are relativistic jets produced from the accretion disk around this black hole
- Sometimes there are 2 or more central black holes, remnants of previous galactic mergers
- We expect that  the axis of the central jets will change when central black holes merge (and there are examples of this in radiotelescope images)
- So what if a black hole merger produces a jet whose axis intersects the disk of the galaxy?
- Won't that set off linear changes in the disk (eg a barred spiral)?

Of course, a relativistic jet might not be comfortable for life in the spotlight...

Please Discuss...

2

Physics, Astronomy & Cosmology / Re: where does permanent magnet energy come from

« on: Yesterday at 20:58:03 »

where does permanent magnet energy come from...If I push the top magnet towards the lower one

You just answered the question.

Pushing the top magnet down against the repulsion of the lower magnet requires a force F.
This is applied over a distance s.
The product of Force an distance = Energy: Fs=E

This is just the same as if you had compressed a spring and released it.

if the bottom magnet was replaced with an electromagnet then electrical energy would be required to support the top magnet

Not if the electromagnet were superconducting; this will maintain a magnetic field for as long as you keep it cool.

A conventional copper electromagnet continually loses energy through resistance, and this loss must be overcome to maintain  the magnetic field.

where does permanent magnet energy come from

Another way of looking at this question is that the "natural" state of the magnet's alloy has a very low external magnetic field (comparable to the Earth's magnetic field). So the same metal with a powerful magnetic field appears to be in a "higher energy" state.

This magnetization is imposed during magnet manufacture, by cooling it below the Curie temperature in the presence of a powerful external magnetic field.

But if you expose the magnet to environmental abuse: hitting it with a hammer, increasing its temperature near the Curie temperature, etc, then entropy means that the aligned magnetic domains will realign, and return to the inert state, matching Earth's weak magnetic field.

This is an effect of entropy - objects tend to return to a lower energy state.

Oops! Overlap with Bored Chemist...

3

New Theories / Re: Coronavirus will get weaker and then what?

« on: 01/12/2021 09:42:58 »

Omikron variant. It gives:
- headaches
- caugh
...and nothing more.

How do you know? This variant has only been studied for a few weeks.
- It has been studied in a mostly young population. What happens when it gets into an aged-care facility near you? Nobody knows.
- It took several months for Long COVID to be recognized as a syndrome. It won't be obvious yet if this variant produces less (or more) long COVID.

We won't be able to make confident assertions about this variant for a few more weeks - maybe a month (and academic papers will continue being published for a few years...). In the meantime, we have to rely on anecdotal evidence:
- Symptoms did seem milder (to one doctor): Promising that it might be less virulent/lethal
- Loss of smell was not so common: Promising that it may cause less nerve/brain damage
- It did seem to overtake Delta in one province: Concern that it may be more transmissible.

4

COVID-19 / Re: Covid-19, High infection rates why no new variants being reported

« on: 30/11/2021 08:39:46 »

will be interesting to see the effect on vulnerable patients

I heard that African countries don't tend to have as many elderly people as "Western" countries (as a % of population).
That may make it hard to extrapolate to those elderly people who have been the majority of COVID victims to date in Western countries.

5

COVID-19 / Re: Covid-19, High infection rates why no new variants being reported

« on: 29/11/2021 21:11:16 »

One of the doctors treating Omicron patients in Africa said that symptoms were different from Delta, and  "infected do not suffer the loss of taste or smell"
In Delta, about 40% of infected people lose their sense of smell (which impacts taste).
If proven, that would be promising. Nerve-supporting cells (astrocytes and microglia) are susceptible to COVID infection as they express the ACE2 receptor; death of these cells is suspected of causing the loss of smell nerves.

These astrocytes and microglia cells also exist in the brain, and death of neurons in the brain is thought to cause the "brain fog" reported by many victims of long-COVID.

Neurons in the nose regenerate after damage; most neurons in the brain do not regenerate. A study of people recovered from COVID infection showed a faster-than-normal loss of brain tissue.

6

Physics, Astronomy & Cosmology / Re: M87 black hole's image is of 55 million years ago

« on: 29/11/2021 21:06:59 »

Astronomers always look back in time. The bigger the telescope, the farther back in time they can look - which is why astronomers are holding their breath for the launch of the James Webb Space telescope, currently scheduled for end-2021.

We can see that M87 is very active in the light reaching us now. It is possible that the center of M87 had been disrupted by some event (like the merging of two black holes) that sent many stars plunging into the accretion disk. It is possible that it is quieter now, or more active now - we really can't know.

The black hole at the center of the Milky Way is much closer - about 25,000 light years. From the light reaching us now, it looks fairly quiet. But there is evidence that it was much more active in the past, judging by vast clouds of gas above and below the Milky Way galaxy, presumably put there by intense jets of gas from a more active period of the black hole at the center of our galaxy. It is likely that it will activate again, if a large star falls into the accretion disk.
See: https://fermi.gsfc.nasa.gov/science/constellations/pages/bubbles.html

7

Just Chat! / Re: What does it mean to dream about travel?

