41

Physics, Astronomy & Cosmology / Re: How important is it to recreate Earth's gravity on a manned spaceship?

« on: 21/02/2023 07:17:32 »

In a weightless independant frame relativity obviously dictates there can be no acceleration to any other gravitational body.

The ISS is a weightless (microgravity) environment  (except when the rockets are firing)
- The ISS is being continually gravitationally attracted to the Earth.
- The ISS is being continually accelerated towards the Earth (but it continually misses, due to its large horizontal velocity).

A spaceship to Mars is a weightless (microgravity) environment (except when the rockets are firing)
- A spaceship to Mars is being continually gravitationally attracted to the Sun.
- A spaceship to Mars is strongly gravitationally attracted to the Earth at the start of its journey.
- A spaceship to Mars is strongly gravitationally attracted to the Mars at the end of its journey.
- A spaceship to Mars is being continually accelerated towards the Earth, Sun and Mars (in different ratios and in different directions at different parts of the journey).

42

Geology, Palaeontology & Archaeology / Re: Why do insects fly?

« on: 20/02/2023 20:24:49 »

Apparently, flowering plants evolved about 130 million years ago.

But flying insects reached their maximum size about 300 million years ago, supported by higher oxygen levels than today.
Some had wingspan of up to 70cm. Some were insectivores (like dragonflies today), but there was obviously something nutritious at the base of the food pyramid...
https://news.ucsc.edu/2012/06/giant-insects.html

Maybe your hydrogen car economy could be supported by solar-powered home electrolysis, storing hydrogen and driving fuel cells in the evening?

43

General Science / Re: Good examples of contemporary computational/theoretical engineering/physics rese

« on: 20/02/2023 09:36:48 »

both computational as well as experimental in every paper

Computation has become such a common way of studying phenomena that there is even a name for it: in silico

Traditionally, biology experiments have been done:
- in vivo: in living organisms
- in vitro: in a glass dish (eg Petri dish)
- in situ: as found in nature

We now have:
- in silico: Done in a computer (silicon chips being the basis of today's computer hardware)

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

44

Just Chat! / Re: What are ways to protect yourself from falling satellites?

« on: 19/02/2023 09:25:11 »

Which two decades was that?

The following article suggests that nobody has yet been killed by a falling man-made satellite
- And they estimate a 10% chance that a falling satellite could kill somebody(s) in the next decade
- They are obviously excluding the German space rockets that were launched during World War 2 (...they were ballistic missiles and never actually entered orbit, so could not be considered "satellites").
https://www.open.ac.uk/research/news/scientists-calculate-risk-someone-being-killed-space-junk

45

General Science / Re: Good examples of contemporary computational/theoretical engineering/physics rese

« on: 19/02/2023 09:17:18 »

That question is so broad that it is hard to give a meaningful response.

For a starter, the title mentions engineering/physics research
- While the body of the question only mentions computational research
- The title only mentions theoretical research, while the body adds experimental research
- Most theoretical research in any field involves computation
- Most experimental research (including in computation) involves building things

Some extreme examples:
- Manipulating real stars and galaxies is far beyond our capabilities, so cosmology is one area of research which is dominated by theoretical & computational methods.
See: https://en.wikipedia.org/wiki/Illustris_project
- Manipulating real protons and lead ions has become more effective over the past 50 years. So the Large Hadron Collider at CERN does experiments in nuclear physics. Processing and storing and analysing the results involves lots of computation, which is why CERN originated the concepts between today's World Wide Web, and Cloud Computing.
See: https://en.wikipedia.org/wiki/CERN

46

Physiology & Medicine / Re: Akathisia and the Rights of the Mentally Ill...

« on: 17/02/2023 20:46:32 »

I've been listening to a podcast series from Flash Forward, called Vanguard Estates, a mythical home for people with aging, cognitive impairment and dementia. They use this theme to "look at some of the real science, policy, economics, law and ethics (of) living with dementia".
- They comment on the overuse of anti-psychotics in aged care, and a Royal Commission in Australia that reported on their misuse (even though we don't have any local Royals)
- They suggest that to get around the reporting on anti-psychotics, some psychiatrists are now prescribing high-dose anti-histimines, which have a sedative effect, but also other side-effects

An interesting series - here is one episode from the series (around 5 in the series)
https://podcasts.apple.com/us/podcast/vanguard-estates-living-with-dementia/id994349813?i=1000585332275

47

General Science / Re: What could make Artificial Intelligence by Google Deepmind and OpenAI + phones?

