Score
Title
547
AskScience Panel of Scientists XVII
414
AskScience AMA Series: I am a squid biologist, AMA!
2913
How do surgeons avoid air bubbles in the bloodstreams after an organ transplant?
6247
Why do joints ache so much when you get the cold/flu?
36
Are all massless particles their own antiparticles?
19
What do prion proteins naturally do in the brain/body?
780
What is the relationship between the rate of change of a function and differentiation?
502
If the energy of photons is continuous, and electron's energy levels around an atom are discreet, then how can you ever have a photon that has the exact energy to be absorbed by an electron?
32
How does coding physically work? How does a computer, made up of inanimate parts, understand what to do based on a made up language?
165
Why do "Y" chromosomes only have 3 chromatids?
9
Does the human body make any noticeable 'microadjustments' when exposed to a particular climate for a length of time?
7
Why do sperm cells have a large nucleus if they only carry half the genetic material?
8
What is thought to happen to quarks during the big rip?
8
How we know certain animals can detect specific scents from X distance away? How are we measuring and determining that?
11068
How do scientists studying antimatter MAKE the antimatter they study if all their tools are composed of regular matter?
3
Are there problems in computer science that no algorithm can solve for all inputs?
1
How do spacelike separated measurements of entangled particles work?
5
Does Urine Affect Plant Transpiration?
1
How do you actually use Density Functional Theory?
205
Can an unvaried diet cause the human body to learn to digest a certain (type of) food faster?
6
Is there a correlation between peoples hearing range and the type of music they like?
60
Why do large metal beams or trusses sometimes have tiny connections/joints?
1
How do you measure forces between individual atoms and molecules?
43
Does Supersymmetry include antimatter?
1
Why do some photos of the heavens show stars radiating light in a 'cross' shape instead of evenly in a circle?
3
I've recently been told that cloning different types of animals varies in difficulty. Is this true and if so what the key challenges in cloning different organisms?
1
Why does Nima Arkani-Hamed say we need an infinitely large apparatus to get rid of quantum uncertainty in measurements?
1
[Engineering] How do modern cars calculate fuel economy?
1
What exactly is the Doppler effect?
6
Why don’t everyday movements cause sub-concussive impacts?
3
Does our mother tongue affect our face features in any way?
1
What is physically different about the brain of someone with an exceptional memory?
29
Why is the waste produced in a thorium fuel cycle need storage for only 300 years instead of thousands of years for uranium fuel cycle, even though U233 from Th232 had mostly similar fission products as U235?
40
How did Scott and Amundsen KNOW when they reached the south pole (100 years ago)?
6
How does convection of heat work in space?
3
[Physics] Has there been significant research relating to anti-matter weaponry?
1
How does a paraconformity originate?
7
Can non ear neurons detect sounds?
990
If 2 black holes were close enough that their event horizons were overlapping, could things in that overlapped region escape those black holes?
4
Is it possible for gravity waves to have a particle nature? If so, what would this particle be like? If not, what sets gravitational waves apart from light and matter, which have particle wave duality?
6
Why is this year's influenza outbreak so much deadlier than previous years?
0
What are fingerprints made of ?
129 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!
708 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.
38 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.
4 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?
129 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!
700 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.
37 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.
5 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?