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A scientific fact/tidbit you recently learned that you thought was interesting

"There is no dark side in the moon, really. Matter of fact, it's all dark."

Actually spoken (thought up?) by Gerry O'Driscoll, the doorman at Abbey Road Studios.
 
Just watched that last night, pretty funny.
I have this weird feeling I haven't seen a clip of Don in ages, years and years, and now that and another couple pop into my feed.
 
NPR this morning. Talking about why people get fixated on video games, social media, online shopping, etc. It's known these activities produce dopamine in the brain, but it turns out dopamine isn't a "pleasure" or "reward" neurotransmitter as I'd thought. It actually tells the brain "This is important. Critical to survival. Pay attention, pay attention, pay attention!"
 
Measles is such a dangerous disease because it directly targets the Memory T and B cells.

When you are fighting an infection, T and B cells are part of the immune system response. Together they are involved in flooding the bloodstream with antibodies tailored to attack the pathogen. But a few of them hide themselves away in the lymph nodes and chill out, not producing antibodies, but instead just "remembering" how to produce them. Then when you are subsequently re-infected by the same pathogen, they can respond very quickly. This is acquired immunity, and the reason you usually only get chicken pox or mumps once in your life (Yes, sometime people can get re-infected. Immunity is complicated!). The Memory cells recognise the invader almost immediately and the infection can be wiped out almost before you even notice it.

Measles directly attacks these Memory cells, effectively erasing the acquired immunity that a body has built up.

Measles is bad.
 
arthwollipot said:
A fever helps your immune system and hinders pathogenic invaders basically because your cells are bigger, and have more innate mechanisms by which they can withstand the higher temperatures.
Click to expand...

Skeptic Ginger said:
Really? So cells are bigger as opposed to better vascular circulation?

How do bigger cells increase the number of innate mechanisms?
Click to expand...

I think he meant bigger than the pathogenic invaders: viruses and bacteria.

I could be mistaken, but it sort of reminds me of a strategy used by some honeybees to defend against larger predatory hornets, although in that case its a bit the other way around. The invaders are larger but fewer in number. The honeybees mass around them in a ball, and apparently the temperature in the middle of the ball gets hot enough to kill the hornets. It's a bit like a fever in that way. Using heat to fight an enemy.
 
Puppycow said:
I think he meant bigger than the pathogenic invaders: viruses and bacteria.
Click to expand...
Yes, that's what I was talking about - pathogens in particular. Skeptic Ginger was absolutely correct in that there are thermophilic organisms, but those organisms likely have equivalent cellular mechanisms to mitigate the effects of excess heat (heat stress proteins were mentioned, but I don't know what they are). And I doubt that many of them are actually pathogenic.

I would have mentioned this, but the thread had already moved on. :p
 
arthwollipot said:
Yes, that's what I was talking about - pathogens in particular. Skeptic Ginger was absolutely correct in that there are thermophilic organisms, but those organisms likely have equivalent cellular mechanisms to mitigate the effects of excess heat (heat stress proteins were mentioned, but I don't know what they are). And I doubt that many of them are actually pathogenic.

I would have mentioned this, but the thread had already moved on. :p
Click to expand...
Well allow me to move it back, briefly. ;)

One would think since cooking one's food renders it safe to eat, you should be able to 're-cook' so to speak, food that has been left out unrefrigerated. Why do we tell people not to let their turkeys thaw on the counter?

Well it turns out some staph bacteria create a heat resistant toxin. You recook that turkey and you kill the bacteria. But you don't denature the toxin the bacteria have left behind.

Bummer, 24 hours of intense vomiting. Next time you'll plan ahead and thaw that turkey in the fridge. :p

Thermal stability and structural changes in bacterial toxins responsible for food poisoning
... while SEH adopted an extremely stable structure at neutral pH, with almost no effects on secondary structural elements upon heating to 95°C, and with reversible formation of tertiary structure upon subsequent cooling to room temperature. Taken together, the data suggests that the family of staphylococcal enterotoxins have different ability to withstand heat, and thus the exact profile of heat inactivation for all SEs causing food poisoning needs to be considered to improve food safety. ...

The secondary structure is still present after heating and subsequent cooling for SEA and SEE ...

