1

General Science / Re: Are Black Holes The Blackest Things Ever ?

« on: Yesterday at 02:39:42 »

Apparently, the current record-holder for blackest materials (as of 2019) is a forest of carbon nanotubes grown on aluminium, claimed to absorb 99.995% of incoming light.
- Ultrablack materials are very useful in construction of telescopes, as they reduce those annoying lines radiating from bright stars, and other optical defects.
See: https://sitn.hms.harvard.edu/flash/2019/back-black-new-blackest-material/

But black holes are far blacker: Despite the accretion disk of a black hole getting hot enough to emit X-Rays, the event horizon of a solar-mass black hole has an effective surface temperature of around 60 nanoKelvins, due to Hawking radiation.
See: https://en.wikipedia.org/wiki/Hawking_radiation#Overview

2

Physics, Astronomy & Cosmology / Re: Why does The Sun's Polarity Change Every 11 years and Earth's is so unreliable ?

« on: Yesterday at 02:28:59 »

A magnetic field is generated by the movement of conductive fluids inside the Earth and the Sun.
- In the case of the Earth, this is liquid iron/nickel alloy in the outer core
- For the Sun, it is Hydrogen/Helium plasma in the core
- Laboratory studies have used liquid sodium, and produced magnetic field reversals on timescales that are feasible in a laboratory experiment (ie much less than years)
- As you could imagine, there is a very different viscosity and inertia (and temperature) between these different fluids
- So it is not surprising that magnetic field reversals happen on very different timescales in these different environments.

Fluid flow is often a chaotic process, as we see with the Earth's magnetic field, and laboratory studies.
- The Sun's magnetic field is not exactly a model of regularity, since sunspots virtually disappeared for 70 years during the Maunder minimum (ironically, this started not long after Galileo brought them to the attention of European scientists - the Chines had been studying them for centuries).

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

3

Physiology & Medicine / Re: Can JUST a head survive ?

« on: Yesterday at 02:13:50 »

It's already been done, on Futurama... 

4

Physics, Astronomy & Cosmology / Re: Correlation vs association

« on: 24/05/2022 23:35:29 »

a is the independent variable, b is the dependent variable

I know that this is normal terminology, but it implies a causal direction.
- If there is some variable in your experiment that you can easily control, and another variable that you can easily measure, then it is fair to say that "when I changed variable x, variable y changed in a (linear/parabolic/exponential) manner"

However, when it comes to complex things like the impact of obesity in a human population on heart attacks:
- There is no easy way to control obesity in a whole population
- There is no easy way to control heart attacks in a whole population
- There are many factors which can cause heart attacks (eg genetics, congenital problems, education on exercise, stress)
- There are many factors which can cause obesity (eg genetics, income, education on healthy diet, stress)
- So the easiest thing to do is to do some sort of scatterplot of obesity vs age of first heart attack
- Then do a regression line through it, to conclude that  "with increased variable x, variable y changes in a (linear/parabolic/exponential) manner"
- You could hypothesize that obesity contributes to heart attacks (since the obesity was present before the first heart attack), but it's not guaranteed: Someone who has an underlying heart condition may be predisposed to a sedentary lifestyle, which may make them obese.
- You could make comments like "For patients with BMI > 30, a weight reduction of 1 kg is associated with a delay of z years in age of first heart attack."

5

Just Chat! / Re: a suitable pseudonym

« on: 22/05/2022 01:03:17 »

I've never met a scientist who I would call remotely autistic.

Until around the 1980s (perhaps, until the release of Rainman, in 1988), autism was commonly seen as a development problem of infants, who were often locked up in institutions. Since virtually all scientists are adults, they could not be autistic, by definition.

Now it is recognised as:
- occurring in adults too (usually children who grew up outside an institution, and learned to adapt)
- occurring in a spectrum, from very mild to very severe
- more severe cases often being seen as children of parents with mildly autistic tendencies (ie a strong genetic contribution) - with Silicon Valley being a particularly intense hotspot

We can now look back and see scientists who were almost certainly autistic, eg
- Cavendish, who was brilliant, but could never talk directly to people, but used correspondence.
- Mendel, who spent years breeding peas
- Darwin, with his intense childhood focus on collecting bugs
- Even many of the early researchers into childhood autism! (in one case, because they had an autistic child themselves)
- It is that often-introverted focus on collecting information in some specific area, often with a numeric focus that means someone with autistic tendencies is more likely to become a scientist, engineer, musician or perhaps an artist (in contrast to movie star or a socialite, for example).
- A text-based forum like this one is likely to attract people with some of these characteristics...

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

You spend your whole life trying to find something you enjoy, and then everyone tells you to shut up about it.

6

Chemistry / Re: How well understood is the Chemistry of the trans-uranic elements?

« on: 17/05/2022 11:46:54 »

I wonder if Schrodinger's cat thought experiment needs to be re-written.

