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| Low gravity life | |
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| Topic Started: May 30 2009, 01:05 PM (3,819 Views) | |
| lamna | May 30 2009, 01:05 PM Post #1 |
 
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I have long wondered what would happen to earth life if it had to live in very low gravity. Suppose for some reason humans create ecosystems with very low gravity. Perhaps on Deimos. And that this habitat is maintained for millions of years. What would develop? |
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Living Fossils Fósseis Vibos: Reserva Natural 34 MYH, 4 tonne dinosaur. [flash=500,450] Video Magic! [/flash] | |
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| Pando | Sep 1 2010, 02:09 AM Post #16 |
Obey or I'll send you to the moon
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How exactly would a celestial object expand? Where would it get the extra mass from? (also, same thing goes for the branching universe hypothesis, it's impossible because it needs extra mass which doesn't exist and can't be created by the Laws of Physics) Also, if the Earth did expand then why wasn't the atmosphere lost when the Earth was small? Also, I really don't want this topic to turn into a topic on the Expanding Earth "hypothesis". |
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| Forbiddenparadise64 | Sep 1 2010, 02:35 AM Post #17 |
Adult
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That theory is garbage. The earth can't gain mass out of nowhere, that's a basic law of physics, and continental drift has been proven to be true. The earth has always been of this size and always will be. If anything if earth expanded it's density would decrease, perhaps reducing gravity, and as pando said a smaller world will lose it's atmosphere. |
Prepare for the Future Walking with the future: Allozoic (pts 4-6)http://s1.zetaboards.com/Conceptual_Evolution/topic/3252142/14/#new 
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| Pando | Sep 1 2010, 02:38 AM Post #18 |
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Obey or I'll send you to the moon
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Corrected. Also, what is the minimum size of a planet/moon to keep an atmosphere long enough for life as advanced as Earth to evolve? I know the atmosphere contents matter too. |
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| Holben | Sep 1 2010, 04:02 AM Post #19 |
Rumbo a la Victoria
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So let's quash it now. Although millions of tonnes drop to earth from space, yuo've no idea just how mcuh material we lose to space. It results in mainly net conservation. The earth masses 5.9736 × 10^24 kg, so the accumulated mass dropped on us for all that time is nothign anyway. If 5.9736 × 10^24 kg is one G, think how much we'd have to remove to reduce it appreciably... And distributing mass differently under us will have no appreciable effect either. |
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Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea. "It is the old wound my king. It has never healed." | |
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| shomas | Sep 1 2010, 06:05 AM Post #20 |
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Zygote
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Paleobotanist tell us that it was plant life that put oxygen into the atmosphere. Before then it was heavy with more carbon dioxide then today. If the earth did expand and acquired mass it is not illogical to have had a heavy atmosphere and not loose it with a smaller earth. Such a earth also could support a rapid evoloution of Pterosaurs that grew wing spans a large as 40 feet. It is illogical to have a static earth that in the past had the same gravity with a lower oxygen content then now, yet support animal life many times larger then can be supported today with each class of animals heart and circulatory systems. Scientist still can't explain Pterosaurs flight. But it's easer to explain with a denser atmosphere and less gravity then now requiring much less energy to sustain flight. Reptiles are not known for an ability to sustain large energy expenditures as flight would require of such a large beast as a Pterosaurs with our present gravity. Sequentially remove the see floor by age as is done in the bottom center video Expanding earth theories aside, gravity is one restricting factor in the potential size animals can achieve. Removing gravity in part or completely will reduce or remove one of the major factors that has driven evolutionary selection. For one, gravity contributes to bone density and muscle mass by stressing them. Animals will not need to expend as much energy to move about to hunt or forage, and be able to utilize that energy for other means. I believe large size is likely to give an advantage in natural selection when the fitness disadvantage large size presents because of gravity is removed. Edited by shomas, Sep 1 2010, 06:19 AM.
