In today’s“Ask a Physicist”we look at why electrons do n’t come down into their atomic cell nucleus , destroy all issue in the universe in the process .
I ’m belong to skip over the preamble , the dissection of the interrogation asked , requests for superhero questions , and needlessly wordyplugs , and do some one-time school quantum mechanics today . Our question come from Lisa Hewus who asks :
Why is it that the negatively bear down electrons do not “ hold fast ” to the positively charged protons of an particle when they are at their lowest energy state ?
Or , to put it another way , “ Why does n’t all weigh in the universe directly collapse ? ” I actualize that this is a bit more fundamental than some of the other things we ’ve blab out about , so if you know the answer , please do n’t smash it for the residue of the social class .
For those who do n’t already have their hands wildly thresh in the atmosphere , you ’d be forgive if you had a mistaken pictorial matter of atoms like the ones drawn in the logos of theNuclear Regulatory Commissionor the Springfield Nuclear Power Plant . In the toon version , there ’s a core group at the midsection with a bunch of negatron flying around in orbits , very much like the planets revolve the sunshine .
But this model has a serious problem . You need to constantly speed a particle to move it in an orbital cavity , but if you speed a charge particle , it give off radiation therapy . That ’s how a wireless transmitter works . The upshot is that if you really had a planet - corresponding electron flying around a nucleus , it would constantly give off Inner Light .
The vigour for that irradiation would have to hail from somewhere , and the electron is the only potential reservoir . Just like in a gravitational field , the electron would lose energy by decrease ever closer to the lens nucleus . This would happen ridiculously cursorily . For a hydrogen atom , it would take about 1 hundred one-billionth of a second for the negatron to slam into the karyon , destroy the atom entirely . The fact that atoms last much longer than that is a pretty undecomposed sign that something is wrong with the model .
So if you ’re think about an electron flying around in a particular place at a finicky time then you ’re think about it the wrong direction . When I talked about thedouble - slit experimenta few calendar week ago , I said that an electron does n’t go through one slit or another ; it really extend through both at the same time . In the precise same path , there is n’t a “ somewhere ” that the negatron “ really ” is when it ’s orbiting a nucleus . It literally is in many places at once – each with some probability . The distributions of probability are those orbital cloud that you may think back dimly from chemistry class . And it ’s not just our measurement incertitude that stops us from figuring out where the electron is . The universe really does n’t make love . It also does n’t know what the focal ratio or momentum is , which is why it really does n’t make sense to think about an electron “ orb ” the nucleus .
How Smart Do You ask To Be To Collapse A Wave Function ?
It ’s this uncertainty that really prevents atoms from collapsing . After all , if the negatron falls into the karyon then you ’d know exactly where to find it , and that ca n’t be .
Quantum mechanics even recount us how to measure our uncertainty via the famous “ Heisenberg Uncertainty Principle , ” which says that you ca n’t at the same time mensurate the placement and the momentum of a particle . In fact , you ca n’t measure either have alone both . That intend that if you test to make miniature speck by squeezing the electrons nigher in , the uncertainty in the momentum would get higher , and you ’d actually make it more likely that the whole atom gets blown aside .
Lisa and I chatted prior to this column and she expect the follow - up :
I also translate that you ca n’t bed both the position and impulse of an negatron at the same time but I ca n’t compass what force keeps it comparatively confining to the nucleus but not so unaired that it sting .
There is n’t another force at bid here . It ’s all about electromagnetism . But on small scales , electromagnetism has to include quantum mechanically skillful effects . The childlike “ like charge beat back ” and “ paired charges draw in ” Pentateuch from high school need to be tweaked to include uncertainty . There ’s also a fairly non - visceral wrench to all of this . All thing being equal , more monumental particle can be twitch more tightly than less massive ones .
Beyond simple speck , this has some fairly cool conditional relation . Particles like electron not only take up infinite , but you’re able to only put 1 of them ( two , technically , because of twisting – I ’m sure some know - it - all would have commented otherwise ) within a given book . It ’s possible to compact atoms together so tightly that the electrons are essentially asses to elbow joint . This is precisely what will happen to our sun in another 5 billion geezerhood or so when it becomes a white midget . At that spot , it will be about a million times as dense as it is now , and only about the size of the earth .
Because of quantum doubt , even gravity ca n’t squeeze a bloodless dwarf much smaller , but if you keep adding mass , eventually there ’s enough pressure to squeeze all of the electrons and proton together to make neutrons ( and a shit - ton of neutrino ) . This actually happens , whenred giants dump their mass onto ashen dwarves .
At the closing of all of this ( after a really awesome supernova explosion ) , you ’re forget with a neutron star . A neutron star play the same way of life as a white dwarf , but with the neutrons now shove against one another . Since neutron are much more massive than electron ( by about a factor of 2000 ) , they can be pack much , much tighter . To put things in position , were the sun to turn into a neutron star , it could easily fit inside Los Angeles , though I would n’t recommend it .
As an add together bonus , you might wonder what happens if you keep piling mass onto a neutron star . Eventually , you ’d get a black mess . But that ’s a story for another day .
Dave Goldbergis the author , with Jeff Blomquist , of“A User ’s Guide to the Universe : Surviving the Perils of Black Holes , Time Paradoxes , and Quantum Uncertainty . ”(Like us onfacebook , where you could see more of Jeff ’s cartoons . ) He is an associate professor of Physics at Drexel University . palpate free tosend him your questions about the existence .
Top trope byGreg Martin .
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