For Questions That Don't Merit Their Own Thread

[SOXBLOX]

Couple of MDA Gulfstream jets in the air not too long ago, plus something near the pad. These guys think it's a mobile launcher...

https://www.thedrive.com/the-war-zone/mysterious-launch-out-of-cape-canaveral-appears-imminent

[SOXBLOX]

Update to the above article quotes the DoD saying it was to be a hypersonic weapons test, but was canceled due to something in the pre-flight checks. Associated with the LRHW program for the Army. 

[SunlitZelkova]

4 hours ago, SOXBLOX said:

Associated with the LRHW program for the Army. 

This was my guess 

[DDE]

Can you really pour liquid from a very tall vessel into a smaller one? Wouldn't the velocity make it nearly impossible to measure offthe smaller portions?

Inspired by this 1901 for a... walking stick. With an integrated shot glass 

The ad doesn't mention tap water as an option for contents...

[kerbiloid]

In any Caucasus shop for tourists.

Spoiler

 

[AckSed]

3 hours ago, DDE said:

Can you really pour liquid from a very tall vessel into a smaller one? Wouldn't the velocity make it nearly impossible to measure off the smaller portions?

It is not wholly silly, just mostly silly, as I think spirits have a lower viscosity. Besides, if I was designing a walking stick as a tot flask, I'd have a stopper with a smaller hole for pouring, which, by the size of the stream, this might have.

[magnemoe]

2 hours ago, AckSed said:

It is not wholly silly, just mostly silly, as I think spirits have a lower viscosity. Besides, if I was designing a walking stick as a tot flask, I'd have a stopper with a smaller hole for pouring, which, by the size of the stream, this might have.

Agree, having an large opening would not work that well as OP pointed out. If smart design you have an double stopper with an small hole fully closed its closed, turn faction of an turn and the small hole is open, screw more to remove the stopper to refill or if you want to poor content back into an bottle. 

[kerbiloid]

Non-shaking hands are required, to tilt it carefully.

[tater]

 

[AckSed]

At Venus temperatures, how much softer is volcanic rock after it cools? On the one hand, there's no water to hydrate minerals. On the other hand, being immersed in a sea of supercritical CO2 has to do something.

[magnemoe]

1 hour ago, AckSed said:

At Venus temperatures, how much softer is volcanic rock after it cools? On the one hand, there's no water to hydrate minerals. On the other hand, being immersed in a sea of supercritical CO2 has to do something.

Not much I think but Venus is weird as it don't have plate tectonic, rater it looks like something like the Siberian trap become very common every some hundred million years. 
And yes that was the event  250 million years ago who was much more devastating than the asteroid who killed the dinosaurs. 
So this being much stronger is very bad. 
The thick atmosphere, the slow rotation, the lack of water? 
An expensive question, in telescopes  

[Jacke]

38 minutes ago, magnemoe said:

Not much I think but Venus is weird as it don't have plate tectonic, rater it looks like something like the Siberian trap become very common every some hundred million years.

And yes that was the event  250 million years ago who was much more devastating than the asteroid who killed the dinosaurs. 

A recent video on the Permian-Triassic Extinction.  Currently now thought to be a linked triple event.  Outside of this video, I've heard that like the drier climate of the Permian, the Large Igneous Province, the Siberian Traps, was spurred on by the forming of the continents into one land mass, Pangaea.  Must have been other factors, as previous supercontinents hadn't caused this much vulcanism.  At least Large Igneous Provinces don't show up overnight but give lots of warning, as they make even supervolcanoes look like popguns.

Spoiler

 

There's also some information on when plate tectonics started on Earth.  It does seem to have been a big driving force in making Earth different.  Linked to the presence of surface water which then permeates down to the bottom of the lithosphere, the bottom of the tectonic plates.  And in helping drive the carbon cycle, seems to help keep Earth mostly close to the amount of carbon dioxide to counteract the Main Sequence Brightening of the Sun.

Spoiler

 

 

38 minutes ago, magnemoe said:

So this being much stronger is very bad.

The thick atmosphere, the slow rotation, the lack of water? 

An expensive question, in telescopes  

The slow rotation of Venus seems to have been original.  I've not heard it recently but I have heard that Venus's rotation is actually coupled to Earth such that the same side of Venus faces the Earth at its closest approach at inferior conjunction.

