Score
Title
263
AskScience Panel of Scientists XVIII
628
AskScience AMA Series: IAmA restoration ecologist focused on restoring oysters to the NY Harbor in New York City. AMA!
3994
How does sunscreen stop you from getting burnt?
14
Why does sunburnt skin feel hot to the touch?
2874
How are drugs like antidepressants (who’s effects aren’t immediately apparent) developed?
9
Why do images on a monitor become negtive when viewed from a certain angle?
4
What factors affect the orbit of our sun around the galaxy?
3
How were the subduction zones discovered and observed?
3
How far in advance can we predict a major tectonic event?
6
Why doesn't concentration affect the rate constant?
4
How does a catalyst affect activation energy?
11
Why does the space shuttle's transonic transition end so abruptly (see linked video)?
5505
In the last 5-10 years, there’s been tremendous efforts made by many of the first world countries to curb carbon emissions. Have we made a dent?
13
Why does the United States generally have a colder climate than most of Western Europe despite being at the same lattitude, and some parts even being further south?
2
In beta decay is the neutrino always in the subatomic particle or is it created from nuclear energy when it is released?
1
How do we tell a river from a tributary of a river?
7
Do bees have spatial memory when foraging for food?
30
How do spacewalking astronauts get rid of body heat and CO2 they generate?
2
How does the photon detector really work in Young’s experiment?
2
How often do collisions in LEO happen?
1
Are miniature Krypton and Xenon "glow bulbs" possible?
7
Why do people start to shrink once they get past a certain age?
3127
Why doesn't microwave energy escape through the holes in the screen of a microwave oven?
15
How does the mind make up a physical feeling you've never experienced before while dreaming? For example, a virgin having a wet dream or having a foot amputated?
13
How do we know the composition of Earth's core?
0
How long do microwaves stay active once it beeps?
4
Suppose in an X speaking country, a child is raised by 2 parents; one speaks Y language around them, the other speaks Z language. What's the science behind this kid learning to differentiate all three languages and eventually being able to speak all 3, as opposed to if they were only exposed to 1?
24
Why does alcohol kill bacteria?
20
Why is the output power greater than the input power for a microwave?
3
Is chemical rocket exhaust usually a plasma?
5
Why do 3 polarising filters, at certain angles, allow some light through when two are at right-angles?
3
Why don't lakes with streams flowing into other lakes eventually completely drain into the other lake?
8
Why do car wheels look like they're rolling backward when moving fast?
5
How do plants react to opiates? If I were to, say, use fentanyl as fertilizer, would the plant die? And what about other popular types of drugs, such as coke?
8
When can you consoder a organism dead?
14
Does hydraulic fracturing contribute to increased seismic activity(earthquakes) and how likely is it for the mix of chemicals+water ,that are used to displace the shale, to contaminate wells and body’s of water?
4
Does everything rotate in space? If so, why?
10
Do animals have a really good sense of time or is it confirmation bias by humans?
3
Are there animals whose evolutionary lineage we are unsure of?
2
Why does peak expiratory flow reach its peak around 30-35?
11
What is the difference between an imaginary friend and a hallucination? What about Tulpas?
2
Where do scientists come up with temporal timelines for dinosaurs?
16 lythronax-argestes Yes, there are theoretical upper limits on the maximum size which can be attained by any given animal group. (The below is from sauropod biomechanics researcher Heinrich Mallison at [[1]](http://www.askabiologist.org.uk/answers/viewtopic.php?pid=15164#p15164).) At a superficial level, a big animal requires a lot of sustenance for both metabolism and locomotion. In particular, metabolism gets a lot less efficient for large animals as the surface area becomes very small relative to the volume (per the square-cube law). Overheating or starvation would be problems for large animals, which would be exacerbated if the climate of the time is unfavourable (i.e. heat waves, or droughts leading to a lack of food). Then, once you get down to an animal's skeletal structure (talking about vertebrates here), the square-cube law strikes again. Of course, as an animal's volume grows, its weight grows accordingly. However, the tensile strength of muscles and bones do not scale cubically; they scale quadratically. So it becomes harder for an animal's skeletal structure to support it as it grows. Sauropod dinosaurs were really pushing it in terms of the size limit, and they "cheated" in many ways, so to speak. They have columnar limbs, which improves support, and they have bones lightened by air sacs, which reduces weight. Air sacs also alleviated the thermoregulatory problem. And of course their long necks are specializations for efficiently acquiring food.
