Why does an electron inside an atom not fall into the nucleus?

Question

Why does an electron inside an atom not fall into the nucleus?

Answer 1

Let's imagine that you have a guitar and when you pluck one of the strings, you hear a particular note. If you do it again, guess what? You hear the same note. The point I'm making is that the guitar string cannot vibrate in any old way. It can only vibrate in a set pattern determined by its physical properties. If you shorten the string length it'll produce a higher note. If you lengthen it, it'll produce a lower note. If you apply more tension to it, it'll produce a higher note. And so on ...



An electron behaves in a similar way to a string. It is not a particle like a little sphere but a fuzzy object described by probabilities. And those probabilities are described by a wave equation. So what happens in an atom is that you have an electron described by a probability wave. Because of the dimensions of the atom, the forces acting on the electron from other electrons and from the nucleus itself, the electron probability wave can't vibrate in any old way. Like the guitar string it can only vibrate in certain ways.



So let's imagine an electron as a wave. To be in the nucleus the wave would have to be smaller than the nucleus. It would have to be unchanging so the electron probability of being inside the nucleus would be 100%. And what you find is that this would mean that the electron wave has to vibrate in a way that isn't allowed by the physical system, in a similar way to you tightening a guitar string and finding the note gets much lower ... that's not allowed!



And if you do the maths very carefully and look at the ways in which electron waves ARE allowed to vibrate then you find you get interesting 3D shapes. Some are shaped like spheres (the probability of finding the electron on that sphere is high), some are shaped like dumbbells, some are close to the nucleus, some are further away ... these are the electron orbitals of an atom that allow chemical bonds (s-orbitals, p-orbitals, etc).



So, the reason electrons don't fall into the nucleus is because they act like waves and can only 'vibrate' in particular ways, none of which allow them to be inside the nucleus!

Answer 2

This is one of the best questions I've ever seen asked here. Actually, this was one of the questions that led to the discovery of quantum physics!



The "easy" (but incomplete) answer is because it is orbiting the nucleus, like a planet orbiting the sun. You can read about planetary orbits to understand more about how that works. Or, sometimes it might be bouncing back and forth through the nucleus. An electron can pass through a nucleus without affecting it.



But these ideas don't completely answer the question. That's because whenever a charged object like an electron accelerates, it emits light. Both orbiting and bouncing are acceleration. So if that electron is orbiting or bouncing, it seems like it should be emitting light. That light would use up some of the electron's energy and momentum. So the electron should slow down and crash into the nucleus after all! Why doesn't it?



The surprising answer turns out to be that light is made up of little pieces called "photons". Each photon must contain a certain amount of energy and momentum. So if the orbiting or bouncing electron doesn't have enough energy or momentum to create a whole photon, then it's impossible for it to emit any light!



So that's the reason. The electron has to keep moving because it can't release its energy as a photon, because it has less than one photon worth of energy. The photon is what is called a "quantum" of light. A "quantum" is just the tiniest possible piece of something. And so we say that light is "quantized", and therefore the electron's motion is also quantized. That's the beginning of quantum physics!

Answer 3

An electron circling a nucleus is actually a WAVE circling a nucleus. ---and the wave must consist of WHOLE cycles----1, 2 or 3, etc. So that means that electron waves can only circle a nucleus at certain SET distances around the nucleus---to accommodate all the cycles such waves may have. A one cycle per circle is the lowest possible "orbit" and energy state of am electron---The more cycles it has, the farther away it must orbit to accommodate whole cycles. THS is the reason atoms have electron "shells" specific levels where electrons orbit.----Electrons can't have NO cycles in the nucleus, they would not be waves, so are not found there.



Of course the entire truth is a bit more complex, as electrons can sometimes be considered particles, but not in this context.--- but the above is the general principle.

Answer 4

While I respect xezlec's answer, there's much more to this admirable question than meets the eye.



First and foremost is this - matter is a concept - an idea, structured through physics, latticed by chemistry, and anthropomorphized by biology.