Sean Carrol is a cat-lover, and has rewritten the Schrodinger's cat thought experiment: Instead of a radioactive decay releasing a poison gas, it releases an anesthetic gas.
- So the question becomes: "Is the cat awake or asleep?".

7

COVID-19 / Re: Can covid tests also detect common colds?

« on: 13/05/2022 00:20:04 »

There are around 150-200 viruses that we classify as "the common cold". Only 4 of them are coronaviruses, so it's not really accurate to say "a cold is a Coronavirus".

You could produce a RAT test that detected one or a couple of the common cold viruses (eg adenoviruses), but it is unlikely that a single RAT test could detect all of them.

I am sure that one of the criteria for a successful COVID-19 RAT is that it did not react to the 4 "Common Cold" coronaviruses.

There are hints that people who have recently suffered from a "Common Cold" coronavirus are slightly protected from COVID-19, as their immune system responds to the family resemblance.
- This may be why children under 2 years old show some benefit from a COVID vaccine, while those 3-5 do not
- Children under 2 have lived during some form of lockdown, and may have had less exposure to the 4 "Common Cold" coronaviruses, and so may have less protection against COVID-19 than slightly older children.

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

8

Just Chat! / Re: What is your main area of interest or expertise?

« on: 03/05/2022 23:22:08 »

Philosophy should be the basis of our biggest and most influential decisions.

It has been noted that if you recursively trace the first significant word in a Wikipedia article back to its Wikipedia article, you get back to the Wikipedia entry on Philosophy (in about 95% of cases).

So perhaps Philosophy is the basis of our biggest and most influential Wikipedia articles? (in a roundabout sort of way...)
See: https://en.wikipedia.org/wiki/Wikipedia:Getting_to_Philosophy

9

General Science / Re: spherical implosions

« on: 03/05/2022 22:37:56 »

The Trinity test didn't need a perfectly spherical implosion - just good enough.
- And it worked - but they needed a much more compact arrangement if they were to fit it into a plane.
https://en.wikipedia.org/wiki/Trinity_(nuclear_test)

Another area trying to do spherical implosions today is the US National Ignition Facility, which is trying to initiate nuclear fusion with a spherically symmetrical arrangement of 192 lasers.
See: https://en.wikipedia.org/wiki/National_Ignition_Facility#Tests_and_construction_completion

10

General Science / Re: Is 2 really prime? If so, why isn't 1?

« on: 01/05/2022 04:11:50 »

There are also prime polynomials (if you ignore imaginary zeroes).
- These are important in telecommunications and encryption schemes

11

Just Chat! / Re: Free lectures

« on: 01/05/2022 04:04:08 »

There is certainly a social aspect to university (often centered more on the pub than the lecture hall).
- Some distance education programs actually have weekend or 1-week "in-person" sessions to cover some of the social/physical access components of the course.
- Australia earns a lot of income by training students from other countries at a "Western" university - and this revenue almost dried up during COVID, putting a lot of universities under severe financial pressure, leading some to shed staff.
- There is a fair bit of snobbishness about which university you attended - how could you be so snobbish if everyone had access to the best lectures by the best lecturers?

It is already hard for students to move into tenured professorships - if only the best lecturers were filmed & distributed, there would be no way to practice these skills, and develop the next generation of lecturers
- The current generation of poor lecturers would be out of a job, and their students (and the country) would probably benefit
- The ability to get individual or small-group attention for academic work is of great value, because applying the knowledge is just as hard (and probably more important) than just hearing the knowledge.
- There would need to be an ongoing commitment to tutorials and marking/commenting on student work - tasks that could perhaps be done by phD candidates to earn a bit more income?
- We have a lot of investment in physical capital of universities distributed in different places around the country - physical access to a laboratory will still be important for the physical sciences. Perhaps less so for the Arts.
- Universities would need to focus more on research and supervising research than on lecturing. But funding of research comes from a different bucket of money than tuition; so making this transition would be painful.

I am sure that things could be done better - and it will take the impact of major events like a pandemic to kick us along the path towards something better. Call me an old fuddy-duddy, but I still struggle with a comment I heard about someone learning their science from Tik-Tok...

12

General Science / Re: How to reduce cast iron melting point

« on: 01/05/2022 03:06:41 »

you get diamond powder

Carbon is very soluble in iron.
- Of the different allotropes (forms) of carbon, diamond is stable at high pressures (like > 150km beneath the surface of the Earth). At sea level pressures, graphite is more stable, so diamond is thermodynamically encouraged to slowly turn into graphite (although you can reduce the rate by cleaning it in hydrofluoric acid, with ties up a lot of the loose ends with fluorine atoms)
- One other allotrope is carbon nanotubes, and these have been formed by having tiny iron "seeds", which grow carbon nanotubes.
https://phys.org/news/2012-11-optimize-growth-individual-carbon-nanotubes.html

[Spoiler:]

13

General Science / Re: Is 2 really prime? If so, why isn't 1?

« on: 29/04/2022 10:24:37 »

Spoiler: show

Spoiler Test
Thanks!

