This page:


Discusses the error Neil deGrasse Tyson made when talking about electronic transitions (video included there). Tyson clearly said in his Cosmos series that electrons disappear from one level and appear in the other one.

The guy in the page discusses that this is wrong, because there is no proof of that, and because it breaks simplest rules of relativity, and because it contradicts the simplest quantum model.

Is his argument correct? And why would Tyson do such a horrible mistake?

For more information please visit the link.

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    $\begingroup$ And why would Neil Tyson do such a horrible mistake? Oversimplification. Btw, I've skimmed article and there is a mistake: the wavefunction is not zero only at infinity. $\endgroup$
    – jinawee
    Aug 3, 2014 at 15:11
  • $\begingroup$ Perhaps this page en.wikipedia.org/wiki/Atomic_electron_transition will help clarify "reality" ? $\endgroup$ Aug 3, 2014 at 15:12
  • $\begingroup$ @jinawee Where else? $\endgroup$ Aug 3, 2014 at 15:20
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    $\begingroup$ For the hydrogen atom in the ground state, the wavefunction is zero at the center of mass. In general, you would have to use numerical methods, see this chart: teacher.pas.rochester.edu/PHY237/Exams/Exam2/Exam2_files/… Anyway, I don't think "to teleport between energy levels" has sense in modern QM, since energy levels aren't identified with any position. $\endgroup$
    – jinawee
    Aug 3, 2014 at 15:24
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    $\begingroup$ @jinawee: the graphs you show are the probability of finding the electron between $r$ and $r + dr$, which is $P(r) = \psi\psi^*4\pi r^2$. The wavefunction is not zero at $r = 0$. For example the $1s$ is $\psi(r) = Ae^{-r/a_0}$ and this is actually a maximum at $r = 0$. $\endgroup$ Aug 3, 2014 at 16:07

2 Answers 2


Tyson claims that an electron disappears from one orbital and appears in another and claims that this is like going from the second floor of a building to the fourth floor without existing in between. This doesn't actually happen. What happens instead is that each possible state of the system has a continuous amplitude associated with it. In a transition from state 1 to state 2, the amplitude of state 1 continuously decreases over time while that of state 2 continuously increases. These states overlap in space and so there is no mysterious magical mystery about an electron hopping from one place to another or anything like that. There is just continuous evolution of continuous amplitudes of the discrete set of states in which the electron can be found upon measurement.

The confusion about this kind of issue is a result of the mess that is usually made of discussing how quantum mechanics should be understood when it comes to measurement. The standard story is that the state of a quantum system jumps or collapses into one of the possible outcomes on measurement, but this is false. A more accurate description goes like this. A measurement has to create information that can be freely copied so that where is was previously present only in one system it latterly becomes present in many. It is not necessarily true that the system that was originally measured has its state copied. The state can be wiped instead, it can be reset to some default state. But the measurement result itself has to be able to be copied, otherwise you can't discuss it because to know about it you have to copy it into your brain. And information that can be copied in this way is discrete and the copying process prevents interference, see


Even this paper is not as clear as it should be. The author should state that in fact the state doesn't jump or collapse, it just evolves according to the appropriate equations of motion. The observer is often present in multiple states after the measurement but he can't experience any state other than the one he is in because the copying process prevents interference between the different versions of the measurement result.

See also


  • $\begingroup$ I can't follow your argument following "A more accurate...". But the argument is probably too long for a short paragraph. And I haven't read the papers. But: is it not true that the time evolution you talk about refers to an ensemble of identically prepared systems? The argument does not apply to a single atom. My understanding, which could be just wrong, is that no time evolution can be described for a single atom. (?) Saying that it's mysteriously instantaneous is the best we can do. (?) $\endgroup$
    – garyp
    Sep 9, 2014 at 12:54
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    $\begingroup$ No. The time evolution describes the evolution of a single system. The square amplitudes can in general only be measured by measurements over multiple systems. However, there is no explanation of a single particle interference experiment in which each particle only goes through one slit at a time, see "The Fabric of Reality" by David Deutsch, Chapter 2. $\endgroup$
    – alanf
    Sep 9, 2014 at 14:55
  • $\begingroup$ +1 Good answer: I gave a quantitative version of your answer for a very like question to this one; see physics.stackexchange.com/a/86486/26076 $\endgroup$ Sep 15, 2014 at 12:13
  • $\begingroup$ Thank you for putting forward the time evolution theory for the transition between quantum states. I believe it is the correct theory but I am routinely and massively downvoted when I try to make that case. One of the consequences of the time evolution picture is that there is an oscillating charge distribution during the transition. I claim that all the ordinary thermal interactions between matter and radiation (including the black-body spectrum) are explained by applying Maxwell's equation to that oscillating charge. Do you agree? $\endgroup$ Oct 4, 2016 at 18:54
  • $\begingroup$ @MartyGreen No. Maxwell's equations don't include quantisation. Also, the black body spectrum is explained by quantisation. Read a basic book on statistical mechanics. $\endgroup$
    – alanf
    Oct 5, 2016 at 8:31

Your questions reminds me of the movie "a serious men" by the Coen brothers (you should watch it regardless of the main character being a college physics professor). As some of the comments said, it is an oversimplification or a much more complex phenomenon. The only way to get some idea of what is happening is to understand the equations of quantum mechanics. But even if you do, there still is the problem of interpreting what they really mean. And not all physicists agree on that. That is a subject of study in foundations or philosophy of physics. There is still no agreement in the physics community on how to interpret the meaning of the equations of quantum mechanics. Much less in how to explain them to the general public!

  • $\begingroup$ Balogni! “If you can't explain it to a six year old, you don't understand it yourself.” ― Albert Einstein $\endgroup$
    – eromod
    Dec 31, 2017 at 15:54

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