« on: 29/11/2021 02:24:06 »

I dreamed of travel to a warmer destination, about 1,000 km closer to the equator.

Our goal was only achieved the 4th time we booked, due to pesky COVID cancellations...

8

COVID-19 / Re: Covid-19, High infection rates why no new variants being reported

« on: 28/11/2021 10:20:48 »

omicron 5

I assume that is a geeky reference to Star Wars?

A week ago, that would have been an easy find on Google. This week, any mention of 'omicron' brings up stories about COVID variants...
See: https://starwars.fandom.com/wiki/Omicron_5

9

General Science / Re: mass and entropy

« on: 28/11/2021 10:16:41 »

the Earth...entropy.

Entropy increases in an isolated system.

However, the Earth is not an isolated system:
- On one side, the Sun pours in about 700 Watts per square meter
- On the other side, heat radiates about 700 Watts per square meter into black space
- In between, Earth's biosphere makes use of this huge energy flow to survive and even thrive

It's a pity that one part of the biosphere (humanity) seems intent on taking over many other parts of the biosphere...
- This is losing a lot of genetic diversity (ie DNA variants which you could describe as "information")
- Loss of information is another description of increasing entropy

10

COVID-19 / Re: Covid-19, High infection rates why no new variants being reported

« on: 27/11/2021 10:22:20 »

B.1.1.529 is now officially dubbed "Omicron", Greek letter "ο".

They skipped 2 Greek letters; some claim the reasons are:
- Nu "ν" because it could be confused as a "New Variant" instead of "ν Variant" (by English speakers)
- Xi "χ", because it is the name of the Chinese head of state

11

Just Chat! / Re: Does boredom play a role in obesity?

« on: 27/11/2021 10:12:47 »

Yes.

The same could be said for watching streaming video, gardening, and (less often) going to work.

12

Physics, Astronomy & Cosmology / Re: Cosmic inflation, before or after the big bang?

« on: 26/11/2021 21:28:40 »

Cosmic inflation, before or after the big bang?

Most of the discussion seems to be centered on the Big Bang as a point in time, which can be compared to other points in time.

However, more generally, the Big Bang Theory is about the process which led to the universe as we see it today, which includes various phases such as Cosmic Inflation, production of subatomic particles and production of the current Cosmic Microwave Background Radiation (which took about 400,000 years). Somewhere in there is the mysterious process that gave us more matter than antimatter...
See: https://en.wikipedia.org/wiki/Big_Bang

if physics breaks down at 10^-43 sec, how do they figure that number?

That is when it is predicted that energy levels would have dropped enough so that the 4 forces that we know would have become distinct fields.
- As I understand it, there is theory of how the Electromagnetic & Weak nuclear force would have behaved as a combined entity. https://en.wikipedia.org/wiki/Electroweak_interaction
- But we still don't have a quantum theory of gravity, and gravity would have had a major impact in this environment.
See: https://en.wikipedia.org/wiki/Big_Bang#Inflation_and_baryogenesis

13

COVID-19 / Re: Covid-19, High infection rates why no new variants being reported

« on: 26/11/2021 07:23:28 »

why no new variants being reported

There are new variants arising continually - every chain of infection has a mutation about every 2 weeks, and there are hundreds of thousands of chains of infection.
- However, most of these variants are less infectious than Delta, and so they don't spread very far.
- There is an active network of researchers looking for new variants that seem more transmissible, or more lethal, or which might evade immunity (whether natural or vaccine-induced)

A new variant has arisen in South Africa which seems to be more transmissible than Delta, and WHO is holding a conference to review what is known about it.
- If they consider it a "Variant of Concern", they will give it a Greek letter, instead of the current B.1.1.529
- It does have a lot of mutations, including about 30 in the spike protein alone, which makes it a risk for evading immunity.
- Some countries have blocked flights from Southern Africa, to reduce the chance of it entering their country

See, for example: https://www.nature.com/articles/d41586-021-03552-w

14

Physiology & Medicine / Re: Could hitting a punch-bag cause abdominal pain?

« on: 25/11/2021 20:33:35 »

The hospital doctor has proscribed 2 buscopan tablets 4 times a day

A bit of pedantry:

• Prescribed: advise and authorize the use of (a medicine or treatment) for someone, especially in writing
  
• Proscribed: Forbid, denounce or condemn

15

Question of the Week / Re: QotW - 21.11.08 - Does space traffic control exist?

« on: 25/11/2021 06:32:45 »

Could the Russian missile test really have been aimed at the Elon Musk's Starlink satellite constellation?
- The target spy satellite was reportedly at an altitude of around 480km
- Starlink has a thousand satellites in orbits around 550km altitude, with more planned for 540km

Could the cloud of debris intersect the Starlink orbital planes, and gradually trash them?
Could this end Elon's plans for global telecommunications domination?
https://en.wikipedia.org/wiki/Starlink#Constellation_design_and_status

16

Question of the Week / Re: QotW - 21.11.28 - Why do ant bites hurt so much?

