If Earth’s gravity doubled, it would have a variety of negative effects on humanity. Bridges, designed to only hold up a certain amount, would collapse and fall! Cars would no longer be able to draw fuel from their tanks and would stop in a few seconds. Breathing would feel difficult and tiring, and birds would plummet from the sky. Fish and insects, however, would truly flourish, benefitting from the absence of human life, and being small, would be unaffected. Humans, however, would only last a few months or years as bones would slowly bend and eventually snap. The heart would not be able to move the blood for a long time as the blood’s weight would have doubled.
If Earth’s gravity doubled, it would have a variety of negative effects on humanity. Bridges, designed to only hold up a certain amount, would collapse and fall! Cars would no longer be able to draw fuel from their tanks and would stop in a few seconds. Breathing would feel difficult and tiring, and birds would plummet from the sky. Fish and insects, however, would truly flourish, benefitting from the absence of human life, and being small, would be unaffected. Humans, however, would only last a few months or years as bones would slowly bend and eventually snap. The heart would not be able to move the blood for a long time as the blood’s weight would have doubled.
How could birds evolve and what trade-offs would it create?
Birds living underwater would have to completely change their metabolism to suit their new submarine environment. The birds would need to be able to overcome significant challenges like a new respiratory system and no feathers to be able to ‘fly’/move. However, longer wings may be able to generate more thrust, but it would require more energy to move in water.
Birds living underwater would have to completely change their metabolism to suit their new submarine environment. The birds would need to be able to overcome significant challenges like a new respiratory system and no feathers to be able to ‘fly’/move. However, longer wings may be able to generate more thrust, but it would require more energy to move in water.
Birds would suffer the most from this catastrophic event as the change in weight would cause them to plummet before the pressure rose. The moment the gravity doubled, the extra weight would cause them to fall before the air could be thick enough for them to fly in this new environment. Then, air pressure would rise, and having hearts and lungs, would have various illnesses and would succumb to fate. However, if the birds had time to evolve, these would be some of the possible adaptations they could achieve: extended wingspan to cope in the high gravity environment, less feathers on the body to make the birds lighter, a different respiratory system to breath the high-pressure air, and possible be able to ‘fly’ underwater instead.
What would happen to the moon?
The moon would also be affected, but the change would not be instant. Slowly, it would speed up and descend downwards. First the change would not be noticeable, but after a while, it would speed up visibly and appear to be closer, but still, other than flooding at the coastal areas due to extra high tides, there would have no impact. Then the moon would get close enough that it would pass its Roche Limit and break up, burning up in the atmosphere and releasing toxic compounds like SO₂ (which mixed with water causes acid rain) and silica compounds which could cause diseases like pneumonoultramicroscopicsilicovolcanoconiosis. Whew! The rise in temperature would cause a global firestorm and increase the climate crisis by orders of magnitude. Once the material had settled, a post-apocalyptic scene would appear: huge craters, burnt forests, and mounds of rubble. Only a few organisms (like tardigrades) would be able to survive.
What about insects?
Invertebrate insects would have the largest chance of survival as they are lightweight and can easily hold twice their weight. They lack a conventional respiratory system, and instead breathe through pores in their skin. They also don’t have heart, lungs or any delicate organs that could be damaged by it. Ant mounds would collapse, but they would soon figure out a solution. Most insects’ strength-to-weight ratio is higher than humans’. Also, there are more insects than humans, and an insect can reproduce more, meaning that there would be more redundancy.
Write more please, this was good.
Also what would happen to the trees?
Good Question, Areg! What do you think would happen to trees? I will also write my ideas, but I am keen to hear your thoughts!
I think the branches would snap and fall off. Also maybe the leaves would fall off? Would it stop growing? And flatten?
Very Good Hypothesis! I think trees would have difficulty moving up water and nutrients through their trunks, and because they would have pores on their leaves, the high pressure air would cause destruction in them. Also, as you said, the trees would be in danger of falling and compressing under the extra load. However, over a long time, trees would be able to evolve to survive this high pressure and gravity environment by having smaller pores on the leaves, and a higher content of lignin (a protein that appeared a long time ago enabling trees and plants to be taller than a few centimetres) to make them more rigid and able to cope. A larger root system would be helpful, and maybe less dense leaves and branches to minimise weight. Overall, trees would have a chance of surviving, as they are quite hardy, but there would still be a risk of extinction.
I really enjoyed reading these articles. Science is so much more about asking questions rather than providing answers, and your blog reflects that very nicely!
I had a question for how birds would evolve under water. Penguins spend a fair amount of time under water already, are there adaptions that they have made to this lifestyle?
Good Question!
I don’t know much about penguins, but I think they are well adapted to their environment in many ways. Penguins, unlike birds, which have hollow bones, could have ones that are completely (or at least more than bird bones) solid, which could help deal with the pressure and reduces buoyancy. Also, their blood probably contain larger concentrations of oxygen carrying chemicals, which could help them stay under water for prolonged periods of time. They are covered in tiny feathers that trap air which helps them stay streamlined and warm. Penguins lack the traditional feet of birds, and instead, use large flippers, which compromises the ability to effectively move over land. They are also flightless birds and catch their prey underwater, as in the inhospitable places where most penguins live, flight would not be a prominent asset. Thank you for your wonderful comment! I wonder if they could evolve quickly enough to survive completely underwater as global warming may cause their habitats to vanish.
Doubling the gravity would indeed bring its problems and to be honest, sounds like hard work . Halving gravity sounds like it might be nice and may life easier? The bridges would be twice as strong as they need to be, the birds (and us for that matter) would use much less energy getting around. What would your main concerns for us as humans if we woke up tomorrow with half the gravity we have today? Should I be wishing for it as I go to sleep this evening.
Half-gravity may seem like utopian world, but it would disrupt quite a few important things. First of all, pendulums on clocks may be disrupted by the change, and there could be higher concentrations of chemicals in the head that usually aren’t present (see section 3 on my article ‘Tardigrades, Antifreeze and MOXIE: Could a Living Organism Survive on Mars). Mass dampers, huge metal balls used to stabilise buildings during earthquakes would become less effective, and the atmosphere would become thinner due to the minimal gravity holding it back. We would grow faster, potentially risking bone deformations and loss of bone density. However, there would be quite a few positives as well, and aside from the obvious one of it being able to move around with less effort, like the fact that aeroplanes would consume less fuel, making them more efficient. Thank you for you wonderful comment (I hope you sleep well tonight)!