Bacteria can grow under extreme gravity: study

For Rocky planets like ours, current thinking is that the larger the planet, the higher chance of plate techtonics (Which helped give early life chemicals it needed) and protective magnetic fields form - With significant supportive experimental evidence for it.

This goes to show that life should be relatively unnaffected by 2-3 g's on these planets...meaning that 'super-earths' are now a very attractive place to look for life.

"...and gives evidence that the theory of panspermia could be possible."

I assure you, a theory of panspermia is quite possible. In fact, entire books have been written about the theory. Let us know when there's some evidence that the theory is true.

I cant see why anyone would have ever thought that bacteria coudnt grow under 10 - 100 g. It just doesnt seem like a logical assumption. 400,000 g is pretty impressive though, and I wouldnt have guessed that one. My question now is what would a multicellular organism look like on a planet with 10 - 100 g?

My question now is what would a multicellular organism look like on a planet with 10 - 100 g?

Flat.

My question now is what would a multicellular organism look like on a planet with 10 - 100 g?

I doubt you would see land based creatures much larger than a small mouse. In all likelyhood most of the creatures would be aquatic, using equilibrium to abate the effects of gravity. But that's just a guess.

Where did the asteroid microbes come from?

The gravity feat is more impressive that the bacteria actually grow and not just survive.

On a side track What is the highest pressure that bacteria can grow in? I believe it is over 1000 atmospheres but is there a known limit?

Hmmm...Mega-gravity on Jupiter,after travelling at space-normal speed or mach 333 for a million years, near absolute zero and in a vacuum, bombarded by everything in the EM spectrum, and no organelles:
ANDROMEDA- no amino acids, no DNA, crystalline life that uses compartments rather than organs for biochemical synthesis. Ooops, Andromeda "...used everything and wasted nothing.." no evident mechanism for adaptive evolution, since instead of mutating it would eat the adaptive trigger, heat, cosmic rays, stray x-rays, etc, and grow forever. Shucks, back to the lab Pinky!
-word-to-ya-muthas-

Say what?

He's referring to the SciFi novel "The Andromeda Strain" by Michael Crichton.

What exactly are "hyperaccelerative conditions"?
Google doesn't seem to know the answer to this one..

Why investigate bacterial growth in a 403,627g environment? "Because it's there"? I expected the article to say something like, "We were trying to see whether bacteria could survive the high-acceleration impact from riding in on a asteroid or comet to a host planet." But what range of decelerations does an exoplanetary body impacting a planet sustain? And wouldn't heat be a bigger threat to destroy any exoplanetary bacteria arriving by impact? This result to me sounds like an answer in search of a research question.

But what range of decelerations does an exoplanetary body impacting a planet sustain?

I don't have figures for that, but a harddrive falling on a stone floor experiences up to 30000g at the moment of impact. Given that a meteorite might be a bit faster than a falling harrdrive I could well believe that the impact accelerations might be an order of magnitude greater.

I can't wait till we find life on exo-planets, maybe then this royal wedding will end.

Does anyone think that aliens sent an impact rock to earth for an experiment to see if life could happen beyond (their) system? Just a dumb question, but you never no. Humans could be some little girls science project gone absurd. What do i know though?

All life forms we have discovered so far is related and can be traced back to a single life form. We have not found any alien life on Earth. This tells us that creating life from nothing is not easy and is very rare. Otherwise we shoud have different examples on earth of life that developed independantly. The conclusion is that life on earth must be of alien origin and the earth was seeded from life that spontaniously generated on some other planet and brought here through the scratering of astroids and comets and related events. To suggest that this planet out of the trillions of planets and dust particles that life can be on, in our galaxy was the only one to generate life spontaniously is only a religion and cannot be based on scientific thought. If life generated spntaniously here and elsewhere then we would have evidence of different unrelated life on earth from the actions of the astroids, comets, and all the churnings going on for the billions of years of our gallaxies existence

I just got a fantastic idea for materials research, unfortunately I'm not sure if we have the technological ability as of yet.

Imagine the structures these bacteria would evolve over time under such high gravity. Very well could discover some novel processes by which one could create biological supermaterials.

Way to bring up the religion card buddy, this is physics

And wouldn't heat be a bigger threat to destroy any exoplanetary bacteria arriving by impact? This result to me sounds like an answer in search of a research question.

Yes, heat is now the biggest hazard to panspermia, especially based on the high g's that we now know that bacteria can handle. However, that question has been worked on too, and if the bacteria have a spot deep enough in the rock, they are protected to the point where it is very viable. In small asteroids (say, less than 10 feet across), they don't need to be very deep at all.

That said, I'm not a proponent of panspermia. I think it's certainly possible in small scale scenerios, but becomes very unlikely outside of a single star system - It is only slightly better than a pure acedemic question - at least it does give us something to look for on asteroids and such.

All life forms we have discovered so far is related and can be traced back to a single life form. We have not found any alien life on Earth. This tells us that creating life from nothing is not easy and is very rare. Otherwise we shoud have different examples on earth of life that developed independantly.