Now it's important to understand that while xezlec's answer is technically correct, that's like comparing Steve Vai as a guitarist to Eddie Van Halen - it works in one instance and one instance alone in a materially based world.



Everything. All matter is a concept, an idea. While the Big Bang Theory suggests it all blow up from a single point in space and time and the physical forces are the only thing holding the entire kit and kaboodle together, there's more to it than that.



Accordingly. An atom is a concept. An idea you hold in your mind as do a great number of people. It's the belief in this structure that holds it together. It's the belief in the integrity of the system as a whole which has it not falling apart like a house of cards.



The electron is a figment of your imagination.



And while I have yet to see an actual atom without the use of tools which claim to be looking at the atomic world. I myself believe in a physical universe and world that doesn't need atoms and scientists to be accurate and this corresponding belief to be accurate for it to function.



So to answer your question in honesty: I suspect belief is the forces is what prevents the fall. And belief sustains those forces. So while technically, xezlec was accurate with his assertion of forces, the next question would be where do those forces come from.



Which is YOU.

Answer 5

Why our heart does not fall into the stomach? Why Earth does not fall into the Sun? Why the eyes does not fall into the brain? Answer: because the space between them is not empty. The space can be fulfilled with meat, fat,blood, or with non-visible gravitational force, or electromagnetic force... be sure the space inside atoms are fulfilled by some force.



But, my Matrix/DNA Theory would ask you: " Why a human at adult shape can not fall into its own teenager shape? What separates the adult from the teenager is only time, and time is not a substance filling space. The answer is that atom is a system. And systems are built by the process of life's cycles. If you could fix the seven shapes of a human body during its lifetime, you would get a new system, the familiar system. Systems are formed by those seven different shapes fixed at the same momentum, keeping the dynamic link of time among them. See my avatar, showing how the building block of galaxies are formed by same life cycle of human beings. of course: galaxies are our ancestrals, like reptiles and bacteria...

So, the atom has a nucleus and seven orbitals. Each orbital is a shape of the system during its lifetime. Electrons are merely the energy that express an orbital. That's why we didn't know if electron is particle or wave. It is the energy of the orbital.

So, atom is our ancestral system, but, so primitive that it does not express all organs, all parts at same time. When you see an atom with two electrons/two orbitals is like you see walking in the street only a stomach and a heart of a human body. The others parts of a human body system are not expressed. Atoms are our ancestrals, they are alive, in their primitive way. But... remember that Matrix/DNA Theory is a new world view being tested against facts (http://theuniversalmatrix.com)



Your human actual shape is your self momentum/vibrational state. It is different of yours past baby systemic state, teenager state, etc. That's why in the first answer above the commenter told that the reason is that the electron vibrates in different scale.

Answer 6

In the quantum mechanics description of the atom, the electron isn't at a single location. It occupies a cloud in and around the nucleus. That is the lowest energy state. It does in fact have some probability of being inside the nucleus.

Answer 7

The electron in the shell is orbiting and it stays up for a similar reason as to why the moon does not crash to earth in 7 days or the earth does not crash into the sun in three months.



You need to study "circular motion"



If you are dealing with an electron inside the nucleus ( which can be emitted as a beta particle) then it is already in the nucleus so the question would not make sense.

Answer 8

According to planetary model of atom, an electron is orbiting the nucleus like planets move around the Sun. This moving prevent falling.

Answer 9

In actual fact, some of the electrons do spend some of their time right inside the nucleus, but they never fall in, because they aren't really particles in the sense that we think of it. It's best not to even think of them as particles, but as probability clouds, that can pass through one another.



For example, take a look at these pictures of various electron orbitals. The electrons at the lowest energy state, i.e. the ground state, have their probability cloud overlapping the probability cloud of the nucleus itself.



https://d2gne97vdumgn3.cloudfront.net/api/file/yE4Ih2ooS69wA31JiLxa



This has nothing to do with the speed of the electron orbiting so fast that it doesn't fall in, it's not like a planet orbiting a star. In the quantum world, things just exist smeared over large volumes which touch and overlap one another.