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| Forbiddenparadise64 | Sep 1 2010, 09:27 AM Post #21 |
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Adult
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Actually it is known that oxygen levels have been much higher than todays in the past, such as the Carboniferous and Cretaceous, which can easily explain the size of arthropoda and pterosaurs in the past. The Earth CANNOT gain mass out of nowhere that's a basic law of nature. Besides scientists no longer think pterosaurs grew to 12 wingspans and that 10-11 was the max. Besides the largest pterosaurs were around at the end of the Mesozoic, not the begginning as the expanding earth theory would suggest. The theory contradicts itself as it said Earth's early atmosphere was much denser due to being heavier than today, which contradicts the idea that Earth was smaller with lower gravity than today, that would mean the Earth would have lost it's atmospherev long ago. Besides the biggest animal ever is still alive today, and there is no evidence prehistoric trees grew bigger than redwoods. The expansion scenario is yet another crazy outdated theory made by a bunch of outdated denialist nutjobs, just like the flat Earth society. |
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Prepare for the Future Walking with the future: Allozoic (pts 4-6)http://s1.zetaboards.com/Conceptual_Evolution/topic/3252142/14/#new
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| Pando | Sep 1 2010, 11:57 AM Post #22 |
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Obey or I'll send you to the moon
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^ I see absolutely NO way the Earth could expand. And NO, it does not solve a lot of problems. What about Argentavis? It lived very recently AND IT WAS A BIRD! meaning that it had weaker flight than pterosaurs. Yet it could fly with a 20 foot wingspan even if it didn't fly much. It lived 6 million years ago. Now tell me that pterosaurs couldn't fly in Earth's gravity with their superior flight system. |
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| T.Neo | Sep 1 2010, 12:03 PM Post #23 |
Translunar injection: TLI
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Yeah, the expanding Earth theory is complete nonsense. I mean, let's say... Earth has increased in size 200% in 500 million years... that's a mass increase of 796.8%. Or 0.87 current Earth masses being added to the Earth (5.226e24 kilograms). Over a period of 500 million years, that is 1.045e16 kilograms per year. Assuming it's via a single event each year, that's more than a Deimos mass hitting the Earth each year. Assuming it's a constant influx, that's 3.314e8 kilograms (or 331400 tons) hitting the Earth every second. With the constant influx, that would be a power influx of 66.28 petawatts assuming a velocity of 20 km/s for the particles. At Earth's current surface area, this energy influx would push the global average temperature above 200 degrees. With a smaller surface area, the temperature would be far higher. No organisms of the sort of dinosaurs could survive either an "event per year" or a constant influx of that magnitude. And the idea that this leads to the creation of new ocean crust material or whatever is completely bogus since it would simply bury the current landforms. Some have suggested some wacky mechanism within the Earth that produces more matter... pair production and whatnot don't work that way. You cannot get matter from nothing. And those biological explanations don't make sense either... dinosaurs could have easily gotten that big in our own gravity, though the larger ones were helped massively by the fact that their bones were hollow and supported a network of air-sacs, leading their mass to be much lower than a mammal or reptile of a similar size. As for the original topic... Deimos is too small and the gravity too low. The animals would either die of muscoskeletal atrophy or fail to reproduce properly. The Moon, Mars or Ceres or perhaps even some of the outer planet moons would be a better target for such an experiment. Mars especially, since it's the center of a lot of discussions relating to colonisation and terraforming. |
| A hard mathematical figure provides a sort of enlightenment to one's understanding of an idea that is never matched by mere guesswork. | |
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| Holben | Sep 1 2010, 01:38 PM Post #24 |
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Rumbo a la Victoria
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Unless the animals were mainly exoskeleton, with the juicy bits small and spaced out. But movement would be difficult, and maximum size is about that of a flea. |
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Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea. "It is the old wound my king. It has never healed." | |
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| T.Neo | Sep 1 2010, 02:03 PM Post #25 |
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Translunar injection: TLI
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That depends. I've never heard of microgravity biology experiments being done with arthropods. |
| A hard mathematical figure provides a sort of enlightenment to one's understanding of an idea that is never matched by mere guesswork. | |
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| Holben | Sep 1 2010, 02:05 PM Post #26 |
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Rumbo a la Victoria
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I know they've sent them up, spiders for sure, but i'll have to fidn the details. |
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Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea. "It is the old wound my king. It has never healed." | |
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| Toad of Spades | Sep 1 2010, 02:19 PM Post #27 |
Clorothod
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You're missing one crucial point, Pterosaurs were highly active endotherms. How many reptiles today have a heat retaining body covering and a warm blooded metabolism? None. Just because they are considered reptiles doesn't mean that they should be lumped together with modern reptiles. Pterosaurs are vastly different even though they are still considered "reptiles". They also have tons of specializations for flight. They have hollow bones, a complex airsac system, stiffening wing fibers, and specialized brains to control the large surface area of their wings. They are just as specialized for flight as birds, and would do just fine flying today. The fact that they are still considered reptiles is rather strange to me. Maybe one day they will get their own class separate from reptiles. Edited by Toad of Spades, Sep 1 2010, 02:33 PM.
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Sorry Link, I don't give credit. Come back when you're a little...MMMMMM...Richer. Bread is an animal and humans are %90 aluminum. | |
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| Pando | Sep 1 2010, 02:44 PM Post #28 |
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Obey or I'll send you to the moon
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If they should then they should also be grouped with dinosaurs. Back on topic please? |
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| Toad of Spades | Sep 1 2010, 02:58 PM Post #29 |
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Clorothod
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Okay. How big would a planet have to be in order to have low gravity as well as a thick, stable atmosphere that won't be easily lost? |
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Sorry Link, I don't give credit. Come back when you're a little...MMMMMM...Richer. Bread is an animal and humans are %90 aluminum. | |
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| Holben | Sep 1 2010, 03:01 PM Post #30 |
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Rumbo a la Victoria
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For that, you really want a low density super-earth, which isn't hard. |
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Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea. "It is the old wound my king. It has never healed." | |
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