1

General Science / Re: Shouldn't we worry about Earth before we try to conquer Mars?

« on: 15/08/2021 08:01:38 »

I agree that we have to take care of our own planet. 

A Moon colony could be extremely helpful as a stepping stone for space exploration.  Also one could have some extraordinary lunar based telescopes. 

A Mars (or Venus) colony would be more for curiosity, or a challenge.  It could prove whether we could ever move out of the solar system.  And, would be a backup for a catastrophic event on Earth.

However, don't expect a thriving Earth/Mars tourist business, or exporting say a billion people from Earth to Mars.  It is likely that travel between Earth and Mars will forever remain expensive and arduous, and may well be limited to a few hundred, or a few thousand people ever making the trip. 

A Martian colony would have to eventually become self supporting.

2

Question of the Week / Re: 21.06.07 - QotW - What will happen to a soda can dropped in the ocean

« on: 07/06/2021 23:14:17 »

Hmmm...  Learn something every day.

All soda cans aren't created equal.


Ok, so due to different sugar contents, Diet coke has a density of about 1 g/ml, and regular coke about 1.03 g/ml.  In pure water at a density of about 1 g/ml, the can/water/gaseous CO₂ allows the diet coke to float and the regular coke to sink.

I'm seeing seawater density is about 1.02 to 1.03 g/ml. 

So the diet coke would still float, while the regular coke may or may not float. 

Drag the regular coke down say 100 meters, and all the CO₂ will be forced into solution, and the can + soda will be at higher density than the ocean, and it will sink further.

 I have no doubt the can will slowly crush with increased pressure (crushing to reduce any vapor space, as well as that 5% or so fluid compression as it drifts down to the bottom of the Mariana Trench).

3

The Environment / Re: Why is Global Warming a threat?

« on: 05/06/2021 22:57:00 »

If one looks at the Eocene Temperature Maximum, it was much hotter than it is today.



It isn't necessarily a bad thing overall.  However, it brings "Change" with it.

I.E.  Changes in our coastlines, changes in arable land, changes in storms, etc. 

And changes in species. 

However, humanity does better if everything is the same.  We don't want species to change.  We don't want deserts to become tropical forests, and farms to become deserts.  We don't want coasts to recede.  And, of course, some species to become extinct and new species to either move, or evolve (which normally might take thousands or millions of years).

Of course a little winter warming might be pleasant, but are we prepared for those 110°F summer days?

4

Plant Sciences, Zoology & Evolution / Re: How can I keep my grass short?

« on: 31/05/2021 20:25:09 »

Astroturf.

You can often buy it cheap when local stadiums remodel.

5

Plant Sciences, Zoology & Evolution / Re: How does your dog recognize you?

« on: 29/05/2021 20:23:37 »

There are videos of guys greeting their dogs after having shaved off their beards. That's a big visual difference with nothing else changed. The dogs were very confused and looked around for where the real owner was. Smell and sound was not enough when the visual image didn't match.

I've been with a beard and beardless, and Mom's dog's reaction is the same.

I think the dogs also recognize vehicles associated with people from bicycles to cars,  and those can change from time to time.

As far as visual stimuli, at times, Mom's dog will watch her while she is inside a restaurant. 

Mom doesn't whistle, I do.  At times she has been convinced her dog doesn't respond to whistles, but he responds well to me whistling. 

When Mom and Dad's previous dog was a puppy, they picked him up about 100 miles away, and we met at a restaurant on the way back home.  Everything would have been new for the puppy, but I petted it for about 1 minute in the back seat of the car.  Then I didn't see them for about 2 months.  Meanwhile the puppy developed a strong attachment to my parents, and even nipped outsiders, including my aunt and grandmother.  They were convinced that he would not like me...  but on the contrary...  I was immediately "family" within seconds of returning.  My brother hadn't had that early exposure, but I think his introduction also went reasonably smoothly.

It is hard to say.  I think the puppy remembered me from that first brief introduction, but there may be an innate ability to recognize certain family members.  It is hard to say about other smells.  Grandma always used a strong smelling hand lotion.  I don't know about the aunt.

6

COVID-19 / Re: What is understood about convalescent plasma and Covid-19 treatment?

« on: 25/05/2021 21:02:59 »

I believe there is some benefit from the monoclonal antibody treatment, especially when started early. 

Since one is fighting both the impact of the virus as well as the impact of the immune system, one would expect the antibody treatments to help knock down the virus when it is still spreading within the body, but not particularly to help clear the lungs as the disease progresses.

7

Physiology & Medicine / How close are we to global Polio Eradication, 2021?