If there was any plate tectonics on Venus, the heating of the atmosphere, destroying any atmospheric cold trap (which on Earth keeps water vapour well below the ozone layer and relatively protected from solar UV light) and leading to the loss of its surface water likely ended plate movement long ago.  Rising temperatures and loss of water drove the carbon dioxide out of the rocks forming a thick atmosphere.

It's really really hard to study Venus as the surface conditions destroy any probes in short order.  Outside of remote sensing from orbit, there's a lot of R&D going on to develop more rugged components for landers for the future.

[kerbiloid]

Afair, the Venus doesn't have a Moon, so it was never partially melted inside by the rapid unplanned interaction, while the Earth was.

Thus, the process of core extraction on in the (semi-liquid inside) Earth was running much faster, and a huge plume of lightweight original minerals was pushed out from the iron bubble, which was forming the future core.

The alumosilicate plume reached the surface and formed a lightweight continental flatbread, floating on denser minerals of the mantle.
(Not wjere it had raised up, but at the opposite point of the Earth, where the geological tsunami was stopped by itself and stayed calm).

Thus, the Earth is quickly rotating in a random direction caused by the proto-Moon trajectory and further tidal smoothing, it has continental platforms (remains of the original flatbread), an active core which causes a magnetosphere, and the Moon.

While Venus keeps its original rotation, slow and in initial direction.
The protoplanetary pieces on the orbits below are moving faster than the planet and giving momentum it in the orbit directon, while the pieces on higher orbits are moving slower, get caught by the planet and give its upper part a counter-orbutal momentum, thus both make the finally formed planet rotate slow and in the Venusian direction. Later the tidal forces adjust this.
The Venus rotation couldn't be caused by the Earth or the Sun gravity, because the Earth rotation wasn't.

As Venus was not disturbed by some large proto-moon, and thus was not quickly softened inside, its core extraction was running much slower and calmer, thus no  powerful  continental plume had appeared at once, and it doesn't have continental platforms comparable to the Earth, only cracks (tesseras) caused by cooling.
Also, that's why it doesn't have an active core and a magnetosphere.
Several  hundred million years ago the gravitational differentiation reached the point when finally large amounts of lithophylic minerals reached the surface and caussed mass volcanism, having digested the original Venusian surface.
Now we can find random aftershocks of the finished volcanism.

[JoeSchmuckatelli]

On 3/15/2023 at 6:29 AM, DDE said:

Can you really pour liquid from a very tall vessel into a smaller one? Wouldn't the velocity make it nearly impossible to measure offthe smaller portions?

Inspired by this 1901 for a... walking stick. With an integrated shot glass 

The ad doesn't mention tap water as an option for contents...

Weren't most European taps of the era fed by lead pipes?

Very forward thinking and health conscious if you ask me. 

[SunlitZelkova]

Previously I asked if it was possible for the Mars with a thick atmosphere allowing gliding landers imagined by engineers prior to Mariner 4's visit to the planet in 1965 to come to life, and received an excellent answer from sevenperforce.

On 12/10/2022 at 10:06 PM, sevenperforce said:

Oh, that's certainly possible. The atmosphere of Mars was much denser in the past, but due to the planet's smaller size and lack of a magnetic field, most of the water vapor that was once in the atmosphere escaped into space.

If the polar icecaps on Mars were to melt, they would roughly double the density of the Martian atmosphere, which would cause accelerated greenhouse warming, which would cause sublimation of gases currently adsorbed by the soil, which would really start to crank up the density of the atmosphere. If you're looking at the past, then you could envision a situation where Mars was struck by a particularly large comet a few million years ago. That would probably be enough to do the trick.

So this brings me to a new question, also related to a story I plan to write- what would have needed to happen to Venus for it to be capable of harboring Earth life, i.e., true to it's moniker of "Earth's twin"?

I can't remember where I read it, but apparently prior to Mariner 2's visit in 1962, it was theorized by some that Venus might have dinosaur like life beneath its cloudy skies. I want to create a world where that was true, perhaps also related to the idea that life came to Earth via panspermia from Venus. Could circumstances have been different to where such a situation was realistically possible, or would I need to handwave it?

I'm glad the timing of when I asked this question worked out with the new Venus discovery.

[Jacke]

1 hour ago, SunlitZelkova said:

Previously I asked if it was possible for the Mars with a thick atmosphere allowing gliding landers imagined by engineers prior to Mariner 4's visit to the planet in 1965 to come to life, and received an excellent answer from sevenperforce.

