Thanks Wat, that actually takes in a few side topics also, like reducing meat consumption, stopping habitat loss and the current mass extinction, lowering air and light pollution, etc.

60 Minutes had an excellent piece tonight about brain changes in people born from 1995 onwards (the iGen) because of excessive usage of smart phones and ipads and how engineers have admitted that the big tech companies are specifically making apps and devices that would be addictive for children (even toddlers)- similar to fast food-, the NIH is currently conducting a long term study and the early results seem to bear this out.  MRI exams of kids using devices for 2 or more hours a day show changes in brain structure.  

https://www.cbsnews.com/news/phones-tab ... 0-minutes/







https://www.cbs.com/shows/60_minutes/vi ... eedo-green

This is awesome.

[youtube]ds0cmAV-Yek[/youtube]

devices that would be addictive for children (even toddlers)- similar to fast food-, the NIH is currently conducting a long term study and the early results seem to bear this out.  MRI exams of kids using devices for 2 or more hours a day show changes in brain structure.  

I'm getting flashbacks from the eighties when the tobacco companies were willing to admit that cigarettes cause respiratory diseases including multiple types of cancers. Not really a perfect analog here, and of course lots of people still smoke, so....

devices that would be addictive for children (even toddlers)- similar to fast food-, the NIH is currently conducting a long term study and the early results seem to bear this out.  MRI exams of kids using devices for 2 or more hours a day show changes in brain structure.  

I'm getting flashbacks from the eighties when the tobacco companies were willing to admit that cigarettes cause respiratory diseases including multiple types of cancers. Not really a perfect analog here, and of course lots of people still smoke, so....

Yep and before that they used to say there was no connection between tobacco and cancer.
I think people will just do something if they really want to do it, although much less people smoke than the amount that used to.  Also, I noticed there are less people who wear smoke and wear fur in movies too.  Back then everyone was doing  a lot of both!

A-L-E-X wrote:
Thanks!  I remember reading articles about photosynthetic compounds on certain planets could be different colors, like purple, pink, blue or violet, it would be fun to see plants of that color implemented in the program!  We already have plants of those colors on earth, but they are predominantly green (because green is the middle of the spectrum?)

Space Engine does support different-colored flora in its 2d decal databases as per planet type and star-spectral type. As such, terrestrial planets with life that orbit dimmer type-M dwarfs (generally those below type M3V, including brown dwarfs) observably have purple plant-growth. Yellow plant growth is also present on many hot, high-mass terras. If I had SE installed on my computer, I would show you with screenshots, but there are many fine examples here on the forum and SE website. 

As for why our plants here on Earth are green, it is because all plants use the porphyrin-cell pigment chlorophyll with a magnesium atom to absorb blue and red light from the sun. Other light like the green wavelength is reflected, giving the plant a green hue. On Earth this is the only way plants have gathered energy for the carbon-cycle, but there are many alternatives, from using another element atom in chlorophyll (like zinc), to using an alternative to porphyrin cells.

I could explain this in more detail, as well as outline alternative autotroph biochemistry, but I must now be going for dinner. Robert A. Freitas explains it for here.

Its been speculated that adding a powerful enough magnetic field generator in Mars L1 point could create a magnetic tail long enough to protect any atmosphere on Mars.

1) How powerful would this generator and its field need to be for most of Mars to be in a 0.5 to 1.0 Gauss range? (Similar to Earth's, right?)

2) What would be the logistics of such an endeavor?

3) Can this be done with current technologies? And what might the object itself look like?

4) Given Mars' current natural processes and environment, would the atmosphere start to build itself up, given the above Gauss range? If so, how fast and by how much, and/or leveling out at what surface pressure? And would the composition change or be roughly the same?

Before diving into these questions let's go over a little physical background.  A common belief is that Mars lost its atmosphere either because it was not massive enough to hold on to it (and thus thermal escape dominated), or that it was stripped away by solar wind.  

The reality is that Mars lost its atmosphere by a mixture of these and other processes all acting together.  Mars is light enough for hydrogen and helium to readily escape thermally.  This combined with photodissociation of water also explains why Mars is so red.  The Sun's ultraviolet let dissociated the water into hydrogen and oxygen, and the hydrogen escaped while the oxygen reacted with the rocks to form iron oxides.

Another important mechanism for the loss of the Martian atmosphere was impact erosion.  In the early solar system, impacts were big and frequent enough to eject significant portions of the atmosphere to space.