Not really. Life on this planet, i.e. the biosphere is the result of countless years of competition and cooperation. While most early forms of life didn't make it to the present day there were some that became integrated and amalgameted and survived the rest (which might have been quite different). The biology of the first billion years on the local planet is not very well known.

The density yield of molecular compound production might be better from such bacteria.

Not really. Life on this planet, i.e. the biosphere is the result of countless years of competition and cooperation. While most early forms of life didn't make it to the present day there were some that became integrated and amalgameted and survived the rest (which might have been quite different). The biology of the first billion years on the local planet is not very well known.

Couple this with the propesity for horizontal gene transfer in single celled organisms and attempting to find the origin of life on Earth becomes highly complex.

There very well could have been hundreds of starts to life that transferred genetic material to each other resulting in a single ancestor for all of life, without that ancestor being the original life form.

The conclusion is that life on earth must be of alien origin

Right, right, because originating elsewhere averts all the challenges of creating life here and introduces no new challenges.../sarcasm

My question now is what would a multicellular organism look like on a planet with 10 - 100 g?

I doubt you would see land based creatures much larger than a small mouse. In all likelyhood most of the creatures would be aquatic, using equilibrium to abate the effects of gravity. But that's just a guess.

Im picturing something like a groundhog, but with legs proportioned more like a rhinoceros. I picked up a prairie dog once, and was surprised at how stalwart and muscular it was. It tried to burrow under me as I sat on the floor, and was able to wedge itself right under 80% of my mass! Its not a huge stretch for me to imagine a 10 pound rodent like that being redesigned to carry 10 times the weight. It's bones would have to be pretty thick, and it might even have some kind of exoskeleton as well that would support it's organs. Just using my imagination, Id bet that under 10g, dog- sized creatures might be the maximum size reached. Thick, anklyosaur- like dogs.

The largest land animals on our planet were giant sauropods (the largest possibly being 150-200 tons and 200 feet long). A 10g world inhabited with life using earthly biology can then be expected to reach dimensions around 1/2 of that, with masses being around 1/8.

If the organisms on the 10g world are selected for size and use exotic biology, it might be beyond our imagination.

All life forms we have discovered so far is related and can be traced back to a single life form. We have not found any alien life on Earth.

The question is: Did that forst life form originate here? That is as of yet unanswerable. We'll know when we detect life elsewhere.

Otherwise we shoud have different examples on earth of life that developed independantly.

No. Evolution would take care of that pretty quickly if one type is better at gathering resources than any other. Once one type gains enough of a head start in the evolutionary game then it's increasingly unlikely that a 'new start' would provide an alternative that doesn't die out immediately thereafter.

then we would have evidence of different unrelated life on earth from the actions of the astroids, comets,

since we haven't looked at too man of these (and the vast majority of them would be of non-planetary origin or have undergone conditions that would preclude life) that conclusion is a BIT premature.

The largest land animals on our planet were giant sauropods (the largest possibly being 150-200 tons and 200 feet long). A 10g world inhabited with life using earthly biology can then be expected to reach dimensions around 1/2 of that, with masses being around 1/8.

If the organisms on the 10g world are selected for size and use exotic biology, it might be beyond our imagination.

He's got a good point there. I'm sure there is a point where gravity becomes an overriding factor, but based on our own biosphere and history, it seems to indicate that bouancy or thickness of the medium(IE - look at the oceans, and the blue whale) and the oxygen content or analogue (IE look at the dinosaurs sizes) will probably have more effect on animal size than a few G's.

oh, and the largest animal known to have lived is in fact the blue whale

oh, and the largest animal known to have lived is in fact the blue whale

You've just made me realize that I want to see one before I die.

If so then why do we not see different forms of life that have been generated recently? Why can't we get life to arise from non-life in a lab? If the reason all life is the same today is because of evolution and competition then where is the new life? It is much easier to create new life today with all the organic material available to work with than there was billions of years ago.

I conclude that because we cannot find any different kind of life it implies that it is very difficult to create and that it is more likely to have been created elsewhere and gotten here that to have been created here.

If so then why do we not see different forms of life that have been generated recently?

Have you combed the entirety of the surface, atmosphere and terrasphere of the planet each second of each day?

Why can't we get life to arise from non-life in a lab?

We have. We commonly assemble and on occasion "evolve" RNA machines to do autonomic work for us in the lab. We've also created a functional self replicating DNA chain.

If the reason all life is the same today is because of evolution and competition then where is the new life?

Eaten most likely.

It is much easier to create new life today with all the organic material available to work with than there was billions of years ago.

There is no more or less organic material on the planet today than there was previously, beyond that, life need not be constrained to organic molecules.

Why can't we get life to arise from non-life in a lab?

Yes, we can. But the experiment will take at least one milion years.

Why can't we get life to arise from non-life in a lab?

Yes, we can. But the experiment will take at least one milion years.