Some SEs clearly aggregate upon heating, while other can persist as biologically intact molecules and adopt non-native structural conformations that may be reversible upon cooling. Here we show that SEA and SEE aggregate upon heating in most conditions, which correlates well with previously published data [13]. However, at pH 5.0 in the presence of Zn2+, secondary structure elements persisted heating for both SEA and SEE and hydrophobic elements buried in the native fold, were exposed to the environment, indicating formation of an alternatively folded state. ...

At the tertiary structural level, the toxin did unfold, but upon cooling it re-gained its tertiary structure. Interestingly, SEH has commonly been associated with SFP outbreaks caused by dairy products, which has neutral pH. Hence, our data supports that SEH could retain its three-dimensional structure during thermal processing of dairy products at neutral pH. ...
Click to expand...
It's all about that folding, that folding ... sorry, had an attack of an ear worm.
 
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Skeptic Ginger said:
Well allow me to move it back, briefly. ;)

One would think since cooking one's food renders it safe to eat, you should be able to 're-cook' so to speak, food that has been left out unrefrigerated. Why do we tell people not to let their turkeys thaw on the counter?

Well it turns out some staph bacteria create a heat resistant toxin. You recook that turkey and you kill the bacteria. But you don't denature the toxin the bacteria have left behind.

Bummer, 24 hours of intense vomiting. Next time you'll plan ahead and thaw that turkey in the fridge. :p
Click to expand...
Thanks for that. Good advice. :D

Regardless, the one interesting thing that this book is ramming home is that the human immune system is one of the most arcanely complex interlocking set of cells, proteins and signalling pathways in the known universe.

Michael Behe once cited the immune system as one of the reasons to believe that living beings were intelligently designed. Well, if it were, then the so-called "intelligent" designer was a lunatic on meth. No intelligent being in their right mind would ever design something this ridiculously complicated.
 
Something other than the immune system for a change, because I am not a one-trick pony:

A mutation in the human genome caused the Mafia.

During the 18th century, scurvy killed more British sailors than any naval action. Scurvy is caused by a mutation in the human genome which removed our ability to make our own Vitamin C. So sailors spending a long time away from land and fresh food developed a deficiency.

The Royal Navy started issuing preserved lemon rations to its sailors during the Napoleonic wars, which created a sudden massive demand for lemons. They decided that Sicily was a good place to grow them.

Sicily at the time was a pretty lawless and ungoverned place, so the lemon growers had to hire, shall we say, "private security" to protect against lemon thieves (since lemons were in such a high demand and fetched a nice price on the black market). Over time, this developed into what we now know as the Sicilian Mafia.

Source: New Scientist podcast interview with Lewis Dartnell, author of a series of books that explains how human biology interacts with the environment.
 
arthwollipot said:
A mutation in the human genome caused the Mafia.
Click to expand...

Small nitpick, but I don't really like this phrasing. It's not wrong, but because of ambiguities of the English language, it can be interpreted in ways that are wrong. Specifically, one might conclude from this that the mutation made the Mafia inevitable. But that's not the case. It's only a confluence of circumstances, only one of which was this mutation, which led to the Mafia. Under other conditions, this mutation wouldn't have done that. I think a better (but still not perfect) phrasing would be that a mutation led to the formation of the Mafia.
 
SteveAitch said:
"There is no dark side in the moon, really. Matter of fact, it's all dark."

Actually spoken (thought up?) by Gerry O'Driscoll, the doorman at Abbey Road Studios.
Click to expand...

Yes, but he 'was very drunk at the time'.
 
Ziggurat said:
Small nitpick, but I don't really like this phrasing. It's not wrong, but because of ambiguities of the English language, it can be interpreted in ways that are wrong. Specifically, one might conclude from this that the mutation made the Mafia inevitable. But that's not the case. It's only a confluence of circumstances, only one of which was this mutation, which led to the Mafia. Under other conditions, this mutation wouldn't have done that. I think a better (but still not perfect) phrasing would be that a mutation led to the formation of the Mafia.
Click to expand...
Yes, on reflection that would probably be better.
 
About 3/4 of all stars in the universe are red dwarfs, and they are unlikely to support life.
 
bigred said:
About 3/4 of all stars in the universe are red dwarfs, and they are unlikely to support life.
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Why the latter?