Answer 10

Theoretically it can pass through the nucleus, just can't remain there. Then again the atom may have electrons but there is no reason for them to be anywhere near the atom. There is no definitive reason, guess because that would make transmutation of elements way to easy.

Answer 11

Electrons DO "pass through" an atoms nucleus and CAN bond with the protons within, however in almost all cases they do not. Electrons have particle/wave duality which by Schrodinger's equation their "exact" position or momentum may be calculated, sacrificing one for a more precise result of the other due to Heisenberg's Uncertainty Principle. In other words a perfect position point measurement results in a "wavelike" momentum measurement. Electrons do have a probability of passing through the atom's nucleus. However based on this position/momentum flipflop they cannot simultaneously exist as a point particle inside of the nucleus without momentum exhibiting a wavelike nature meaning its energy cannot then be pinpointed accurately. By this reasoning it is not possible for the electron to be in the nucleus without being energetically unfavorable for it to bond with the protons because of the high momentum as a result of its not losing energy as a standing wave, and thus it continues on its cloudlike "orbitals". People stating centripetal force are following the planetary or Bohr model which are not accurate or followed today, having been replaced with more accurate descriptions following quantum mechanics. It's best not to think of the electrons as moving in orbitals like particles floating around the nucleus, but more like the electron being everywhere around that "orbital path" at the same time as a standing wave (like when you shake a rope perfectly so that certain points of it seem to stand still while the other points oscillate up and down). The only element for which Schrodinger's equation can be solved exactly is Hydrogen, and approximation is necessary for the rest generally based off of the Hydrogen model. However, WHEN it is energetically favorable the electron may fall into the nucleus. This is known as "electron capture" and may be witnessed in the decays of certain isotopes of elements, such as the decay of Rubidium-83 to Krypton-83. So basically it is not feasible in most general cases, but in certain cases may occur and causes decay (or breakdown into lesser elements) of the element at hand.



My question is: Why are xezlec's and Randy P's comments downrated when they are by far the most apt/accurate descriptions of the phenomenon? The "best answer" literally doesn't explain this at all, but only that electrons can be thought of as waves (excluding the particle in wave/particle duality).

Answer 12

In addition to keeping drawings stuck to the refrigerator, the electromagnetic force also keeps electrons in orbit. Electrons have a negative charge, and the nucleus has a positive charge. Opposites attract, and so the atom holds together.

Answer 13

The electron is similar to satellite that is orbiting earth. The following equation is used to determine the force of attraction between the electron and the nucleus of the atom.



F = k * q1 * q2 ÷ r^2



The following equation is used to determine the force of attraction between the earth and a satellite.



Fg = G * M * m ÷ r^2



In both of these equations the magnitude of the force of attraction is inversely proportional to the square of the radius of the orbit. For the satellite to move around the earth at a constant speed, the centripetal force must be equal to the Universal gravitational force.



Fc = m * v^2 ÷ r

m * v^2 ÷ r = G * M * m ÷ r^2

v = √(G * M ÷ r)



This equation can be used to determine the speed of satellite at a specific distance from the center of the earth. For the electron to orbit the nucleus at a constant speed, the centripetal force must be equal to the electric force of attraction.



https://www.khanacademy.org/science/physics/centripetal-force-and-gravitation/centripetal-acceleration-tutoria/a/what-is-centripetal-acceleration



If you go to the website above, you will see a drawing of an object that moving around a circle a constant speed. The centripetal force does not magnitude of the object’s velocity. The centripetal force changes the direction of its velocity. In your question, the electric force is constantly changing the direction of the electron’s velocity. The fact that atoms do not collapse proves that the electrons must be moving fast enough to prevent this from happening. I hope this is helpful for you.

Answer 14

At quantum level the size is equal to cube of de-broglie wave length. This volume turns out to be very much larger than the size of the nucleus. Therefore, it covers entire nucleus like a seed (nucleus)in a apple ( volume of the electron).

Answer 15

The electron in the shell is orbiting and it stays up for a similar reason as to why the moon does not crash to earth in 7 days or the earth does not crash into the sun in three months.