So this brings me to a new question, also related to a story I plan to write- what would have needed to happen to Venus for it to be capable of harboring Earth life, i.e., true to it's moniker of "Earth's twin"?

I can't remember where I read it, but apparently prior to Mariner 2's visit in 1962, it was theorized by some that Venus might have dinosaur like life beneath its cloudy skies. I want to create a world where that was true, perhaps also related to the idea that life came to Earth via panspermia from Venus. Could circumstances have been different to where such a situation was realistically possible, or would I need to handwave it?

I'm glad the timing of when I asked this question worked out with the new Venus discovery.

It doesn't matter what was imagined about Venus and Mars before there was enough data on what really was going on there.  I think Venus was doomed because it was so close to the Sun, just as Mars was doomed by being so small.  Venus may also have been doomed by rotating so slowly; this one is more tricky as it's uncertain what the history of its rotation has been, as is known to a large degree for Earth.

Venus being closer to the Sun was hotter than Earth.  That led to it lacking or losing the things that protect Earth and its atmosphere.  Even at a small amount of oxygen in the atmosphere leads to an ozone layer that shields the atmosphere below from most hard UV light.  The way the atmosphere becomes structured means that there's a cold trap in the atmosphere that removes virtually all water vapour above about ~11km, well below the ozone layer.  Together they protect the water vapour in the atmosphere from being broken down into hydrogen and oxygen, of which the hydrogen is easily lost to space.  On Venus, that likely led to it losing most of its water vapour leading to the atmosphere heating up higher, even to plate tectonics if it had been established to stopping as its lithosphere also dried out.  The higher temperature also drove carbon dioxide out of the rocks leading to an even thicker atmosphere and even higher temperatures.

Venus's slow rotation likely means it never had a very strong magnetic field, even in the past.  Mars has a similar problem, but it's due to it being smaller, which led to its core cooling sooner than the Earth's, leading Mars to lose any magnetic field it did have in the past.  Without a strong magnetic field, both Venus and Mars's atmospheres are exposed to the Solar wind from the Sun.  For the smaller Mars, this means what atmosphere it has was significantly eroded by the impact of the Solar wind.  Earth has its stronger magnetic field except during field reversals, about every few 100,000 years.  Earth's surface is protected from Solar wind radiation by the thicker atmosphere during reversals.  Mars is exposed to this all the time.

[kerbiloid]

On 3/17/2023 at 2:39 AM, SunlitZelkova said:

what would have needed to happen to Venus for it to be capable of harboring Earth life, i.e., true to it's moniker of "Earth's twin"?

Bring a lot of water, as probably the Venusian minerals are totally dehydrated and can't form a hydrosphere of any kind.

Return carbon from CO2 onto ground and bind it into soil.
As elementary carbon is chemically inert, this means that you have to bring a lot of chemical compound reacting with CO2 (like the air regeneration systems do).
Or you can trying this with bacteria, but there is an unexpected problem: bacteria love water. So, the less water you have, the fewer bacteria you can herd, the lower is the bacterial concentration, the slower is their reproduction.
In the Earth ocean it took a billion years or so to bring first results. So, the bacterial way looks as viable as the Venusian dinosaurs are.

To get the alcali oxides, you should extract them somewhere where they are. Outside of Venus, as the local alcali are already there and thus splitting the local carbonates would also bring additional CO2.
So, probably you need some gypsum to extract CaO and O, condense S, and bind CO2 with CaO. Probably, there is a lot of gypsum on Venus, as it definitely doesn't suffer from absence of sulfur.

Thus, you should bring comets and snow them; split gypsum and bind CO2 into the limestone, use the lime to cover large areas to make Venus blinding-white and reflect the solar light more effectively, and form oases in artificial valleys, form water channels for heat exchange between the long-day and long-night hemispheres.

Before that you should form a stable cloud of dust between the Sun and the Venus, to absorb the solar wind and UV, as there is still no magnetosphere.
The cloud should be placed at Lagrange point.
The dust should have high molecular mass to be stable, thus it's some kind of minerals, maybe remains of the comets which brought water.