Red dwarf stars last much longer than stars like our sun, so the window of opportunity for life to begin and evolve in such systems would be immense. Earth was already about two thirds of the way through its window when complex life evolved here.
 
The low light & temperature means that, for a planet to be warm enough for liquid water, it would need to be so close to the star that it would be highly exposed to any solar/stellar wind it produces and any flares, ejections, & other changes in the star's output (which I think I recall those stars have more frequently anyway). Also, the planet at such a short distance would probably be tide-locked, which means having a permanently roasted side and a permanently frozen side, with horrific winds in the ring where they meet, if there somehow is an atmosphere.
 
Proximity to a star is not essential for liquid water. There are oceans of water under the surface of several of the moons of Jupiter and Saturn, where life might well exist.
 
Well, more accurately what's needed is a source of energy, otherwise the whole planet will reach equilibrium with the temperature of the CMB, which is to say, less than 3 Kelvin. That's not just enough to freeze water, but even hydrogen. (Hydrogen freezing points is about 14 Kelvin.)

Of course tidal energy from a big planet or internal processes or whatever, still counts, which is what's happening with those moons.
 
Well, what I learned recently: Hi, my name is Hans and I'm stupid. A stupid audiophile, to be exact. Turns out that getting a sound card that does 32 bits sampling at 384 kHz makes no difference whatsoever:

 
HansMustermann said:
Well, more accurately what's needed is a source of energy, otherwise the whole planet will reach equilibrium with the temperature of the CMB, which is to say, less than 3 Kelvin. That's not just enough to freeze water, but even hydrogen. (Hydrogen freezing points is about 14 Kelvin.)

Of course tidal energy from a big planet or internal processes or whatever, still counts, which is what's happening with those moons.
Click to expand...

The main source of heat of planet Earth is radioactive decay, isn't it? A rocky planet of the right size, somewhat larger than our planet I'd think, would have the right surface-to-mass ratio, given a concentration of radio-isotopes, that heat from decay would be in equilibrium with net heat radiation away from the surface, such that temperatures conductive to maintaining life are present near enough to the surface.
 
Actually, no, not really. Earth receives 44 quadrillion (4.4 x 1016 W) watts of energy (well, ok, POWER) from the Sun. Earth's core is estimated to produce about 44 terawatts (4.4. x 1013 W). That's 0.1% of the energy that comes from the Sun, or about the same percentage of the total energy.

Going Stefan–Boltzmann on its ass, we're talking about a difference of (T1/T2)4=1001, then T1/T2=5.6 (slightly rounded down.) But that's in Kelvin, so T1 (current temp) is an average 288 Kelvin, while T2 (without the sun) would be about 288/5.6=about 51.4K. (Again, rounded to one decimal, because we're just doing back of the napkin taking-the-piss.)

That's not just low enough to freeze water, it's low enough to freeze the nitrogen (freezing point: 77 K) in the atmosphere and juust barely enought to freeze the oxygen too (freezing point: 54.4 K). Well, ok, maybe not entirely the latter, since that's at 1 atm, which would no longer be the case. A very thin atmosphere would be left above the ice, but with most of the nitrogen missing, and the Earth's magnetic field stopping (no ocean => no plate tectonics => not much rotation of the core) most of it would be blown away by the solar winds.


So not on the surface, no.

On the other hand, in the depth of the ocean near the volcanic vents, there would be pockets of liquid water that could support bacterial life.
 
HansMustermann said:
That's not just low enough to freeze water, it's low enough to freeze the nitrogen (freezing point: 77 K) in the atmosphere and juust barely enought to freeze the oxygen too (freezing point: 54.4 K).
Click to expand...

Just to quibble, nitrogen freezes at 63K, 77K only liquefies it. Still cold enough to freeze it though.

Dave
 
HansMustermann said:
Well, more accurately what's needed is a source of energy, otherwise the whole planet will reach equilibrium with the temperature of the CMB, which is to say, less than 3 Kelvin. That's not just enough to freeze water, but even hydrogen. (Hydrogen freezing points is about 14 Kelvin.)

Of course tidal energy from a big planet or internal processes or whatever, still counts, which is what's happening with those moons.
Click to expand...