In theory :-)

In the past, when calculating the maximum size of a tree transplanted on another planet, and assuming wind is similar to earth, but gravity is not, I found that as gravity decreases, the maximum breaking mass of a tree branch increased by a formula related by the power of 1.5. Pruning allows you to get numbers better than 1.5 in the short term, but never better than 2.0. Conversely, if you increase gravity then the maximum breaking mass of the branch decreases by a formula related by the power of 1.5.

Applying this knowledge, and assuming our redwoods are at or very near their upper height and mass limits, then the maximum height of an Earth biology tree on a planet with 10g gravity should be roughly 12 to 13ft before it breaks under it's own weight, assuming otherwise Earth-like conditions and Earth-like winds.

On the other hand, under 0.1g, a tree the size of the Avatar tree should theoretically be possible with earth-like biology and no pruning.

The previous post only considers gravity and hte structural integrity of wood. It disregards other environmental consequences, and also does not consider the energy transport costs of moving water up the tree trunk under extreme gravity, although under lower gravity this should clearly benefit the tree geometrically, it's unclear what the effects would be under heavy gravity, since the maximum height is much lower anyway, as the water doesn't need to be moved as far...

Additionally, for heavy gravity, this does not consider the possibility of "trees" which become much wider than they are tall, and therefore may exceed this maximum height just by becoming some sort of "mound" of tree or tree-like material, although the lower portions of the organism may still become crushed under it's own weight, destroying the cellular life there, so it might not be possible anyway. The tree may become some sort of coral-like structure building mounds on it's own dead cells.

The maximum height of a giraffe or sauropod like organism on an extreme gravity planet would be related by a similar formula, since the organisms tail or especially neck would break under it's own weight according to a very similar formula. Mass goes proportional to cross-sectional area and length. Weight is a consequence of mass and gravity, but since maximum strength of the neck goes up as the area of the cross-section of neck, while mass goes up by the same amount multiplied by length...

Assuming Sauropods are at or very near the maximum size for an animal on Earth. Then the maximum height of an earth-like animal on a 10g planet would be much less than the linear figure of a factor of 10 might suggest. It is again smaller by a factor of around 31, or 10^1.5. Probably around a foot in height, and maybe 1.5 to 3 feet in length head to tail.

Basicly the size of a small cat or dog would be the upper limit, and these would be the "giants" of the planet.

Assuming Sauropods are at or very near the maximum size for an animal on Earth. Then the maximum height of an earth-like animal on a 10g planet would be much less than the linear figure of a factor of 10 might suggest. It is again smaller by a factor of around 31, or 10^1.5. Probably around a foot in height, and maybe 1.5 to 3 feet in length head to tail.

Why wouldn't a sauropod like creature on an 8g world with 1/2 the area and 1/8 the volume be equivalent to the ones we had on earth in terms of structural stability?

Can we stick to facts and not crazy theories of panspermia. Even if aliens existed(though they do not) that would still not answer the question, where everything came from.

Does this mean that we should start searching for life on neutron stars, sterilize our centrifuges or chuck another paper in the trash?

Do the right thing and recycle the paper.

Assuming Sauropods are at or very near the maximum size for an animal on Earth. Then the maximum height of an earth-like animal on a 10g planet would be much less than the linear figure of a factor of 10 might suggest. It is again smaller by a factor of around 31, or 10^1.5. Probably around a foot in height, and maybe 1.5 to 3 feet in length head to tail.

Why wouldn't a sauropod like creature on an 8g world with 1/2 the area and 1/8 the volume be equivalent to the ones we had on earth in terms of structural stability?

The strength of a material does not "scale". At a certain point, adding more bone increases the weight more than it increases the strength.

Wood and bone grow more in total strength as cross sectional area increases, yes, but their strength per unit area remains the same.

So mass (and consequently weight) increases by a cubic function with volume, but the strength of wood or bones increases by a square function with the cross sectional area.

Ok, the logic of how it becomes a power of 1.5 is a bit hard to see, but you have to think about the strength of the structure as it grows.

As long as the breaking weight is greater than the current weight, then there is still theoretical room for growth. As the structure grows, the breaking weight increases because the cross section increases. A tree can only grow taller if it continues to grow thicker.

It's easier to see going from Earth gravity to weaker gravity. If you take a tree that is at it's breaking weight when it's mass equals M, and magically transport it to a moon with 0.1g gravity, then initially, it has room to grow to a mass of 10M. However, by the time it reaches mass 10M, the trunk and primary branches are, on average, 4.64 times as large in cross-section, so therefore they can now support a mass of 46.4M...but by the time the tree gets to mass 46.4M, the trunk and primary branches reach a cross-section even bigger...

The limit of height, H, on the second world ends up being expressed as the reciprocal of gravity in terms of Earth gravity (1/XG), raised to the power 1.5, and then multiplied by the height, h, of the organism on Earth.

h*(1/(Xg))^1.5 = H

The reason for this is life doesn't grow magically. You need time for the cross-section to grow so strength exceeds what the breaking weight will be when the structure is completely grown.

All of this pseudo-science math gives me a headache.