« on: 25/05/2021 06:11:10 »

With all eyes on COVID, Polio has largely been ignored, causing some concern among health officials.

However, so far, 2021 has the fewest cases of Wild Polio Virus (WPV) ever.

https://polioeradication.org/polio-today/polio-now/wild-poliovirus-list/
https://polioeradication.org/wp-content/uploads/2021/05/weekly-polio-analyses-WPV-20210518.pdf

As of May 18, 2021, there has been exactly one documented case of Polio in Pakistan on January 27, 2021, and one documented case of  Polio Afghanistan on January 1, 2021. 

In addition, the last "other source" sample containing the virus in Afghanistan was February 23, 2021. 

There continue to be a few "other" samples in Pakistan, with positive samples on April 12, 2021 (total of 55 positive "other samples" for the year).

There do continue to be a number of circulating vaccine derived polio cases across a handful of countries.
https://polioeradication.org/polio-today/polio-now/this-week/circulating-vaccine-derived-poliovirus/
https://polioeradication.org/wp-content/uploads/2021/05/weekly-polio-analyses-cVDPV-20210518.pdf

But, even those seem to be significantly down, and seem to be close to interrupted transmission in many countries.

One thing I don't understand is that the last case of Type 2 WPV was apparently 20 years ago in 1999.  Yet, there was a huge recent explosion of cVDPV2 cases.  Was that vaccine given to children even after the virus strain was eradicated?

8

COVID-19 / Re: Can we get herd immunity?

« on: 25/05/2021 05:01:43 »

We are already seeing case numbers plunging in the USA and much of Europe. 
I still believe the disease will become a seasonal disease, and while we did get cases last summer, they weren't as many as last fall.

What we don't know is whether the case numbers will drop to essentially zero over the summer as often happens with the flu/influenza, or if we'll see numbers continually trickling in.

I am still hoping for a multivalent booster vaccine to be available this fall to help us get through the coming winter.

The problem will be whether we will get the vaccine distributed broadly enough to the third world which has been struggling to get the doses to prevent a fall resurgence of a vaccine resistant strain.

There would be a pretty extreme benefit to the richer countries to give a way a few billion doses of the vaccine to the poorer nations, and knock this thing down once and for all.

9

Question of the Week / Re: QotW - 21.05.24 - Are all snowflakes really unique?

« on: 24/05/2021 18:40:44 »

I've never really been able to successfully capture snowflakes.  But they come in a few different varieties.  At times one gets big fluffy ones.  And other times, small ones, perhaps more like a low density hail.  Generally all very much 3 dimensional.  And, I generally don't see the symmetry that 2 dimensional flakes are represented as.  Especially the amorphous big fluffy flakes.

And, of course, one sees the familiar splat of them on a car's windshield.

Then one gets into a question of what is sameness. 

Is it general morphological features, or does one get down to a single molecule?

If one takes Avagadro's number: 6.0221409 x 10²³...     602,214,090,000,000,000,000,000

Ok, so a mighty big number.  But, what is that really measuring?  The number of molecules in a mole.

Take the molecular mass (H₂O)...  so, O:16 + 2x H:1 = 18, and one gets that many molecules in about 18 grams per mole of water.  (18.01528 g/mol)

So 18 grams would be a mighty big snowflake.  And, they would obiously vary a lot in size.  So, perhaps 1/100 or 1/1000 of a mole depending on the size of the snowflake.

So, at 1/1000 of a mole, one still has  6.0221409 x 10²⁰ molecules  (602,214,090,000,000,000,000).

That would be a lot of different snowflakes.

Oof...   

That is just calculating the number of ways a single molecule could be different (in identical sized snowflakes).

But, really, it can be any or all of the water molecules could be in a different place... 

So, a factorial problem.
6.0221409 x 10²⁰ !

Now that becomes a really big number!!!

But, perhaps that isn't calculating quite what one wants.

Snowflakes would be somewhat constrained by the crystalline structure of water.  So, internal to the crystal, the water molecules would be generally constrained.  It is only on the surface where the constraints are loosened. Does the water molecule exist?  Branch point?  Are there a couple of possible orientations?

So the number of choice points gets reduced, and it becomes a density/surface problem.  Nonetheless, it is still a LOT of different configurations on the molecular level.

Likely any chance for identical flakes would not be those big fluffy ones, but small low density hail.

