Score
Title
386
AskScience Panel of Scientists XVII
6047
I’ve read that when caterpillars are in their cocoons, they dissolve completely into goo; no original parts survive in the butterfly. How is the butterfly made from the goo? Is there an embryo that grows and uses the goo like a yolk sac? Or does the goo somehow arrange itself into new body parts?
16382
With all this fuss about net neutrality, exactly how much are we relying on America for our regular global use of the internet?
38
How sustainable is our landfill trash disposal model in the US? What's the latest in trash tech?
41
If tooth decay is just caused by the bacteria feeding and producing acid, would a person that just used listerine have the same dental health as a person that brushed without flossing?
9
My doctor says that chemotherapy works by specifically targeting rapidly-dividing cells, which is how it works to fight cancer and also why it has the side effects that it does. But how does it “know” which cells are rapidly dividing? And how rapidly is “rapidly”?
15
How are isotopes used in nuclear physics Experiments isolated?
838
In 1996 NASA announced 'evidence of primitive life on early Mars'. In 2000, a second report supported the thesis. What happened next?
5
How mixable are different types of plastic? Like PET and HDPE?
82808
Help us fight for net neutrality!
3
What makes a laser shine in a straight line?
2
How are the needles for Atomic Force Microscopes made, and how can the tip be smaller than the atoms they are manipulating? What are their limitations?
5
How are the triple(or more) parachutes commonly seen on capsules returning from space kept apart?
2
Can animals understand human body language like laughing or smiling?
16
Could an electric vehicle stand a chance in a racing event?
21
If there is an ocean below the ice surface of Europa, is the ice shell buoyant? Geologically supported? Or is it kept in place by the distribution of gravity?
0
Lithium batteries are being developed to power cars in response to the decline in fossil fuels, but will lithium eventually run out as well?
4
How to calculate eigenvalues in the Kirchhoff's thin plate model?
3
Since the event at CERN that proved the existence of Higgs bosons/Higgs field, can we now see this event happen regularly now we know ‘where’ to look?
28
Do all individual atoms in a solid emanate their own blackbody radiation?
12
Is there anywhere other than Earth in the Solar system where you could see a total solar eclipse and/or total lunar eclipse equivalent?
5
How did we get solid matter from light? How did Photons and Electrons create solid matter in the early ages of the universe when everything was insanely hot?
7
Why does turning on an electric blender in the kitchen cause my HD antenna signal to go out in a different room?
5
Can the human body survive breathing pure oxygen at lower pressures?
18
When beryllium-16 decays and produces 2 neutrons simultaneously, what happens to that dineutron?
4
How do we know the earth’s core is super hot and why is it so?
1
How does the pressure of the vacuum of space affect the ISS?
11186
From my kid: Can you put a marshmallow on a stick out into space and roast it with the sun?
3
Given that cerebrospinal fluid flows around the structures of the brain, would messenger chemicals from synaptic activity in one area be passed to, and alter synaptic activity in other regions of the brain?
7
How do we know what the tonsil does?
2
In a compound with an alkene and an alkyne, which would ozone cleave in an oxidative cleavage reaction?
0
If every single human put a ac outside on a summer day and we all turned it on, would earth cool down or will the ac have no effect?
2
How does methanol form while making alcoholic drinks and how can it be prevented/removed?
6
Would there be a benefit to increasing the power of the planetary radar at Arecibo?
2
Why does the voltage in a circuit increase as the length of a wire increase?
10
How accurate is the usual picture of the atomic nucleus of a ball/mass of protons and neutrons? What's really happening in the centre of atoms?
9
[physics] When I turn off my oven but leave the door closed how does the temperature cool?
8
How would the government broadcast an emergency message in today's world where a majority of people watch tv through a streaming service?
3
What is the average density of interstellar clouds and at what density over a given volume is star formation triggered?
2
Does dark matter accumulate into dark objects (planets, stars, etc.)? Why?
8
How in the world could a particle have a 1/2 spin value?
196 RobusEtCeleritas In a beta-plus decay, it's not a single neutron which is decaying into a proton, it's an *entire nucleus* decaying into a new species. While a free proton can't decay into a neutron, beta particle, and neutrino due to energy conservation, an entire nucleus can decay to a species of lower mass by converting one of its protons into a neutron.
82 somedave An isolated proton is less massive than an isolated neutron yes, but a bound state of a neutron and proton is less massive than two isolated protons. This is due to the binding energy of the proton and neutron. Remember E = mc^2, so as the two isolated protons had more mass, they had more potential energy that the deuterium nucleus, this energy is released in a positron and neutrino that are emitted after fusion. Edit: Typo
17 [deleted] [removed]
6 centurion236 Classical physics gives us conservation of mass and energy, but these are approximations. Einstein proposed a system in which mass and energy are interchangeable, and mass-energy is conserved. You'll notice that every element is slightly lighter than the sum of its neutrons and protons. That "mass defect"is related to the forces and energy that holds the nucleus together. To enable positron decay, the decay must release enough energy to make up for the mass that is "spontaneously" created.
3 DrFeathers The whole system must have more energy than the state it wants to decay to. In the case of a free neutron you only have the neutron's mass to work with. Once you are in a nucleus, then you are considering the mass of all of the protons and neutrons as well as the binding energy. A proton can sort of "borrow" energy to allow a decay to happen, as long as the mass of the resulting nucleus will be lower.
193 0 RobusEtCeleritas In a beta-plus decay, it's not a single neutron which is decaying into a proton, it's an *entire nucleus* decaying into a new species. While a free proton can't decay into a neutron, beta particle, and neutrino due to energy conservation, an entire nucleus can decay to a species of lower mass by converting one of its protons into a neutron.
77 0 somedave An isolated proton is less massive than an isolated neutron yes, but a bound state of a neutron and proton is less massive than two isolated protons. This is due to the binding energy of the proton and neutron. Remember E = mc^2, so as the two isolated protons had more mass, they had more potential energy that the deuterium nucleus, this energy is released in a positron and neutrino that are emitted after fusion. Edit: Typo
18 0 [deleted] [removed]
5 0 centurion236 Classical physics gives us conservation of mass and energy, but these are approximations. Einstein proposed a system in which mass and energy are interchangeable, and mass-energy is conserved. You'll notice that every element is slightly lighter than the sum of its neutrons and protons. That "mass defect"is related to the forces and energy that holds the nucleus together. To enable positron decay, the decay must release enough energy to make up for the mass that is "spontaneously" created.
3 0 DrFeathers The whole system must have more energy than the state it wants to decay to. In the case of a free neutron you only have the neutron's mass to work with. Once you are in a nucleus, then you are considering the mass of all of the protons and neutrons as well as the binding energy. A proton can sort of "borrow" energy to allow a decay to happen, as long as the mass of the resulting nucleus will be lower.