Score
Title
260
AskScience Panel of Scientists XVIII
624
AskScience AMA Series: IAmA restoration ecologist focused on restoring oysters to the NY Harbor in New York City. AMA!
969
How does sunscreen stop you from getting burnt?
2844
How are drugs like antidepressants (who’s effects aren’t immediately apparent) developed?
5494
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?
8
Why does the space shuttle's transonic transition end so abruptly (see linked video)?
30
How do spacewalking astronauts get rid of body heat and CO2 they generate?
3
How does a catalyst affect activation energy?
3122
Why doesn't microwave energy escape through the holes in the screen of a microwave oven?
5
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?
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?
2
How often do collisions in LEO happen?
4
Why do people start to shrink once they get past a certain age?
3
Do bees have spatial memory when foraging for food?
7
How do we know the composition of Earth's core?
3
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?
25
Why does alcohol kill bacteria?
22
Why is the output power greater than the input power for a microwave?
5
Why do 3 polarising filters, at certain angles, allow some light through when two are at right-angles?
0
What happens do humans blood brain barrier as we age?
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?
9
When can you consoder a organism dead?
2
Is chemical rocket exhaust usually a plasma?
12
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?
7
Why do car wheels look like they're rolling backward when moving fast?
4
Does everything rotate in space? If so, why?
2
Why don't lakes with streams flowing into other lakes eventually completely drain into the other lake?
9
Do animals have a really good sense of time or is it confirmation bias by humans?
10
What is the difference between an imaginary friend and a hallucination? What about Tulpas?
4
Where do scientists come up with temporal timelines for dinosaurs?
4987
This may be a stupid question, but what defines GMO. Is it simply changing a plant through cross pollinating (at its simplest level) such as Mendel, or does GMO mean laboratory tested and genetically altered through a laboratory?
14
What defines an “oil”?
136
Why is an Alpha particle denoted as a Helium atom?
0
When you pull at a slinky from the top, why does the bottom take a second to go with it?
3
a spider learns to build a net from other spiders or is it instinct ?
6
Why do molecules interact with others when they both have 8 valence electrons?
5
Is it more energy efficient to put cold water in a kettle, or hot water?
8
Do the planets in our solar system all orbit the sun on the same plane?
1
Which regions of the brain show diminished cell count with aging?
8
If Radiation is cumulative in our body, is Bluetooth (even with BLE) harmful to humans if we are constantly exposed to it with cellphones, smartwatch, etc. and also from other's electronic devices around us?
0
Can you feel the cold in space?
188
Are there any "weird" uses for heavy/transuranic elements?
133 Timbosconsin The redshift caused by gravity is called gravitational redshift, which is different than the better known cosmological redshift caused by the expansion of space itself. To answer your first question, yes, gravity wells do create their own redshift! For example, a photon leaving the surface of, say, a white dwarf star will lose energy as it climbs out of the gravitational potential well. As the light loses energy, it will decrease in frequency and be redshifted when observed. Moreover, gravitational redshift is only significant for massive and compact objects (black holes, neutron stars, white dwarfs) and not really for the sun since gas motions near the surface of the sun cause a Doppler shift in the frequency of departing light that is larger than the gravitational redshift. I’ll refrain from answering your second question since the posts above answered it well enough!
705 mfb- They estimate the depth of the gravity well. We sit in one ourselves so this can be taken into account as well. It doesn’t matter much. At distances where this is a large effect the random motion of galaxies is still important. At distances where you get nice measurements the redshift is so large the gravity wells don’t have a large impact any more.
37 ItOnly_Happened_Once Technically yes, but other effects end up being much larger - namely the expansion of space itself. Also, because black holes do not emit light, they end up not having much net effect on photons, as much of the blueshift cause while approaching is lost after it passes the black hole. The same is true for smaller gravity wells.
5 eenbiertje To jump on to this with a general relativity related question I've been pondering for a while. When we're tracking the movements of probes and spacecraft as they move through the solar system, do we have to account for the effects of general (and possibly special) relativity in maintaining accurate knowledge of their positions and to manage maintaining a signal with them? With the Juno probe for example. Does it's movement *away* from the Sun, or the Earth for that matter have to be factored into calculations which tell us exactly where it is, and what exact time its transmissions are sent? Similarly when it approaches a large body like Jupiter?
133 0 Timbosconsin The redshift caused by gravity is called gravitational redshift, which is different than the better known cosmological redshift caused by the expansion of space itself. To answer your first question, yes, gravity wells do create their own redshift! For example, a photon leaving the surface of, say, a white dwarf star will lose energy as it climbs out of the gravitational potential well. As the light loses energy, it will decrease in frequency and be redshifted when observed. Moreover, gravitational redshift is only significant for massive and compact objects (black holes, neutron stars, white dwarfs) and not really for the sun since gas motions near the surface of the sun cause a Doppler shift in the frequency of departing light that is larger than the gravitational redshift. I’ll refrain from answering your second question since the posts above answered it well enough!
704 0 mfb- They estimate the depth of the gravity well. We sit in one ourselves so this can be taken into account as well. It doesn’t matter much. At distances where this is a large effect the random motion of galaxies is still important. At distances where you get nice measurements the redshift is so large the gravity wells don’t have a large impact any more.
35 0 ItOnly_Happened_Once Technically yes, but other effects end up being much larger - namely the expansion of space itself. Also, because black holes do not emit light, they end up not having much net effect on photons, as much of the blueshift cause while approaching is lost after it passes the black hole. The same is true for smaller gravity wells.
3 0 eenbiertje To jump on to this with a general relativity related question I've been pondering for a while. When we're tracking the movements of probes and spacecraft as they move through the solar system, do we have to account for the effects of general (and possibly special) relativity in maintaining accurate knowledge of their positions and to manage maintaining a signal with them? With the Juno probe for example. Does it's movement *away* from the Sun, or the Earth for that matter have to be factored into calculations which tell us exactly where it is, and what exact time its transmissions are sent? Similarly when it approaches a large body like Jupiter?