You need to study "circular motion"



If you are dealing with an electron inside the nucleus ( which can be emitted as a beta particle) then it is already in the nucleus so the question would not make sense.

Answer 16

Subatomic particles do not touch, yet the fields of the positive charged nucleus and the negative charged electron attract and sustain each other. That's just how it is. Our physical reality is a perceptual interpretation of compressed particle/wave form, detected by the senses as impulse signals, which travel the nervous system to the brain. The tangible world is "solid", only because we believe it is.

Answer 17

This is NOTHING to do with motion or anything classical, this is pure quantum mechanics.

For the Electron to approach the Proton it must lose energy. It can only lose energy by emitting a photon. Now, depending on the energy state of the Electron AND the total number of Protons (and a few other things) the Electron is only able to emit photons of specific energy (or colour if you prefer). If the energy to be emitted does not fit a permitted photon then the electron cannot change its energy state and fall to the Proton.

Answer 18

It would violate the Heisenberg relation for space and momentum uncertainty. If the electron would be locatable very near to the nucleus, then the uncertainty in position would be very small. But that means that the uncertainty in momentum must be very big, leading to an increase in kinetic energy. In this way the uncertainty principle explains the stability (incompressibility) of matter. The reason we don't squash into the floor is quantum mechanics!

Answer 19

It has sufficient energy to be part of the electron cloud and whether it occupies the s,p,d or f sub orbitals depends on the electronic configuration.

Answer 20

Because it has to fly around in motion. The question is why doesn't it fly away from the atom. What holds it?

Answer 21

ot fall into the nucleus? Roman Catholic sign of the cross is upside down, done with five fingers instead of three, is done from left to right instead of right to left, etc. (basically inviting demons). Antichrist's Third Temple will have 8 chambers: a chamber per main religion; antichrist will be crowned in this temple; during crowning, he won't read the "belief prayer" correctly (rejecting Christ and acknowledging himself); when he will take his gloves off to make sign of the cross incorrectly (just for show), many people will see his big nails and will reject him; Patriarch (who will be crowning him) will say that this is the antichrist; antichrist will kill him. Also, antichrist will kill those priests who disagree with him at the 8th "wolf" Council; others will worship him when a bird dies at his feet. Roman Catholics, Satanists, and Buddhists use the same mudras; if you see these mudras on an icon, then it's not Orthodox icon; Orthodox icon has IC XC symbol (Jesus Christ). Roman Catholics pay drunks and prostitutes to pose for icons; passions of drunks and prostitutes transfer to those who pray to these images. Normal Orthodox icons are inspired by the Holy Spirit. Gaad in Ruski = Satan; hence, Americans = blasphemers because they always say: "Oh, my god!". Santa (word for Saint in Satanic languages) = Satan; hence, Spanish + Italian + Portuguese = blasphemers. Anathema to Satanic languages; triple anathema. Learn Church Slavonic; no curses in it; curses = prayer to Satan. All religions except Orthodoxy worship Satan. On bread for communion: IC XC NIKA (Jesus Christ Conquers) plus cross = Orthodox; hexagram plus Dusha Maya = antichrist. Jews and Muslims pray head down (either standing, bowing, or kneeling); this is Satanic prayer. Orthodox look into the eyes of icon; energy goes their way; they get healed; head and shoulders come together to reject Satan slowly and then fast to normal showing allegiance to Christ and not the devil. Hands cannot be on groin or behind back; either put them crossing each other on chest (right over left) or just by your sides. Legs together so that a demon doesn't run underneath your legs. Clergy who will not "put Buddhist icons and serve antichrist's blood" will be killed; only 7 churches will be left as Pelageya of Ryazan predicted. In 2006 and at other meetings, fake patriarchs and bishops signed a bunch of documents betraying Orthodoxy by saying that all religions worship the same Supreme Being; triple anathema; don't let heretics tell you what to do. America will be last country to switch to Euro. Three big earthquakes will shake the three superpowers; 1st big earthquake in Russia; 2nd (bigger one) in China; 3rd (biggest of the three) will be in America. NATO will nuke Ukraine to blame Russia for it; then NATO will nuke Russia from Scandinavia. China will attack Russia; but will not get past Ural Mountains; bio-genetic weapon will be used against Chinese soldiers (they will run back to China and hide in closets in fear) and weather weapon will freeze Siberia to - 200 Celcius; stadium-size chunks of unmeltable ice will fall from the lower sky (because when rockets go into higher sky they bring this ice down to lower sky). Russia will destroy Turkey and America. China will have a hole across the whole country to the abyss (because of another super weapon used to stop Chinese aggression); radiation from this hole will be massive; Chinese will try to keep quiet about it; a lot of people will fall into this hole.