2 the-real-apelord The base reasons from a structural POV are that: -Mass and therefore weight scales cubically so if something is made 2x bigger in size it becomes 8x heavier -But the cross-sectional area of the load bearing elements (legs for example) only increases with the square of scale so 2x bigger gives you just 4x the area to support 8x the weight so, in this example, the stress (force/area) has doubled. -All materials and structures have a limit to the amount of force/area they can sustain and at some point with increasing size will eventually fail (pancake in pure compression). In short weight grows faster than the area over which the weight has to be spread as a creature increases in size. Another limit is of course the presence of gravity, since weight only exists in a gravitational field. However it's worth noting that even in zero gravity there's limits on the size of a living thing, if that thing hopes to move, since as before mass increases cubically meaning forces required (for same acceleration) increase cubically but again those forces are spread over areas that is only growing with square of scale. There's a cool book called: "Why things don't fall down" that covers this question and lots else.
1 annomandaris Its mostly the square-cubed law, as anything gets bigger, its volume gets bigger a lot faster than its cross-sectional area. so if you take an animals leg, and double length/height/thickness of it, its cross-section will square, but its volume will be cubed. So basically theres a point where that animal thats getting bigger, the bone cant take the weight, and would just split apart. Also the bigger an animal gets, the bigger the problem of overheating gets, getting oxygen to areas of the body, and just how much it has to eat. Brontosaurus's were about as big as an animal can be, and if you notice they have short stubby legs that are really thick and short. and most of their size was a skinny neck and tail.
-2 lbruss95 some animals were able to attain massive size due to oxygen availability at the time, with that many resources it was a viable evolutionary strategy to be huge as to avoid predation. If an environment were created with "unlimited" resources, large predators would increase in size to out compete each other. mountain sized animals didn't exist because that would have no evolutionary benefit within an individual's lifetime.
16 0 lythronax-argestes Yes, there are theoretical upper limits on the maximum size which can be attained by any given animal group. (The below is from sauropod biomechanics researcher Heinrich Mallison at [[1]](http://www.askabiologist.org.uk/answers/viewtopic.php?pid=15164#p15164).) At a superficial level, a big animal requires a lot of sustenance for both metabolism and locomotion. In particular, metabolism gets a lot less efficient for large animals as the surface area becomes very small relative to the volume (per the square-cube law). Overheating or starvation would be problems for large animals, which would be exacerbated if the climate of the time is unfavourable (i.e. heat waves, or droughts leading to a lack of food). Then, once you get down to an animal's skeletal structure (talking about vertebrates here), the square-cube law strikes again. Of course, as an animal's volume grows, its weight grows accordingly. However, the tensile strength of muscles and bones do not scale cubically; they scale quadratically. So it becomes harder for an animal's skeletal structure to support it as it grows. Sauropod dinosaurs were really pushing it in terms of the size limit, and they "cheated" in many ways, so to speak. They have columnar limbs, which improves support, and they have bones lightened by air sacs, which reduces weight. Air sacs also alleviated the thermoregulatory problem. And of course their long necks are specializations for efficiently acquiring food.
2 0 the-real-apelord The base reasons from a structural POV are that: -Mass and therefore weight scales cubically so if something is made 2x bigger in size it becomes 8x heavier -But the cross-sectional area of the load bearing elements (legs for example) only increases with the square of scale so 2x bigger gives you just 4x the area to support 8x the weight so, in this example, the stress (force/area) has doubled. -All materials and structures have a limit to the amount of force/area they can sustain and at some point with increasing size will eventually fail (pancake in pure compression). In short weight grows faster than the area over which the weight has to be spread as a creature increases in size. Another limit is of course the presence of gravity, since weight only exists in a gravitational field. However it's worth noting that even in zero gravity there's limits on the size of a living thing, if that thing hopes to move, since as before mass increases cubically meaning forces required (for same acceleration) increase cubically but again those forces are spread over areas that is only growing with square of scale. There's a cool book called: "Why things don't fall down" that covers this question and lots else.
1 0 annomandaris Its mostly the square-cubed law, as anything gets bigger, its volume gets bigger a lot faster than its cross-sectional area. so if you take an animals leg, and double length/height/thickness of it, its cross-section will square, but its volume will be cubed. So basically theres a point where that animal thats getting bigger, the bone cant take the weight, and would just split apart. Also the bigger an animal gets, the bigger the problem of overheating gets, getting oxygen to areas of the body, and just how much it has to eat. Brontosaurus's were about as big as an animal can be, and if you notice they have short stubby legs that are really thick and short. and most of their size was a skinny neck and tail.
0 0 lbruss95 some animals were able to attain massive size due to oxygen availability at the time, with that many resources it was a viable evolutionary strategy to be huge as to avoid predation. If an environment were created with "unlimited" resources, large predators would increase in size to out compete each other. mountain sized animals didn't exist because that would have no evolutionary benefit within an individual's lifetime.