« on: 24/11/2021 20:37:31 »

Even without the formic acid, some ants have very large jaws, which could give you quite a nip...
While one ant may not be too bad, they have the advantage of large numbers, and some species tend to attack in swarms..
See: https://en.wikipedia.org/wiki/Army_ant

17

Physics, Astronomy & Cosmology / Re: Is it possible to recreate a black hole?

« on: 24/11/2021 20:33:10 »

Is it possible to recreate a black hole?

This question implies that a black hole previously existed, and you want to recreate it.
- Unfortunately, for stellar-mass black holes, they persist for an extremely long time.
-They evaporate via Hawking Radiation, and are expected to last about 10⁶⁴ years.
See: https://en.wikipedia.org/wiki/Hawking_radiation#Black_hole_evaporation

There is a possibility that micro-black holes could be formed in extreme energy conditions, such as the Big Bang, and these could last to today, in which case they would very tiny, and would explode in a blaze of gamma rays and subatomic particles.
- It is theoretically possible that some future super collider (far more powerful than the LHC) could create micro black holes, which would promptly evaporate. The LHC has been watching for these events, but it is regarded as a faint hope (the energies required are far too high).

18

COVID-19 / Re: Covid-19, High infection rates why no new variants being reported

« on: 24/11/2021 08:44:57 »

What control process in the viruses allow them to hijack ribosomes?

Viruses produce messenger RNA.
Ribosomes translate messenger RNA into proteins.
- The Ribosome does not check whether the mRNA came from the cell's own DNA, an invading virus, or a mRNA vaccine, but will start transcribing mRNA into proteins.
- So effectively, the virus (and mRNA vaccines) hijack the cell's protein-making machinery for their own use.

See: https://en.wikipedia.org/wiki/Ribosome

19

Physics, Astronomy & Cosmology / Re: How long does a gravitational wave last?

« on: 24/11/2021 08:38:39 »

does such a massive event only produce a wave/s capable of being observed for a very short length of time?

It takes millions of years for two black holes to merge, and they radiate gravitational waves all that time. However:
- The frequency is too low for LIGO to detect
- The power level is too low for LIGO to detect
- A proposed space-based gravitational wave detector would be able to measure much lower frequencies, and so may be able to detect hundreds of pairs, all slowly getting closer to each other, months before they move into the frequency range detectable by LIGO.
See: https://en.wikipedia.org/wiki/Laser_Interferometer_Space_Antenna

From another angle, some of the observed events are billions of light-years away. So any observers with similar equipment to ours would have been able to detect them long ago.  See the list here (1 MegaParsec=Mpc = 3.2 Million light-years).
https://en.wikipedia.org/wiki/List_of_gravitational_wave_observations

is the total  energy  level  on each concentric ring of the sphere the same no matter the distance from the source measurements are made?

If you add up the energy in each expanding sphere, it will stay the same, no matter how far you travel.
- Apart from some loss due to refraction from black holes, etc
- Which would not be much, because a stellar-mass black hole is perhaps 10km across, while the wavelength of gravitational waves is 1,000 km or more. A wave is not much affected by anything smaller than 1/4 wavelength. But a black hole in the center of a galaxy would have more of an effect on the higher-frequency gravitational waves.

always getting weaker by distance per the inverse square law.

As I understand it, our current generation of gravitational wave detectors do not measure the energy of the gravitational wave directly, but measure the strain of the spacetime distortions. The energy is proportional to the square of the strain.

This means, of all the methods used by astronomers for exploring the universe, this one does not suffer from the inverse-square law, but degrades as an inverse law.
- If you increased the area of an optical telescope by a factor of 4, you would be able to see twice as far, and explore a volume 8 times larger (inverse square law).
- If you increased the sensitivity of a gravitational wave detector by a factor of 4, you could see 4 times as far, and explore a volume 64 times larger (inverse law).

20

COVID-19 / Re: Covid-19, High infection rates why no new variants being reported

« on: 23/11/2021 09:16:57 »

No mention of a "gene which surpresses the immune system" in either article. It's poteins which which do that.

SARS-COV2 is an infectious pathogen.
- If the proteins that suppressed the interferon/immune response were just stored as proteins, they would be used up when the first cell got infected.
- In fact, these immune-suppressing proteins are coded by genes in the viral RNA
- So that as soon as the human cell gets infected, these viral proteins are churned out by the ribosomes, get into the human cell nucleus, and suppress interferon production.

The viral RNA also gets copied, packaged into new virions, which are released to infect new cells, before the human immune system catches up with the fact that it has a raging infection
- Unfortunately for some people, their immune system then goes into overdrive, attacking everything in sight (a "cytokine storm").

PS: There are some proteins that are "self-replicating", such as the prions which cause mad-cow disease, and perhaps some of the protein masses seen in some neurodegenerative diseases. But it is the viral RNA which codes for the replication of proteins in COVID-19.
See: https://en.wikipedia.org/wiki/Prion