Scientists don't see dinosaurs because of radiation. Only Eurasia and Alaska (both without coasts) will remain after demons blow up Antarctica (which surrounds the flat earth) and Greenland melts. Move to Ural Mountains or inland Alaska. Sionists wanted war between Russia and Germany from June 11th to October 11th on their holidays because (666 times 3)+(6 times 3) = 2016 (in their twisted logic).

Tube people = demons. Clones = demons. Human costumes that demons wear = demons. Dinosaurs and 666ed people have triple stranded DNA; normal person can't swallow 666ed food (designed for 666ed people). Demons live inside clones. Bacteriologist Alexandre Yersin (who discovered Bubonic plague) is depicted on the Shroud of Turin. There is another shroud (Shroud of Milan) on which blasphemer Yosef (who was crucified on a pole in 1066 AD) is depicted. Menachem Mendel Schneerson, Lenin (el=deity in Hebrew, nine = no in German; so, when chanted repeatedly is blasphemy against the Creator), and Yosef were possessed by Azazel; now, Rico Cortes is possessed by Azazel.

WW3 happens; 7% of people will be left; after people are tired of war, they will elect the antichrist as one world leader; don't vote. ISIS stands for Israeli Secret Intelligence Service. Next false flag: Statue of Liberty in order to attack Iran; one big shake, one giant step forward, one giant collapse. Move away from coasts as nukes will go off in the ocean (at where tectonic plates meet; result: megatsunamis 1km high).

Wear natural clothing so that if a bomb goes off it won't stick to the body as fast as synthetic clothes. All metal will be burned for fuel; so, save knives, crowbars, shovels, wood-burning stoves, etc. Also, save cloth/fabric/textile to cover the wounds and diseases.

Eat natural food because nanochips, cells of aborted fetuses, bug DNA, and other poisons are in food that is commonly sold; reject vaccines, medical care, medicine, etc. because nanochips are administered thru IVs, implants, fillings, etc. If 1000-1500 nanochips are in your right hand, then you can't make proper Orthodox sign of the cross with the right hand; last mercy for you then will be to cut the hand off.

Seraphim of Sarov and Sergiy of Radonezh will be resurrected after WW3 for a short time; Seraphim of Sarov will show the new Ruski Tsar who will fight the antichrist for about 2 years and 8 months. Those who go see Seraphim of Sarov will be healed of their infirmities/illnesses/sicknesses/ diseases; if you want to see him then, hurry because he won't stay longer than a few weeks.

Earth is flat; stands on 3 pillars (the Most Holy Trinity); pillars stand on water at zero Kelvin. Zodiac is planetary prison of demons; don't believe in horoscopes or you'll exhibit the traits of the trapped demons. Most thoughts and dreams are from demons; demons never do good. Sleep fully clothed; pray the Jesus prayer. Pray to your guardian angel to have normal sleep.

Humans were created about 7525 years ago. Ruski Orthodox Christian Vyacheslav Krasheninnikov was the last prophet before Enoch and Elijah return to preach against the antichrist.

Birds participate in time creation. It's a sin to kill birds. Dinosaurs live under our level. They will get out through sinkholes and lakes. To kill them, go for their nerves. Save the birds; but kill the dinosaurs. First dinosaur will come out of Volga River in Russia.