14

Just Chat! / Re: Are The Naked Scientists Listeners open to interviews?

« on: 20/04/2022 00:33:23 »

I've sent an email to Karin (academic supervisor). I expect at least a 12-24 hour delay before I get a response.

15

Just Chat! / Re: Are The Naked Scientists Listeners open to interviews?

« on: 19/04/2022 10:51:04 »

Many people get scammed on the internet. My sentiments overlap with the concerns that EternalStudent posted in parallel.

It is important to preserve the privacy of readers/listeners, especially when dealing with a request for contact from an unknown person.

Perhaps glesphlep could reduce the "unknown person" barrier by posting details in this thread of his name, university, course, thesis topic and thesis supervisor. Those details are verifiable.

glesphlep could also indicate what type of communication they are interested in for the interview (eg Zoom, mobile phone, etc), and how long they expect the interview to take. Identify the criteria that would be used to select interviewees.

Perhaps people who have verified this identity could then send a personal message to glesphlep, identifying their general location (eg nearest city in the same timezone), and suggesting a suitable time for a discussion. Maybe mention a few details that will help glesphlep decide whether this person is an eligible candidate.

I suggest that interviewees don't give their personal email or phone number to glesphlep. Once a mutually acceptable time is agreed, the interviewee calls glesphlep. On mobile phones, Caller ID should be suppressed.

Post your interview experiences here - does it sound legitimate?

Attempts to scam forum members will be met with a prompt ban - moderator.

16

Just Chat! / Re: What is your main area of interest or expertise?

« on: 11/04/2022 21:42:19 »

I'm still fairly surprised and impressed that you reply to so many questions or discussions in the Biology sections.

One view of biology imagines it to be a fantastically complex program, coded in DNA.
- The cell represents the computer which executes the program (unlike silicon computers, it also has programs for self-repair)
- You can see parts of the program that are no longer executed, or which have been corrupted by viruses
- Each little computer interacts with others around it, at various levels up to whole ecosystems...
- Not entirely different from the telecommunications systems that I work on...

17

Just Chat! / Re: What is your main area of interest or expertise?

« on: 11/04/2022 03:54:01 »

I studied Electrical Engineering at an Australian university, but I have always had a broad interest in the sciences, mathematics and museums.
- As a youngster, fueled, I think, by electronics magazines and Isaac Asimov's fiction & non-fiction
- I studied a lot of software at university (much easier these days than back then...)
- I have spent most of my career working on software-based telecommunications systems
- In my career, I have had the privilege of traveling to many countries, and even to live in Europe for a year (for work)
- My main science-writing experience outside telecommunications has been on the Naked Scientists forum (not as a journalist or for a museum)
- I try to consider the ethical aspects of a subject, beyond the science itself
- I haven't even tried teaching my gym instructors that force, energy, power and strength are not the same thing.
- I have only contributed one short audio segment to the Naked Scientists podcast, and that was on (pseudo)random numbers.
https://www.thenakedscientists.com/podcasts/short/what-random

PS: I only saw this survey today - not all new topics pop up in my in-tray...

18

Science Experiments / Re: Hookah system

« on: 05/04/2022 23:56:55 »

If the smoke passes through the water in large bubbles, almost none of the smoke comes in contact with the water, and  it has no impact on the content of the smoke.
- This makes it about as useful as a lava lamp - visually stimulating, but doing nothing for your health
- I saw one hookah-user who put a small plastic toy in with the water; it danced around on every breath, amusing his small child...

You need to divide the smoke into very small bubbles, so it has maximum contact with the water
- This will dissolve some chemicals from the smoke
- Including many of the very small smoke particles which can reach deep into the lungs (and even into the bloodstream). These are covered with the unstable products of combustion, which can cause cancer.
- But hydrophobic molecules will pass through the water almost unchanged.

If you want to improve the hookah, put an N95 mask over the pipe...

19

Physics, Astronomy & Cosmology / Re: How does a red-shift affect a black body spectrum?

« on: 05/04/2022 10:38:48 »

An object putting out a black body spectrum is measured as such in all inertial frames of reference.
- Different Frames of reference will see the object as having a different effective temperature.

To take it to the next level: Black holes experience extreme gravitational red shift.
- According to Hawking, black holes "glow" with a black body spectrum.
- The effective temperature varies with the mass of the black hole
- A stellar mass black hole has a temperature measured in nanokelvins
- Which is why stellar-mass black holes take a long time to evaporate.

https://en.wikipedia.org/wiki/Hawking_radiation#Overview

20

Cells, Microbes & Viruses / Re: How can I find tardigrades?

« on: 04/04/2022 23:39:37 »

they seem to prefer drying out occasionally so don’t choose moss that’s damp all the time

There are many soft and squishy critters that would thrive in an environment that is damp all the time. But when it dries up, they tend to die.
- Tardigrades enter a form of suspended animation (a "tun" stage) when conditions get too harsh (eg lack of water). They reanimate when water becomes available. They can thrive in an erratic environment that would kill many other animals their size.