« on: 16/02/2023 20:09:34 »

Smartphones already use AI techniques like neural networks for:
- In the camera, detecting faces, drawing a box around them, and adjusting focus/brightness to clarify the faces
- Attached to the microphone, to detect "Hey Siri" (or similar), to wake up the phone
- Via a base station to perform fancier analysis in the cloud, like general speech analysis, eg "Give me directions to home".

Some cars use AI techniques to determine when to change gears, to avoid hitting the car in front, or to follow lane markings.

48

Physiology & Medicine / Re: How does anesthesia medicine have recreational aspects?

« on: 16/02/2023 19:59:31 »

Sir Humphry Davy could be considered a recreational chemist.
- He built a gas chamber to expose himself to all the gases he created.
- He experienaced nitrous oxide this way
- But in general, I would describe this as A Bad Idea.
https://en.wikipedia.org/wiki/Humphry_Davy#Pneumatic_Institution

49

Technology / Re: Does wi-fi harm the environment?

« on: 15/02/2023 20:21:47 »

electromagnetic radiation.... damages DNA

It is true that electromagnetic radiation at UV and higher frequencies does damage DNA by breaking the chemical bonds; sometimes that damage cannot be repaired by your cells. That's why you should use sunscreen if you are going to spend a long time in bright sunlight.

However, visible and Infra-Red radiation have too low energy per photon to break DNA bonds.
- The frequencies used by WiFi and 5G cellular towers are much lower again, and cannot break bonds in DNA
- Your phone can get hot, and the radiation can also heat the skin; if you feel your ears burning, it's time to switch to hands-free.

50

Plant Sciences, Zoology & Evolution / Re: Is eugenics possible?

« on: 15/02/2023 08:08:25 »

Diseases produce a very strong evolutionary pressure on humans.
- But a random gene variant which makes us more resistant to a particular virus or other parasite is rarely what a human would call "good" genetics
- An extreme example is sickle-cell disease; a gene variant producing a slight resistance to malaria results in a crippling disease in those with 2 copies of this gene variant
https://en.wikipedia.org/wiki/Sickle_cell_disease
- Other similar genetic examples are available....

"Goodness" is in the eye of the beholder, as seen in some particular environment.

51

Plant Sciences, Zoology & Evolution / Re: Is it possible to ride a kangaroo?

« on: 14/02/2023 19:54:34 »

Note that kangaroos have a very low center of gravity - you would not be riding high on their backs, but low on their belly (roughly where the joey sits).

I heard about a military helicopter simulator, where one of the conditions was that it would emulate the action of kangaroos, which can give away your position by fleeing from an invisible helicopter.
- In the acceptance tests for the simulator, a helicopter approached a mob of kangaroos, and they bounded away in a very realistic manner.
- Then one of the kangaroos stopped, turned around, and fired a rocket-propelled missile at the helicopter
- It turned out that in simulating the mob of kangaroos, the manufacturer had repurposed an existing model for a platoon of infantry - they changed the icon, lengthened the stride, and dialled up their anxiety. They forgot to disarm them.

If it's a family of roos, you find somewhere else.

Kangaroos are most active around sunrise and sunset, so avoid those times...

52

Plant Sciences, Zoology & Evolution / Re: Is eugenics possible?

« on: 13/02/2023 20:18:20 »

Eugenics is performed all the time as part of mate selection. Darwin saw that.

There are some areas where eugenics is carried out voluntarily, assisted by technology - in the case of families with genetic diseases:
- If the parents are known to be carrying a genetic disease, pre-implantation genetic diagnosis can be used to select embryos which do not carry the disease. But it is a difficult process for the parents. https://en.wikipedia.org/wiki/Preimplantation_genetic_diagnosis
- Amongst certain populations with a high level of dangerous recessive genes, an anonymous teenage genetic profiling service is available. Teens interested in a relationship can anonymously check if their genes are compatible (a baby with 2 recessive genes could suffer from a severe genetic disease),  and genetic counseling is available if they don't like the answer.
https://en.wikipedia.org/wiki/Dor_Yeshorim
- But some particularly biased and brutal attempts have certainly given eugenics a bad name!

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

53

Plant Sciences, Zoology & Evolution / Re: Is it possible to ride a kangaroo?