Demons grow human skin (from a sample taken during abduction) and put it on so as to look like us. Demons will invite people to be healed inside their UFOs; those who go will be like zombies after. Gov't provides demons with diamonds and allows demons to abduct people. If you're being abducted, slowly pray the Jesus prayer.



Don't panic. Demons use diamonds and souls to power their UFO craft. The bigger the diamond, the more it lasts. Demons have 4 UFO bases: 1)Moon 2)Inside fake mountain Kailash in Tibet 3)In lake Baikal in Russia 4)In Atlantis which is underneath the Mariana Trench in Pacific Ocean. There are no aliens. Nobody lives on other planets.

Airplanes that go down are hit by demons because they need the airspace to fight Jesus. Antichrist is pale with red eyes. He's possessed by Satan since he's 12 years old. He flies very fast; deceived people will say that "Christ is here; Christ is there". Sometimes, he wears blue robe over left shoulder while red robe is underneath. He wears gloves to hide long nails. He's surrounded by demons who appear as angels of light. Antichrist will trick people to believe that he can do mountain moving and resurrection (using holograms); fire from the sky is easy (considering the gases from pollution in the atmosphere).

Don't go into a UFO to be healed by demons. Green 666 is given by isotope rays on wrist or forehead when people stretch hands to receive small plastic grey card with no name on it (World Passport). Police will microchip and isotope ray people on the highways. Microchipped people will be influenced by computers to take grey plastic card; but when they do, 666 is given. Food stores will isotope ray people too. Antichrist will also release prisoners to mark people. Reject 666 at all cost because it leads to permanent hell.

If you're about to be marked, pray the Jesus prayer. Hide with Orthodox Christians to escape 666; leave all electronics behind so that antichrist's minions can't track you. Burn documents because they're from Satan. Give to charity in the name of Archangel Michael; he rescues people from temporary hell twice a year (or brings them up a level, that is, to a level with less punishment; eventually, people are freed). Feed the pigeons; when pigeons bow down, people are saved from temporary hell. Forgive me.



https://youtube.com/watch?v=8dub8PF2d8E

http://fatheralexander.org/graphics/sects_e.pdf

http://cs629216.vk.me/v629216013/6f4c/Qji_GVZorQY.jpg

http://ic.pics.livejournal.com/m_e_l_n_i_k_o_v/30839524/10997/10997_original.jpg

https://vk.com/wall-25720730?q=рязанская&w=wall-25720730_57029%2Fall



https://youtube.com/channel/UCql8z99xa5QH8nSdkfnzIkw/videos

http://vk.com/otrok_slava?w=wall-31832035_103469%2Fall

http://orthodoxinfo.com/praxis/guidech3.pdf

http://fatheralexander.org/booklets/english/life_after_death.htm

http://pravoslavie.ru/english/55141.htm

Answer 22

Neg vs pos

Answer 23

Pl. consider it only from some or the other philosophic angle. Then only you will come to know the real crux of the matter or essence.



I think one philosopher is earmarked to hold it tight.

Answer 24

I believe the correct answer is that we really do not know, but we do have some theories about why it does not. Some of these have been discussed previously better than I could.

Answer 25

Long response but I believe I address the question. Accelerating charges radiate away energy. If the system is losing energy, this implies that the orbit radius will become smaller and smaller.



Niels Bohr: Postulates that electrons could move in certain orbits without radiating. He called these orbits stationary states. He also postulates that an atom radiates when an electron makes a transition from one stationary state to another stationary state of lower energy. He uses these postulates to determine that the energy of stationary orbits are quantized. Bohr's model has been replaced by 'modern' quantum mechanics. However, his postulate that atoms only radiate when an electron transitions from one energy state to another lower energy state still remains. What changes essentially is the way you think of the word 'orbit' (and this changes a lot).



