Score
Title
82
AskScience Panel of Scientists XVIII
263
AskScience AMA Series: "I am Rhett Allain, physicist and technical consultant on Mythbusters and MacGyver. Ask me about the physics of pretty much anything!
393
Can dogs observe and recognize aging in adult humans? Do they differentiate between young adult, middle-aged and elderly humans?
10968
When does a mushroom die? When it's picked? When it's packaged? Refrigerated? Sliced? Digested?
30
Is it possible to transform martian soil into fertile soil through bacteria and fungi?
9
Do cats purr voluntarily or unvoluntarily?
12
What is the most amount of electrons forcibly added to an atom?
9
Why does the taste of tap water vary between locations?
51
Why do things like saliva or melted cheese pull into strings when you try to separate them?
3
Are seatbelt/phone detection cameras a real thing? And if so, how do they work?
26
I think I understand the difference between aleph-null and aleph-one as countable and uncountable infinities, but what is aleph-two?
10
If the vaporization point of water can be changed by increasing pressure, is the freezing point also affected by pressure?
7
Do any of the stars we can observe with tbe naked eye at night have planets orbiting them?
5743
Does a Mayfly, which only lives a day, evolve fast than a human?
6
The failed recovery of the Falcon Heavy's central core was attributed to the booster running out of TEA-TEB. How does this happen if the amount of fluid needed to ignite the engine, and the number of ignitions required is known beforehand?
5
How do we know what an asteroid is made of?
5
How do developers of Nuclear Weapons either keep (or protect themselves from) radioactive materials like Plutonium-239 from potentially ‘leaking’ out particles? Are there any methods to contain these particles from escaping the material so they won’t hurt biological matter near the material?
7
How does a "loop sensor" in a street work?
4
How far can the human eye see?
2
Could a spacecraft under constant acceleration ever reach near-lightspeed?
5
I've heard that catfish have ring shaped pupils, however this rather surprising adaptation is only ever mentioned in passing. Can anyone provide more information on this?
5
Why are the late derivatives of position so weirdly named?
6
We often see water used as a neutron moderator in fission reactors due to its high Hydrogen content. Would gaseous Hydrogen be a more effective neutron moderator?
3
Could a neutrino interact with a water molecule in my eye and release a photon that I could "see"?
0
Is the threshold frequency for alloys based on the elements in the alloy, or is it a different factor in the photoelectric effect?
23
Are mitochondria significantly different in different species?
12
When a Li-ion battery is first manufactured, is it already charged? If so, how much and why that amount?
1
How do power outages cause transient voltage spikes?
1
How did scientists choose the elements and method by which to create an atomic bomb?
0
What does hacking usually entail? How much of it is like the glamorous stuff we see on tv and how much is just calling and asking for a password?
13
If the four dimensions of space and time are intertwined, why can we not rotate an object into "time" the same way we can rotate an object in 3D space?
132
As a snake grows in length, does it grow additional ribs and vertebrae, or do they have a set number?
4
If an event happens an average of every x years, and it is been >x years since it last happened, are we more likely to experience the event? If so, can this likelihood be predicted?
0
Will checkpoint inhibitors (PD1/PD-L1, CTLA4) cause the host immune system to generate neutralizing antibodies?
6
Why does halorhodopsin only activate when exposed to yellow light and channelrhodopsin with blue light?
5
At an atomic level, what makes a material better at compression or tension?
30
Why isn't Boron created through normal stellar nucleosynthesis (i.e. nuclear fusion in stars)?
1
Are there any approximations for masses of the various continents of Earth?
44
What is special about sunlight versus artificial light that plants need it?
4
Do male species having lower life expectancy than female also occur in other animal species than human?
14
How much complexity can nuclear pasta phases in neutron stars support? Could one potentially have strong-force-based life in a neutron star?
29
Do other animals have 'accents' like humans do?