Finally there is sputtering by solar wind directly impacting the atmosphere, which a magnetic field would help reduce.  A planetary magnetic field does not completely prevent this loss however, since near the poles the magnetic field lines do not close around on themselves, so accelerated ions can flow along them and escape into space, producing a "polar wind".  This is an important mechanism for the loss of hydrogen and helium from Earth.

There are still other escape mechanisms for atmospheres, but for Mars these are the big ones.  With this in mind, let's look ahead to this idea of protecting Mars with a magnetic field generated remotely: 

1) How powerful would this generator and its field need to be for most of Mars to be in a 0.5 to 1.0 Gauss range? (Similar to Earth's, right?)

All magnetic fields essentially arise from currents, or moving charges.  For starters, let's imagine the magnetic field generator to be a simple current loop.  The magnetic field along the axis of a current loop is given by



At large distances perpendicular to that axis, the magnetic field is roughly half as strong, so for our purposes the exact geometry of the field is fairly irrelevant to an order of magnitude calculation.

How far must this magnetic field reach in order to protect Mars?  The Martian L1 Lagrange point lies about .0072AU (1.08 million km) in the direction of the Sun:

[center][/center]

[left]Going back to the formula and rearranging it to be slightly more convenient (and dropping a factor of 2 to get the long range equatorial field strength), we can find the amount of current needed in a loop of radius R to cause a field of strength B at a distance z, which we'll set to 0.0072AU.[/left]

[left][/left]

At large distances (z>>R), the required current to produce a field B is proportional to B/R².  So a larger ring is better to minimize the current needed.  

How much current?  Oh boy...  If the ring at L1 is 1000km across, then we need a current of about 10¹⁸ Amps, to enclose Mars in a 1 Gauss field. 

2) What would be the logistics of such an endeavor?

Problem:  10¹⁸ Amps is a lot of current.  

Now I have not accounted for the fact that the solar wind will distort the shape of the field, as you mentioned, so perhaps this reduces the requirements a little.  But computing that effect is complicated, and I don't think it would change the answer enough to matter anyway.  Perhaps this also raises the question, "How do planets generate such wide fields?"  The answer is that planets are very big, so the actual current density circulating around in them can be quite small.  

So I think the short answer to this question is, "to make a magnetic field like a planet, you basically need something like a planet".  

Exotic objects like neutron stars of course have very strong magnetic fields, but this is because they have much higher current densities.

3) Can this be done with current technologies? And what might the object itself look like?

With today's technology it seems difficult at best.  We would probably need to use a superconducting ring thousands of kilometers in scale.  An even deeper problem is how strong the magnetic field must be close to this generator, if we put it at L1, in order to have the required strength at Mars' location.  Using the 1000km wide ring with 10¹⁸ Amps, the field at 100,000km will exceed 1 Tesla, and close to the ring itself it will exceed 100,000 Tesla!  People, ships, infrastructure, electronic components and so forth anywhere near this thing will need to use very good magnetic shielding.

4) Given Mars' current natural processes and environment, would the atmosphere start to build itself up, given the above Gauss range?

Probably not.  Mars is not outgassing very much anymore.  Its opportunity for building up any appreciable atmosphere was in the past.  

The most significant atmospheric process now is a seasonal variation in the CO2 pressure, as the ice caps sublimate and refreeze.  There are also some trace emissions of methane, but this is in the few parts per billion range, and it quickly gets sequestered again in the rocks.  In general the current Martian atmosphere simply cycles between air and ground, with a slow steady loss to space by the various atmospheric escape mechanisms.  To give Mars any appreciable atmosphere we would need to take more direct measures to build it up.

If we did that, then the loss rate for heavy atoms (nitrogen, oxygen, etc) is slow enough that we wouldn't need to worry too much about protecting it with a magnetic field, at least in the short term.  It could help in the long term (millions to billions of years), though eventually we hit a point where we worry about what the Sun is doing and so forth.

Hmmm. Any way to assist Martian outgassing to give a decent atmosphere within Human timescales? What might be able to be done to achieve that, especially if the end goal is a place to live?

Well, that's an extensive topic for the terraforming of Mars, for which there is a lot of literature with different ideas thrown around.  I can recommend the Red Mars Trilogy by Kim Robinson for a nice sci-fi review of many of those ideas.

Here is a sort of riddle for the forum: If a fossilized simple form of life (prokaryotic or eukaryotic, it doesn't matter for this riddle) was discovered on Mars, why would that be bad news for humans as a species back on Earth?