Louis de Broglie: Wave-particle duality. He pointed out that the stationary states that Bohr talked about could be thought of as standing waves. That is, Bohr's postulate that an electron can exist only in these special orbits that don't radiate away energy are standing waves. Classically, if you think of a particle orbiting around the nucleus, it's radiating away energy because it has centripetal acceleration. But if you think of a standing wave (forget the atom for a second, just think of a standing wave), energy isn't leaking out anywhere (assuming there are no energy loss mechanisms). Energy isn't traveling along like in a traveling wave. The energy is confined, oscillating between potential and kinetic energy. This gives a picture/"reason" at least to Bohr's postulate that there exists orbits where no energy is radiated away (they are standing waves).



Quantum Mechanics: Don't think about orbits in the classical sense. When you say 'orbit', what comes to mind (to me) is a path that it restricted to a plane (the plane can be in 3-space). Instead, the stationary states Bohr talked about are "clouds". These 'clouds' around the atom are not made of water vapor, but probability densities. But to answer your question: why doesn't an electron spiral into the nucleus? It spirals in because accelerated charges radiate away energy. So the question becomes: what happens to the radiation in quantum mechanics? Do these probability clouds still radiate away energy or not? First off it doesn't really make sense in the context of quantum mechanics since radiation (as thought of classically) requires acceleration and acceleration/velocity/position get muddled in quantum. Anyways, to truly answer your question, we must somehow explain why the radiation issue is no longer a problem in this quantum mechanical framework. It really just comes down to accepting Bohr when he said that there exists states where the electron won't radiate away energy - then using the standing wave picture to make this seem reasonable. Let's follow another train of thought. Since the electron is bound and not free, this results in an energy spectrum that is discrete as opposed to continuous. But even if you are in one of these stationary states of quantized energy, reverting back to our classical brains, why isn't the electron cloud radiating away energy? The discreteness of everything and the fuzziness of acceleration/velocity/position messes things up when we try to reconcile quantum with classical ideas of radiation (classical radiation assumes that energy is continuous and position/velocity is well defined). Because I can't really say what the electron 'is doing' while in this probability mess, it's hard to say why there is no classical radiation in a stationary state because I don't really understand what a stationary state is in my classical brain. Again, I believe it comes back to accepting Bohr's postulate that there are states (stationary states) where the electron won't radiate - then use Louis de Broglie's idea of standing waves to make it reasonable (As a side note: it is possible for the electron to radiate from one stationary state to another via processes called spontaneous or stimulated emission, but these aren't exactly 'classical radiation' processes. Remember, 'classical radiation' is what caused the problem in the first place). Anyways, for a more mathematical argument (instead of the 'accept Bohr and use de Broglie's standing wave' answer): when we have accelerated charges, charge density and current density change with time. In quantum mechanics, charge density ρ = q|ψ|², where q is charge and ψ is the wave function. Dimensionally, this makes sense since |ψ|² has units of inverse volume. In a stationary state,

ψ = e^(-iwt)f(r), where f(r) is some function of position r. Therefore since stationary states have this nice form where the time component is separate of f(r) and takes the form e^(-iwt), |ψ|² does not depend on time and ρ does not depend on time either. A similar conclusion can be made for the current density. If these things don't change with time (that is, the time derivatives of charge density and current density are zero), Maxwell's equations say that there will be no radiation (you might try looking at the Jefimenko equations and notice that if the time derivatives are zero, you get back the equations familiar from electrostatics/magnetostatics). What's tricky is that your question is posed from a classical physics point of view. Yet, when we go to a more accurate description of the atom given by quantum mechanics, we find ourselves trying to either answer/dismiss a classical question from a quantum point of view (while wanting to hold on to classical radiation/acceleration ideas). In the process, we have to be careful that we sort out classical and quantum ideas, which makes things difficult. Again, to truly answer your question, one has to deal with the problem of 'classical radiation' (which caused the problem in the first place) and quantum physics.

Answer 26

The Force. May it be with you.

Answer 27

the strong nuclear force

Answer 28

I think it has something to do with crop circles.

Answer 29

Because it's a rebel without a cause and does whatever it wants without a care in the world? I dunno. Why?

Answer 30

Because it moves too fast and is too far away.

Answer 31

pressure

Answer 32

.. idk