10

Physics, Astronomy & Cosmology / Re: Can we communicate with civilisation in anti matter solar systems

« on: 20/05/2021 18:46:05 »

As far as I know, we don`t have such technology that can allow us getting in touch with some forms of life out of the Solar system. Also, we cannot travel in other galaxies or make uncrewed missions. I`ve read recently that scientists had cought a radio wave somewhere out of our Solar system

It isn't that we couldn't communicate or find a way to communicate, but we are limited by current radio/light/laser types of communication which would be limited to the speed of light.  So, to Proxima Centauri it would take about 4 years each way (8 or 9 years RT).  Across the Milkyway could be 100 years each way, or 200 years RT.

We are certainly able to communicate with Voyager 1 & 2 at about 17½ light hours away.  Obviously not even a light day yet.  I do wonder if we could discern a weak radio signal near a star, but one could put a relay in the outer solar system to improve transmission spacial resolution.  There have also been proposals to put radio telescopes and perhaps optical telescopes on the dark side of the moon to avoid Earth's radio and light contamination.

And, obviously choose frequencies without other cosmic contamination.

The linguistic nightmare would be difficult to deal with.  Imagine having no vocabulary, and a century until your next question is answered.  But,we are able to decipher texts over a millennia old without a dictionary.

There may well be some digital universals that might help.

So, for example, there would be only a few ways to transmit a 2 dimensional black&white bitmap photo.  And, once one got a basic B&W BMP, one could start dealing with more colors and data compression, perhaps 3rd dimensions and/or time. 

Likewise for text, we have 26 letters, plus caps, punctuation, etc.  It may well be complex to decipher, but likely the character set could be discerned with stop bits and gaps.  If one believed that one was reliably sending photos, one could do photos + captions. 

Eventually one might choose to send an entire dictionary, again accentuating characters, stops, words vs definitions, etc.

With human's limited lifetime, it would certainly be be frustrating if a child would barely get a response back from a query a lifetime ago.  I.E.  generational continuity.

Travel is far more complex as we are nowhere near the speed of light.  For many reasons one would likely choose unmanned probes or even seed ships.  We could likely develop artificial wombs inclined to do so. Of course sending life to an antimatter solar system would not be of much benefit unless they had both matter and antimatter planets, or a nearby matter star.

There would be very real issues designing equipment to last hundreds, thousands, or perhaps even tens of thousands of years without maintenance.  As well as developing longterm power sources.  One could, of course, develop a sleep mode which might help, but it might be a big gable that it would all wake back up in 10,000 years (assuming no destructive impacts). 

And, of course, sending matter to an antimatter system or visa-versa would be like sending the most powerful bomb imaginable. 

Distances beyond our galaxy are just greater, and resolution more difficult to discern.

11

Question of the Week / Re: QotW - 21.05.17 - Why doesn't overcooking unhealthy food make it healthy?

« on: 19/05/2021 21:48:11 »

The result would presumably  be some kind of "soup".
Would this "soup" be safe to eat, on the grounds that the prolonged boiling had destroyed any microbes/pathogens?

I'm asking just in case it might come to that.  Best to be prepared

There are several issues with food safety. 

• Pathogens: Generally killed with cooking depending on the process, with the exception of a few very rare prions.  Simply browning the outside may not be enough.
• Biologic Toxins:  These come in a wide variety, some impacted by cooking some not. Some require high heats greater than normally used in cooking.  In some cases, they can be leached out of food with processing. 
• Metals, inorganic toxins, and certain small molecule toxins.  Not impacted by cooking, although they may be able to be leached out

Rapeseed is mildly toxic, but the oil can be extracted and is edible.

Anyway, cooking your moldy bread may render it harmless, or it may not.

Botulism Toxin is deadly, but generally rendered safe with significant cooking.
Staph Aureus Toxin is more mild "food poisoning", but is quite heat resistant.
Cyanide C≡N is also resistant to heat.
Obviously metals generally would not be removed by cooking, but could have oxidation states impacted.

I can't say about your concoction.  It may be safe, or it may not.  It would depend on the specific organisms involved.  Note that "blue cheese" is a "moldy cheese" that is edible  and very popular.

12

Physics, Astronomy & Cosmology / Re: Can we communicate with civilisation in anti matter solar systems

« on: 18/05/2021 18:26:43 »

The more likely number is zero.

I agree,it is unlikely that we'll have them in this Galaxy, but perhaps there could be relatively isolated entire galaxies somewhere.  Even something like Cosmic Rays would be incredibly damaging to an antimatter cluster.

In theory there should be no problem, but I would not recommend visiting their planet or them visiting our planet and shaking their hands would be a right bad idea.

If one could reach an Antimatter rogue planet, solar system, galaxy, etc...  it would put our space system ahead a thousand years. 

It is hard to imagine any commodity that would drive trade between solar systems, but if there was, it would be matter/anti matter trade.

Just imagine the value of say a ton of anti-mercury or anti-iron. 

