Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Lewis Thomson on 11/01/2022 10:21:11

Title: How does light not make it to our eyes without hitting anything?
Post by: Lewis Thomson on 11/01/2022 10:21:11
Donald has given us another question for us to answer from the realm of space + astronomy.

"The Michealson-Morley experiment that raced a split beam of light concluded that space had no substance, that it was a void and not luminous ether. Quantum theory demands that space have a rolling boil of transient particles that NEVER interact with any permanent particle or electromagnetic radiation though they travel through this froth for billions of years because they wink in and out of existence so quickly. Of course these particles do not have gravity, or interfere with any motion. But if they are ubiquitous, and constantly produced independent of the existence of standard matter, how is it that the virtual spontaneous particle and the permanent particle don't constantly interact. For example, a photon from a distant galaxy travelling billions of years before it hits my retina just misses everything in it's path foaming up!"

What do you think? Leave your helpful answers in the comments below...
Title: Re: How does light not make it to our eyes without hitting anything?
Post by: alancalverd on 11/01/2022 11:25:28
A virtual particle is a mathematical model, not a lump of matter, so no reason for it to interact with a photon.

Quantum theory is a collection of mathematical models that can be modified to match observations: "demands" are more like "suggestions".

There are plenty of real interstellar particles, which really do interact with light,  but plenty more photons.
Title: Re: How does light not make it to our eyes without hitting anything?
Post by: Eternal Student on 12/01/2022 13:12:56
Hi.

Donald has given us another question for us to answer from the realm of space + astronomy.
   It might be worth putting this in the Physics and Astronomy section.  It doesn't really matter but more experts in QFT might see it.

   Overall I have to support Alancalverd:    The idea of particles popping into and out of existance is just a useful visualisation of what is happening in some quantum fields.   Virtual particles are not like ordinary particles.

   
Of course these (virtual) particles do not have gravity, or interfere with any motion.
   I'm really not sure about this.  Where were you or Donald getting this information from?
   There isn't a good quantum theory of gravity we can connect straight to Quantum field theory.  So, I'm not sure how this conclusion could have been reached.
    If a virtual particle is interpreted as some temporary localised energy in an underlying quantum field and the classical field theory of General Relativity applies -  then this localised energy density should contribute to the stress-energy tensor.   Hence, the curvature of space, or "gravity" would be influenced by the presence of the virtual particle.

For example, a photon from a distant galaxy travelling billions of years before it hits my retina just misses everything in it's path foaming up!"
   It doesn't have to miss.  It just doesn't interact much.
 
Best Wishes.
Title: Re: How does light not make it to our eyes without hitting anything?
Post by: yor_on on 20/01/2022 14:29:27
Heh :)

It's a luminous 'field' in some models, needing no propagation but still a time line giving it the expression of propagating.