« on: 13/02/2023 20:03:40 »

Male grey kangaroos are typically under 70kg, while females typically are under 40kg.

So, conceivably, a small child could ride an adult male kangaroo.
- But I've never seen it done
- It would be dangerous - these males are strong and have a powerful kick (especially aggressive during mating season)
- The tendons in their legs act as a spring, to conserve energy when hopping. If your mass is 50% higher due to a passenger, the spring might break, or at lest be less effective, limiting speed and endurance

54

Just Chat! / Re: But Maybe Things Were Dirtier In The Past...

« on: 12/02/2023 20:16:21 »

I think that there is more recognition of the "consenting" part today - to the extent that the male lead sometimes has to wait for consent to kiss the femaie lead.

And there are a lot more women in lead roles - I was watching Wakanda Forever, and most of the dominant lead characters are female (apart from the anti-hero, who is male...).

55

Plant Sciences, Zoology & Evolution / Re: The Speed of Life

« on: 11/02/2023 19:57:38 »

every amoeba is arguably tens of millions of years old

Scientists were surprised that life survives deep underground.
It is thought that the metabolic rate there is 10,000 to 1 million times slower than at the surface, with individual amoeba cells dividing perhaps once in 1,000 years.
It is thought that 90% of Earth's bacteria & archaea live in this deep underground zone (not at the surface, which is what we are normally exposed to).
This may provide some indications that life could exist elsewhere in our solar system.
https://en.wikipedia.org/wiki/Deep_biosphere#Living_with_energy_limitation

56

Plant Sciences, Zoology & Evolution / Re: The Speed of Life

« on: 10/02/2023 19:58:14 »

ionising radiation can induce defects in nucleic acids

There are some very hardy critters which can stand high levels of radiation.

Deinococcus survives 5,000 Greys (5 Greys will kill a human)
https://en.wikipedia.org/wiki/Deinococcus_radiodurans#Ionizing-radiation_resistance

5,000 Greys will kill half of tardigrades:
https://en.wikipedia.org/wiki/Tardigrade#Physiology

One reason elephants don't die of cancer at a young age is because they have 20 copies of the P53 gene that detects and destroys cells with DNA damage (compared to 1 in humans).
https://en.wikipedia.org/wiki/Peto%27s_paradox#Evolutionary_considerations

57

New Theories / Re: What is the real readshift in the Cosmic Microwave Background (CMB)

« on: 08/02/2023 07:53:26 »

the size of the Universe was about 92BLY....(or)  15 billion light years, than why they can't tell us how big it is.

There are some people on this forum who can explain this...

My simplistic understanding of what they said is:
- Roughly 15 (or 14) billion light years is the distance from "where the source was when the light was emitted" to "where we are now"
- Roughly 100 50 billion light years is the distance from "where the source is now" to "where we are now"
- There is an even smaller number (1.5 Million Light years) which represents the distance from "where the source was when the light was emitted" to "where we were back then"

As relativity illustrated, all times and distances are relative to which frame of reference you are talking about
- And anything outside your light cone is irrelevant to you (eg if some object is now 100 billion light-years away, light from that object will probably never reach us, due to the expansion of the universe).

I apologise to those whose clear-sounding explanation I have mangled.... Please post an accurate description.

PS: See more corrections from Halc, below

58

Physics, Astronomy & Cosmology / Re: How important is it to recreate Earth's gravity on a manned spaceship?

« on: 07/02/2023 21:23:51 »

The best thing about being on the Moon is that I could finally go to the toilet

Apparently, digestion does not work so well in micro-gravity.

These days, there are supplements that can help with digestion, according to astronaut Mike Massimo, interviewed here:
https://www.thenakedscientists.com/podcasts/astronomy-podcasts/space-boffins/mike-massimino-and-meet-minister

59

Just Chat! / Re: What is your theodicy?

« on: 07/02/2023 19:25:32 »

theodicies  from ChatGPT

...and what is ChatGPT's theodicy?

60

Geology, Palaeontology & Archaeology / Re: Volcanic Eruptions?

« on: 05/02/2023 08:34:23 »

This site suggests that the rate of large eruptions has not really changed (as a 10 year average).

The apparent increase in activity reflects increases in populations living near volcanoes to observe eruptions and improvements in communication technologies to report those eruptions.

https://volcano.si.edu/faq/index.cfm?question=historicalactivity