And which could also be happening on moons in the planetary systems of red dwarfs, so such systems could support life. If we rule them out because there would be no planets in the Goldilocks zone, as was suggested, we might be significantly underestimating the number of possible abodes of life in the universe.
 
HansMustermann said:
Actually, no, not really. Earth receives 44 quadrillion (4.4 x 1016 W) watts of energy (well, ok, POWER) from the Sun. Earth's core is estimated to produce about 44 terawatts (4.4. x 1013 W). That's 0.1% of the energy that comes from the Sun, or about the same percentage of the total energy.

Going Stefan–Boltzmann on its ass, we're talking about a difference of (T1/T2)4=1001, then T1/T2=5.6 (slightly rounded down.) But that's in Kelvin, so T1 (current temp) is an average 288 Kelvin, while T2 (without the sun) would be about 288/5.6=about 51.4K. (Again, rounded to one decimal, because we're just doing back of the napkin taking-the-piss.)

That's not just low enough to freeze water, it's low enough to freeze the nitrogen (freezing point: 77 K) in the atmosphere and juust barely enought to freeze the oxygen too (freezing point: 54.4 K). Well, ok, maybe not entirely the latter, since that's at 1 atm, which would no longer be the case. A very thin atmosphere would be left above the ice, but with most of the nitrogen missing, and the Earth's magnetic field stopping (no ocean => no plate tectonics => not much rotation of the core) most of it would be blown away by the solar winds.


So not on the surface, no.

On the other hand, in the depth of the ocean near the volcanic vents, there would be pockets of liquid water that could support bacterial life.
Click to expand...

How do you get from no plate tectonics => not much rotation of the core?
 
rjh01 said:
It would be very small life forms. Probably like what exists in our ocean vents.
Click to expand...

I don't see why. Some of those oceans are immense, and unless I'm missing something (which is entirely possible) I would think the conditions that are suitable for life would prevail across fairly large regions of them.
 
Pixel42 said:
And which could also be happening on moons in the planetary systems of red dwarfs, so such systems could support life. If we rule them out because there would be no planets in the Goldilocks zone, as was suggested, we might be significantly underestimating the number of possible abodes of life in the universe.
Click to expand...

Oh, in the case of red dwarfs, it's not just the Goldilocks effect. Those stars are magnetically unstable and periodically blow up. Any star that's close enough to either be in that zone, or even worse, tidal locked enough to be heated by the same effect as Jupiter's moons (which actually means even closer), would get its atmosphere blown clean off and surface scorched before it even got to evolve life.

That's a fairly recent tidbit that took everyone by surprise as they watched Alpha Centauri do just that. Previously it was thought that red dwarfs were THE ideal plants to survive around in the future, since they'll last for hundreds of billions of years, long after all other suns have up and died. Turns out that, yeah, no, they have massive periodic explosions that make their planets utterly bare pieces of rock.
 
sphenisc said:
How do you get from no plate tectonics => not much rotation of the core?
Click to expand...

Because it's the accepted theory for why Venus ended up without a magnetic field and most hydrogen or any oxygen not bound to carbon atoms blown away?

Not that it would matter all that much either way, once most of your atmosphere is frozen solid anyway. Like even if you still had a magnetic field, having a few millibars of atmosphere left, and layers of frozen gasses like on Pluto below, would not exactly support life. Is all I'm saying.
 
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HansMustermann said:
Oh, in the case of red dwarfs, it's not just the Goldilocks effect. Those stars are magnetically unstable and periodically blow up. Any star that's close enough to either be in that zone, or even worse, tidal locked enough to be heated by the same effect as Jupiter's moons (which actually means even closer), would get its atmosphere blown clean off and surface scorched before it even got to evolve life.

That's a fairly recent tidbit that took everyone by surprise as they watched Alpha Centauri do just that. Previously it was thought that red dwarfs were THE ideal plants to survive around in the future, since they'll last for hundreds of billions of years, long after all other suns have up and died. Turns out that, yeah, no, they have massive periodic explosions that make their planets utterly bare pieces of rock.
Click to expand...

That particular tidbit is new to me.

Would moons like the ones in our solar system that might potentially have life, i.e. that circle gas giants a long way out from the star, be as badly affected?
 
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