Additionally, why would it be worse news for us if a fossilized lifeform showing more biological sophistication (a bug, or even a rodent analog) was found?

Here is a sort of riddle for the forum:

 “Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”

― Arthur C. Clarke

The more sophisticated they are the more problems they've solved, perhaps more problems than we've solved, or different kinds of problems we can't solve. That's the upper hand.

~~~


Perpetual motion "machines" from harnessing the infinities of Black Holes and/or Dark Energy.

Could I use the force generated from the gravitational pull of a Black Hole that is pulling on a long string, which goes into and feeds the hole, replacing whatever mass is lost from Hawking Radiation, without the need for it to be infinity strong?

What is the limit of electromagnetic bonding? Can we make a piezoelectric string large enough it wont snap? I guess from our point of view, it never even actually passes over the Event Horizon, so our limit to tensile strength doesn't need to be infinite as well.

I'm also thinking a smaller mass Black Hole would have a stronger pull as you got closer to it's surface area and might be preferable in the case of a normal string. Perhaps creating more energy than it consumes in mass will cause it to evaporate so hot the string turns to plasma., so we will want to control its mass and the rate we feed the string.

This is kinetic energy, the acceleration of the string as it reaches the event horizon. This should not be converted to mass in the Black Hole, but it does balance out with the resistance of the magnet in a turbine engine. Voltage is created using a finite number of windings around a magnet, or a really large one if the pull is slow. Is this mass that leaves the end of the string actually happening in real time? Is the energy actually lost to the dilation of time?

Another method would involve gathering Dark Energy from the expansion of the Universe. Galaxies farther away are changing their velocity compared to us, without actually accelerating from some kind of kinetic energy. Is this also a case where I would need a material that can withstand the forces of stretching? or would it simply power an engine on one end? It would gain power over time until friction (from where?) slowed it down to less than the energy needed to make one. I guess the trade off of losing that matter forever to the void, in exchange for it's Dark Energy keeps the universe in balance.

Electrons have an infinite repelling force but we need infinity energy to get that close, and singularities supposedly exist but we can't observe them. Hopefully, I suppose, we could fine tune these infinities to get to a point we collect HUGE amounts of energy cheaply and easily with the right materials. Even if it is only for a short while with minimal material loss. There's also the rotational energy from a black hole, but we can save that question for later.

Stellarator, I don't think either of those findings would imply that at all.

It sounds like you are referencing the idea of a great filter, but that is a deeply statistical kind of thing involving probabilistic events across a large numbers of planets, while finding evidence of extinct life on Mars is a single data point.  Concluding anything about a great filter from that is a very weak argument.  It would be like claiming what the temperature of a gas is by measuring the speed of one atom in it.  Nobody who understands what temperature means would take it seriously.

Another problem with this argument is that finding fossils on Mars would not mean that all life on Mars is extinct.  All it would show is that life got started on Mars.

The great filter argument often goes like this: Since we've found absolutely no evidence of intelligent life elsewhere in the galaxy or universe, there must be some kind of great filter which makes such intelligent life highly unlikely to evolve or last.  So if life, past or present, on Mars is found, that is bad since it implies that life itself is common and not the great filter.  Therefore the great filter is ahead of us.

Even if we disregard the statistical problems of such an argument, I think it's still flawed.  If life is extremely rare, we still know nothing more about a possible great filter ahead of us.  The argument becomes as valid as arguing that there is an increasing chance of rolling a six of a dice the more times it was not six, since the "bad luck" must have been used up.

Stellarator, I don't think either of those findings would imply that at all.

It sounds like you are referencing the idea of a great filter, but that is a deeply statistical kind of thing involving probabilistic events across a large numbers of planets, while finding evidence of extinct life on Mars is a single data point.  Concluding anything about a great filter from that is a very weak argument.  It would be like claiming what the temperature of a gas is by measuring the speed of one atom in it.  Nobody who understands what temperature means would take it seriously.

Another problem with this argument is that finding fossils on Mars would not mean that all life on Mars is extinct.  All it would show is that life got started on Mars.

What about the opposite sort of conclusion, Wat? Lets say we found any evidence of life at all on Mars or Enceladus or somewhere else in our solar system, would that greatly increase the chances of life elsewhere in the universe (unless it originated from the same source as life on Earth), because what are the chances to have life on two separate bodies in the solar system and not have it anywhere else?