And an anti-matter system would be equally happy to receive "normal" matter in trade.

13

That CAN'T be true! / Re: Why are atheists despised and ridiculed?

« on: 16/05/2021 21:19:41 »

Christianity may teach that not knowing "God" is bad, or that there is "One True God".  Yet there are hundreds of different interpretations of who that "God" actually is.

Christians believe they are "God Fearing", whatever that means.  But, it may lead to a belief that morality can only be derived from God.

Yet, this may lead to a misinterpretation of atheists, or those that don't believe in any god. 

One can derive morality from many sources, including empathy and "do unto others as you'd have others do unto you", which doesn't have to include a belief in any mythical figurehead.

Atheists are also unlikely to believe in an "original sin".  Thus, one can take responsibility for one's shortcomings, and not blame it on the human condition or any deity.

14

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

« on: 02/05/2021 13:21:51 »

Infectious organisms aren't just completely go with the flow. 

Malaria is a disease of the Plasmodium Protozoa.  There are some indications that blood levels of the organism increases during hours with peak mosquito activity, an adaptation to enhance spread.

Viruses don't have intelligence, but have evolved to spread, and are often very selective in the kinds of cells they infect, whether it is upper respiratory tract cells, hoping to be coughed up.  Other viruses are selective for the GI tract for fecal/oral transmission.  And, others are STDs.  And others make growths on skin or mucosa, and transmit with skin contact, or sloughing skin.

And, of course, some viruses like Rabies can cause behavioral changes in their hosts to improve transmission.

15

Physiology & Medicine / Re: Is marijuana intoxication while driving just as dangerous as alcohol?

« on: 24/04/2021 18:34:35 »

I think the data is ambiguous.  Alcohol + Marijuana is supposed to be worse than either alone.

Apparently Marijuana does impact a number of things related to driving.

• Inability to concentrate and maintain attention
• Difficulty performing divided-attention tasks
• Reduced hand-eye coordination
• Distortion of time and distance
• Increased evaluation, decision, and reaction times
• Sleepiness
• Hallucinations

So far the number of pot intoxicated traffic deaths is far behind those of alcohol.  But, even in places pot is legal for both recreation and medicinal use, the numbers of users may still be limited making direct comparisons to alcohol difficult.

16

Physics, Astronomy & Cosmology / Re: Can you measure the one way speed of light without synchronised clocks?

« on: 19/04/2021 06:36:11 »

It should be fairly easy to calculate the one-way speed of light.  The problem is doing so with any reasonable amount of accuracy.

Here's how I would do it.


SpeedOfLight.gif (9.32 kB . 669x311 - viewed 45731 times)

Light (strong laser) passes through two shaft connected spinning discs, hits a cylindrical (conical) mirror, and is projected onto a wall to record.  Mostly interested in the trailing edge of the light spot.

Light speed  is: 299,792,458 m/s.

So, say the two discs are spaced 10 meters apart, then it will have traversed the gap in about 1/(29,979,245) s

Say the discs are 2 meters in diameter, and spinning at 60,000 RPM (1,000 RPS).  With a circumference of πD, or 6.28 m.

So, your discs are spinning at 6,280 m/s.

Multiply the two, and one gets about 1/4774 m, or .0002094 m  (2x10^-4)

Multiply by 1000, and one is 0.2094 mm

That is well within the range one can discern.

The problem is the accuracy of the reading.  If one uses UV light, one might be able to get down to 100nm accuracy, or about 1x10^-7 m. 

So that gives one about 3 digits of accuracy.  One may be able to add a 4th digit, or even 5th digit by going with a faster shaft speed, longer shaft, larger discs, etc.  Perhaps using X-Rays if they could be reflected on the cylindrical mirror (or mirror pair).

So, the question is would say 3 or 4 digits of accuracy matter?

Now, let's consider some kind of unknown aether or fabric of space(time). 

What is the fastest object known to man?  well, Earth is a good candidate.

The equator is rotating at about 460m/s.  And, even doubling it for the difference of forward rotation vs reverse rotation with respect to the fabric of space during the 24 hour day, and it still isn't fast enough.

Earth's orbital velocity around the sun is about 29,780,000 m/s, or about 1/10,000 the speed of light.  And, still not fast enough to pick up.  Earth's orbital speed around the Milky Way is about 220,000 m/s, and getting close to 1/1000 the speed of light.  And, the Milky Way is moving at about 600,000 m/s.

Now, if our aether or fabric of space is not distorted by gravity, electrical fields, matter, etc, then one can choose a place to orient one's device East/West with respect to the galactic rotation or motion, or North/South with respect to the motion.  This should give comparative velocities, but one is just barely on the cusp of being able to pick it up.

