You Have Never Actually Seen Light — The Most Disturbing Idea in Physics

Comments · 196

• ZZ

  @zzaa1756 · 2 months ago

  The stars shining in the night sky teach us that the past and the present exist without distinction.

  12

• KA

  @kalimike3248 · 2 days ago (edited)

  1. With X-rays instead of light / electrons?<br><br>It still interferes, you just need much, much smaller slits.<br><br>Interference only happens when slit width and slit separation are comparable to the wavelength.<br><br>- Visible light: wavelength ∼500 nm - you can cut slits with a razor.<br>- X-ray: wavelength ∼0.01 to 10 nm. You can&apos;t mechanically make two slits that small and keep them coherent.<br><br>So what physicists do is use a crystal lattice as the slits. Atoms in a crystal are ∼0.1 nm apart - perfect for X-rays. That&apos;s exactly what X-ray diffraction is: a double-slit experiment with millions of slits. You still get bright and dark fringes.<br><br>There is one difference: an X-ray photon is much more energetic. It interacts more strongly with matter, so it&apos;s much harder to keep it from leaving a &quot;which-path&quot; trace. If anything in the environment can tell which slit it went through, even in principle, the interference washes out. That&apos;s why X-ray interferometers have to be perfect crystals in vacuum.<br><br>But if you preserve coherence, you get the same rule:<br>I = I_1 + I_2 + 2\sqrt{I_1 I_2}\cos(\Delta\phi)<br>Wave-particle duality doesn&apos;t stop at visible light.<br><br>2. With 3 slits instead of 2?<br><br>Yes, and this is where it gets really interesting.<br><br>With 2 slits, intensity at a point on the screen is from 2 waves adding:<br>\psi = \psi_1 + \psi_2<br>With 3 slits:<br>\psi = \psi_1 + \psi_2 + \psi_3<br>I = |\psi_1 + \psi_2 + \psi_3|^2 = I_1+I_2+I_3 + \text{(pairwise interference terms)}<br>What you see:<br>- The main bright fringes get <b>sharper and brighter</b><br>- You get <b>small secondary maxima</b> between them<br>- It&apos;s essentially the start of a diffraction grating. With 2 slits you get soft sine-wave fringes, with 3 you get narrower peaks, with 1000 you get the sharp lines of a grating spectrometer.<br><br>Why physicists care: The triple-slit experiment is a direct test of the Born rule, $P = |\psi|^2$.<br><br>If quantum mechanics had true 3-path interference, there would be a term that only appears when all 3 slits are open that isn&apos;t just the sum of the 2-slit combinations. Physicists define the Sorkin parameter:<br>\epsilon = I_{123} - I_{12} - I_{13} - I_{23} + I_1 + I_2 + I_3<br>If $\epsilon \neq 0$, quantum mechanics is wrong and we need higher-order interference.<br><br>Every experiment so far with photons, electrons and molecules finds $\epsilon = 0$ within experimental error. Interference is always just pairwise. Three paths interfere by interfering as pairs.<br><br>So: X-rays = same physics, harder engineering. 3 slits = same physics, sharper pattern, and a beautiful proof that quantum mechanics stops at second-order interference.

  2

• ST

  @stuartmitchell3739 · 2 weeks ago

  So do I need to get up for work?

  2

• KA

  @kalimike3248 · 2 days ago

  I want yo see the doublet slit experiment done with x-rays...or infrared, or radiowaves, or individually with Every frequency beyond visible light...

  1

• YE

  @yengEEs · 2 months ago

  What’s the final equation to put on a bumper sticker?

  6

• SE

  @senserave · 4 weeks ago

  During my college days same question what u say arrived to mind. But others told don&apos;t confuse.

  1

• DR

  @DragulaAD · 2 months ago

  This video was so good. I wish it was longer.

  2

• CH

  @ChrisWilson-wn4qc · 4 weeks ago

  Its like going crosseyed and knowing only one of the imagines are tangible in our physical reality. And the other is the split refraction of itself. Perhapes like looking in at the screen of the mind.

• CH

  @ChrisWilson-wn4qc · 4 weeks ago

  Create more then just one panel to pass,the first the slits,the second circles,and then another and see what the ending result is on the screen.

• KA

  @katon1872 · 2 months ago

  PLATO had the same ideas more than 2000 years ago. Especially in his ALLEGORY OF THE CAVE 😅

  1

• NO

  @Noro-i9i · 2 months ago

  If the could factor large numbers with quantum comps, we would know for sure.

  1

• QU

  @Queeney59 · 2 months ago

  I just love this stuff. &nbsp;I&apos;m wondering if the dark photons would appear as light in their universe and our light would appear as dark photons.

  1