 

On 3/17/2023 at 2:39 AM, SunlitZelkova said:

I can't remember where I read it, but apparently prior to Mariner 2's visit in 1962, it was theorized by some that Venus might have dinosaur like life beneath its cloudy skies

https://fr.wikipedia.org/wiki/Camille_Flammarion

Les Habitants de L'Autre Monde

***

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

Spoiler

 

***

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

Spoiler

 

Edited March 18, 2023 by kerbiloid

[DDE]

11 hours ago, SunlitZelkova said:

I can't remember where I read it, but apparently prior to Mariner 2's visit in 1962, it was theorized by some that Venus might have dinosaur like life beneath its cloudy skies.

Wikipedia is a bit of a mess in that it's solit this information into pages on history of studies and history of cultural depiction. To give you the cliffnotes version, Venus was usually viewed as either a tropical/swamp world, an ocean world or a desert world. There was some appreciation of the greenhouse effect - Svante Arrhenius himself, the guy behind the discovery, backed the "swamp world" theory for Venus - and there was the conjecture that the unbroken cover of what back then were assumed to be water vapor clouds meant the planet lacked heterogeneous surface features like continents (and, therefore, was from sci-fi). Dinosaurs come from another contemporary conjecture - that the planets cooled down and formed from the protoplanetary disk from the outwards in.

Going back to your question, I think Venus gravely needed water, which would've facilitated the sequestering of carbon, and possibly enabled plate tectonics. This is also likely related to the lack of a major magnetic field... wherein the culprit for the difference with Earth may be Theia and the big slap it gave to early Earth, kickstarting the core dynamo.

https://phys.org/news/2017-12-doesnt-venus-magnetosphere.html

This means you may need to arrange a hit on Venus. Also, goddamn, that's such a serious boost for the Rare Earth Hypothesis...

[JoeSchmuckatelli]

4 hours ago, DDE said:

the Rare Earth Hypothesis..

We certainly have reason to believe we may have won the Galactic Lottery with this wet rock.

I've gotten into this with people before - but I do think our having a moon is significant for plate tectonics, which drives vulcanism and atmospheric cycling.  Similarly, if the moon keeps things churning, this could add to the strength of our magnetic field.  Venus, not having a moon, still has evidence of vulcanism but from what I read the processes are different.  More like Hawaii or Yellowstone than Ring of Fire.  Being more stable - lacking regular tidal stresses - might tamp down on magnetic field generation.

Of course - Endor might be more common.  Ganymede has its own magnetic field, driven by convection and tidal forces.  It's possible a gas giant in the goldilocks zone could have a wet-rock moon.

[kerbiloid]

There is no Earth in the Universe, only Venus.

The Earth is a temporarily paused Venus.

A typical planetary  evolution of the 2nd Venus was set on pause by a random unique event, the rapid unplanned interaction with Proto-Moon.
The smooth planetary evolution diagram got a flat horizontal plateau, where the biological life had time to evolve, we call this damaged Venus "Earth".

[Lisias]

42 minutes ago, kerbiloid said:

There is no Earth in the Universe, only Venus.

The Earth is a temporarily paused Venus.

A typical planetary  evolution of the 2nd Venus was set on pause by a random unique event, the rapid unplanned interaction with Proto-Moon.
The smooth planetary evolution diagram got a flat horizontal plateau, where the biological life had time to evolve, we call this damaged Venus "Earth".

You forgot about a continuously growing event- the Sun.

That thing is getting hotter and hotter as time passes.

In the past, the Sun was dimmer. A lot dimmer, it's brightness at the time Earth was forming was about 70% of what we have now.

When the first monocelular lifeforms happened around here, the Sun was yet about 75% of the current brightness and Earth wasn't a snowball (yet) because the Earth Crust was still too thin and the Mantle's heat kept things warm enough.

By the time the first photosynthesis happened, the Sun probably was shining at 80% of today standards.

In the mean time, Venus could be a Paradisical Planet fit to breed life. Perhaps the lost Eden?

---------

Source.

Edited March 18, 2023 by Lisias
Link to source of information

[kerbiloid]

1 hour ago, Lisias said:

You forgot about a continuously growing event- the Sun.

Sun grows for everyone, and hates everyone equally, both Venus and paused Venus aka Earth.

The "Earth" pause on our planet fits the Sun plateau, when the solar luminosity is more or less stable (80..120% of the curent Sun), before the red giant phase.