(oops, I got a conversion factor to mm off... but it means it is easier to snag the first digit of the speed of light with the theoretical machine, but still a difficult task to get multiple digits of accuracy).

Ok, thinking about this more, there are issues with the leading edge of the light from the first slot illuminating the trailing edge from the second slot making timing difficult.

One would likely fix that by either adding an adjustible flat mirror to the inbound light, or slightly changing the direction of the source.  Adjust to both maximize the intensity of the output beam as well as maximizing the beam width coming off of the cylindrical mirror.

A concave mirror rather than a convex mirror would also work, but would flip the image.  Parabolic?

17

Geology, Palaeontology & Archaeology / Re: Why does the planet's water remain on Earth?

« on: 15/04/2021 18:49:35 »

Earth can't hold the lightest of molecules (Hydrogen, Helium, etc).

One would expect a greater abundance of lighter inert gases in our atmosphere (higher prevalence in galaxy), but what we find is:
Helium (Atomic mass 3 or 4), 5ppm, almost all ⁴He which is a nuclear decay product, and  ³He is very rare.
Neon (Atomic mass 20), 18 ppm
Argon (Atomic mass 40), 0.9% (9000 ppm)
Krypton (Atomic mass 85) 1 ppm
Xenon (Atomic mass 131) 0.09 ppm

So, Earth is pretty good at holding onto Argon (Atomic mass 40), and heavier gases, but loses the lighter ones.

Atmospheric compounds:
H₂O, Molecular mass: 18
N₂, Molecular mass: 28
O₂, Molecular mass: 32
CO₂, Molecular mass: 44

So, one would expect any H₂O that evaporated to go the way of Neon and escape our atmosphere.

HOWEVER, water tends to be very sticky when cold.  So, it will slowly evaporate around room temperature, but it will strongly form water droplets and ice as temperatures are dropped.



So, as one gets up into the upper troposphere/lower stratosphere, it gets mighty cold, and condenses out the water and it falls back to earth as rain, hail, and snow.

Note that the temperature zigs and zags a bit.  It may be that our Ozone layer helps keep it hotter in the stratosphere, and cooler at the cloud level, and is vital to keeping our water.

The other thing that happens is that Hydrogen will float away as H₂, but strongly binds to oxygen (H₂O), and various carbon compounds, and other elements.  Thus keeping our Hydrogen on Earth.

18

Physics, Astronomy & Cosmology / Re: How long could humanity survive if the sun went out?

« on: 15/04/2021 17:48:29 »

All heat wouldn't disappear overnight, but within a few days the Earth would be plunged into sub-zero temperatures.  And, within a month, perhaps down to a few degrees Kelvin. 

Geothermal energy would last for quite some time.  So deep mines and caves would offer substantial protection potentially for years. 

Growing new food would become a major problem, but say there were a few thousand survivors, they might be able to scavenge food for decades.  Likewise, the oxygen/CO2 cycle would be problematic, but our existing atmosphere could support a small group of survivors for a very long time.

Planning would be key, so if given years or decades warning, people could dig underground, store supplies, build robots,etc.  Ensure longterm nuclear power.  Of course, it would be better for longevity of the planet if the survivor numbers were kept low.

19

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

« on: 10/04/2021 19:22:08 »

The "Nuclear Winter" scenario has never been empirically tested.  I doubt that it represents the truth.  It was invented  during the SALT negotiations of the 1970/80's.  To scare people.

There is actually empirical evidence for it, and even in recent history.

1816 is known as "The Year Without A Summer".  It is believed to be the result of a massive volcanic eruption of Mount Tambora, causing global cooling the following year.

I'm seeing some estimates of around 100,000 deaths, but today that number could be far greater, perhaps in the millions.  Hopefully not reaching the billions.

20

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

« on: 08/04/2021 12:02:35 »

I would think that any prediction of an impact would also have to include a time of day and direction, from which one should be able to determine a likely hemisphere of the impact.

Although, that would depend on whether it is coming in on a tangent to Earth's orbit where there may be some variance in the calculation, or at a greater angle up to perpendicular where an hour could mean the difference between hitting and missing.

If one knows where it is going to hit, there could be significant preparations possible from moving refugees to ensuring a food supply for survivors (which may be somewhat contradictory goals).

And, of course, attempts to either move it, or shatter it. A shattered asteroid might have a larger debris field, but each fragment would likely be eroded more by atmospheric entry, and one would get may smaller impacts rather than one large impact.

Nonetheless, I'd vote for informing governments, and the people.