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I'm asking this question because atoms can definetely not travel at the speed of light.

Atoms have electrons orbiting them at a speed very close to the speed of light, so, is it really possible for anything(macro objects) to travel at the speed of light?

P.S. : Is there any word for this condition where an atom loses electrons due to translatory motion?

abrn2195
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    "Atoms have electrons orbiting them at a speed very close to the speed of light [...]" Where'd you get that exotic statement? – noah Feb 24 '21 at 09:31
  • I've learnt in school that the speed of electrons is equal to the speed of light, but it usually is barely shy of that though they don't really get to those speeds – abrn2195 Feb 24 '21 at 09:32
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    Electrons don't actually orbit anything. In atoms they don't travel at near-$c$ either, those points are plain wrong. – Gert Feb 24 '21 at 09:53
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    Short answer: no massive (=with mass) particle or object can travel at the speed of light. – jng224 Feb 24 '21 at 09:54
  • How fast do electrons travel in an atomic orbital: https://physics.stackexchange.com/questions/20187/how-fast-do-electrons-travel-in-an-atomic-orbital – Gert Feb 24 '21 at 09:57
  • @Gert I tend to disagree. In heavy atoms core electrons need relativistic treatment. That can only be because they move at relativistic speed. – my2cts Feb 24 '21 at 10:04
  • @my2cts You are right but I'm answering the OP's query: for the most part electrons in atoms do not travel at $c$ or close to it (which the link clearly shows) Relativistic treatment is only needed for the inner electrons of the heavier atoms. – Gert Feb 24 '21 at 10:10
  • @Gert I agree with that. Valence electrons and ionisation energies are nonrelativistic. As to valence electrons the OP statement is incorrect. Only deep core electrons of heavy atoms are relativistic but surely he was not thinking about these. – my2cts Feb 24 '21 at 10:15
  • @Gert I just added a more complete answer to the question on speed of electrons in atoms; I would say you have understated the role of high speeds here. Even outer electrons may attain a few percent of the speed of light, and inner electrons attain a large fraction of it for most elements. – Andrew Steane Feb 24 '21 at 12:22
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    @AndrewSteane Atoms have electrons orbiting them at a speed very close to the speed of light, I take this to mean: "atomic electrons generally move very close to $c$" and that's incorrect and that is what I addressed. This is my last word on this as the focus of the OP's question isn't that. – Gert Feb 24 '21 at 12:54

2 Answers2

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Photons (obviously) travel at the speed of light in vacuum. Any other particle with zero rest mass (such as the hypothetical graviton, if it exists) would also travel at the speed of light. Nothing with non-zero rest mass can travel at the speed of light in vacuum. However, particles can travel at or faster than the local speed of light in media such as water - see this Wikipedia article.

gandalf61
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Nothing with rest mass can attain the speed that light travels at in vacuum.

Andrew Steane
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