[magnemoe]

More of an rant but why are divide by zero that much of an bug in computers. for 8086 cpu's its even an dedicated interrupt. while in 99% of cases there you get x/0 its because its no data getting an average of none attempts and here 0 is a good answer. 
Yes its nice to capture this but still. 

[Terwin]

4 hours ago, magnemoe said:

More of an rant but why are divide by zero that much of an bug in computers. for 8086 cpu's its even an dedicated interrupt. while in 99% of cases there you get x/0 its because its no data getting an average of none attempts and here 0 is a good answer. 
Yes its nice to capture this but still. 

"How many groups do you get if you take away zero at a time from your starting set?"  

Divide by zero is also something of a bug in math, as anything other than 0/0 is nonsensical.  Computers operate on math, so when they try to perform an operation that should produce a nonsensical result, they have a problem because they cannot handle said nonsense.

Computers are also not able to calculate infinity, and any attempt to do so will also result in problems due to limited computation/storage space. 

Division of floating point numbers is also the most difficult and time-consuming operation that computers perform, so optimizing those operations, especially pathological cases, can shorten the cycle time of the processor, allowing for an increase in clock speed. (that MHZ or GHZ number that they list for the CPU or GPU)

 

[K^2]

11 hours ago, magnemoe said:

More of an rant but why are divide by zero that much of an bug in computers. for 8086 cpu's its even an dedicated interrupt. while in 99% of cases there you get x/0 its because its no data getting an average of none attempts and here 0 is a good answer. 
Yes its nice to capture this but still. 

In early 8086 architecture, interrupt wasn't a bug. It's just how the CPU talked to the program. Audio card ready for another packet of data? Interrupt. User pressed a key? Interrupt. Some fixed amount of time passed, as set by the timer registers? Interrupt. Having a divide-by-zero generate an interrupt wasn't seen as a problem. You can literally write a two instruction handler that says "set answer to zero, then resume," and you're done. You get your x/0 = 0 behavior practically for free if you want it, but you can also do something fancier if you needed it. It just wasn't a problem.

And then 80386 happened with its 32 bit addressing only available in the protected mode and over the next decade the interrupts went from something the programmer takes care of to something the operating system takes care of. But the design choice of division by zero always raising an interrupt remained, because that was legacy behavior that had to be maintained. In principle, there was a design choice to be made with all of the modern operating systems to handle that interrupt differently. After all, a key press still generates an interrupt under the hood, but the operating system takes care of it without generating a signal. So we never think of a key press as a bug. But because division by zero is a signal, along with fun things like general protection fault and illegal instructions, they are handled by a programmer in a similar way to a genuine error. Or, if unhandled, will terminate the program.

Was this the correct choice for the operating systems? Hard to say. But given that both Linux and Windows adopted this approach in the early 90s, by now it's basically just a fact of life. If you want to write your own operating system, or even just a kernel mod for Linux, that handles division by zero differently, it's absolutely an option.

This does bring up one more curiosity. Floating point is different. Unlike the integer division by zero, which always raises an interrupt, floating point division by zero may raise an interrupt. There is a CPU flag that controls whether this happens, and it is off by default for any new process, meaning the programmer has to opt-in to receive floating point division by zero as a signal. Otherwise, that division is ignored, and you get either INF or NAN result. This was partially done because on 386 the FPU was originally a co-processor, but I suspect at least in part because it was anticipated that this will happen more often with floating point computations, and an interrupt should absolutely not be the default way to handle this, especially with protected mode enabled.

The ability to set up floating point traps is absolutely amazing for development, and I do wish that more people would know about it. I like to run debug builds with FPU interrupts, because then if I didn't do the correct checks in my collision detection code, for example, and generated an unchecked division by zero, instead of finding out about it after hours of debugging a weird collision glitch, I can simply get an interrupt when it happens. There are, however, some compiler optimizations that come into conflict with this. One that caused me most gray hair back in the day was when Microsoft decided to emit SQRTPS signal for the sqrt() call in SSE-optimized code. So any time you take a square root, there's a chance that some of the unused values in the MMX register are negative, and that will trip an exception handler which is slow! So the fix for it is writing your own sqrt() function that emits SQRTSS and hope it doesn't wreck the optimization. Naturally, it's not a great strategy for production code, but it's good for debug builds. So I still recommend doing this, but it is a bit of a hassle. And don't forget to make sure it's disabled in production.

Edited March 21, 2023 by K^2