7 Gargatua13013 We often get that kind of question, so have a look at the kind of data we have to work with. Mountain chains are highly dynamic environments which form in collision zones between 2 plates. Rocks from different initial depths are rearranged and [thrust/folded into different configurations](ftp://131.215.65.7/pub/avouac/Ge277-2010/Davis1983.pdf). At some point the process stops and you reach "peak mountain building" ... The mountain chain is at its tallest, and it all downhill from there (sorry). If you had a time machine you could actually go and measure the maximum altitude reached. But we can't and we don't. By the time we get to looking into those matters, time has passed and erosion taken large parts of the mountain chain away. So, what we actually do is look at the chemistry of the minerals which make up the metamorphic rocks formed under that mountain chain. As rocks of a given composition are brought to different pressure (P) and temperature (T) conditions, they undergo chemical reactions and re-equilibrate to different mineral assemblages. Some of these assemblages are particularly sensitive to temperature and pressure and act as [geothermobarometers](https://en.wikipedia.org/wiki/Geothermobarometry). They may rely on the ratios of trace elements incorporated in a specific mineral, or on isotopic ratios. Garnets and amphiboles are particularly well suited for these kind of studies, and allow the calculation of [P-T paths](https://www.researchgate.net/profile/Jane_Selverstone/publication/220021207_P-T_paths_from_garnet_zoning_A_new_technique_for_deciphering_tectonic_processes_in_crystalline_terranes/links/5489e1140cf214269f1abe5b/P-T-paths-from-garnet-zoning-A-new-technique-for-deciphering-tectonic-processes-in-crystalline-terranes.pdf), a historical trajectory through Temperature-Pressure space through which a given rock has passed. Add to that the possibility of using amphiboles or other minerals as geochonometers and you can calibrate those paths into the time (t) dimension, generating a P-T-t path. This allows you then to determine how much pressure that rock was under at a given time. But (and it's a huge but), translating that data into mountain altitude is not an easy thing. You have to make assumptions about heat flow, because geothermobarometers are temperature-dependant. There is a marging of error on the initial measurements, and they add up. So in the end you wind up with a range of possible heights, which seldom satisfies whomever asked the initial question. I hope this clears things up.
7 0 Gargatua13013 We often get that kind of question, so have a look at the kind of data we have to work with. Mountain chains are highly dynamic environments which form in collision zones between 2 plates. Rocks from different initial depths are rearranged and [thrust/folded into different configurations](ftp://131.215.65.7/pub/avouac/Ge277-2010/Davis1983.pdf). At some point the process stops and you reach "peak mountain building" ... The mountain chain is at its tallest, and it all downhill from there (sorry). If you had a time machine you could actually go and measure the maximum altitude reached. But we can't and we don't. By the time we get to looking into those matters, time has passed and erosion taken large parts of the mountain chain away. So, what we actually do is look at the chemistry of the minerals which make up the metamorphic rocks formed under that mountain chain. As rocks of a given composition are brought to different pressure (P) and temperature (T) conditions, they undergo chemical reactions and re-equilibrate to different mineral assemblages. Some of these assemblages are particularly sensitive to temperature and pressure and act as [geothermobarometers](https://en.wikipedia.org/wiki/Geothermobarometry). They may rely on the ratios of trace elements incorporated in a specific mineral, or on isotopic ratios. Garnets and amphiboles are particularly well suited for these kind of studies, and allow the calculation of [P-T paths](https://www.researchgate.net/profile/Jane_Selverstone/publication/220021207_P-T_paths_from_garnet_zoning_A_new_technique_for_deciphering_tectonic_processes_in_crystalline_terranes/links/5489e1140cf214269f1abe5b/P-T-paths-from-garnet-zoning-A-new-technique-for-deciphering-tectonic-processes-in-crystalline-terranes.pdf), a historical trajectory through Temperature-Pressure space through which a given rock has passed. Add to that the possibility of using amphiboles or other minerals as geochonometers and you can calibrate those paths into the time (t) dimension, generating a P-T-t path. This allows you then to determine how much pressure that rock was under at a given time. But (and it's a huge but), translating that data into mountain altitude is not an easy thing. You have to make assumptions about heat flow, because geothermobarometers are temperature-dependant. There is a marging of error on the initial measurements, and they add up. So in the end you wind up with a range of possible heights, which seldom satisfies whomever asked the initial question. I hope this clears things up.