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Message: <blockquote data-quote="fuindordm" data-source="post: 2404230" data-attributes="member: 5435">I think Babong, PBartender and others have covered the ground here pretty well...Regarding photons, your typical photon such as the Sun spits out is a wave packet.  The particle/wave paradox really isn't that big a deal.  Do a google image search on 'wave packet' and you'll get lots of pictures of them.  Where the electromagnetic energy is concentrated, the fields look like a sine wave, and outside that region the amplitude of the wave decreases rapidly to zero.When a wave packet (essentially a little ball of energy) interacts with something on scales much larger than the waves in the packet, it acts like a particle.  When it interacts with something with sctructure much smaller than itself, it acts like a wave.  When you're in the middle ground, you can get elements of both behavior.But light is in all important essentials a wave, and its behavior can always be predicted correctly by treating it as such, even if in some situations it would be an unbearable pain in the butt to do so.Turanil's comment on time not passing at all in the photon's frame of reference is right on.  If you really want your mind blown, consider this:Imagine you're a massless mind riding a photon.  From your perspective, the ratio of time passing in the outside universe with respect to your own personal sense of time is infinity to one.  You can think of that as existing at every point along the photon's trajectory simultaneously if you want.But... the photon was created somewhere, and will be absorbed somewhere.  So it only exists for a finite time in the universe.  So 'as' you travel with the photon, you should see an infinite amount of time pass according to the rules of special relativity, and yet the photon doesn't exist for an infinite amount of time.This is the kind of thing that used to keep me up nights when I was a young, naive physics undergrad. <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":-)" title="Smile    :-)"  data-smilie="1"data-shortname=":-)" />If we're hoping for the future of space travel, keep in mind that special relativity is a *local* limit.  The difference between special and general relativity is that the latter regognizes special relativity as the rules applying to flat space-time, and that all space-time is locally flat (in the same way that we can think of the surface of the earth as locally flat, at least on an everyday human scale).  General relativity, however, allows for all sorts of strange configurations of space-time.It turns out that the 'warp fields' of Star Trek are one plausible way of breaking the light barrier.  The equations of GR allow a configuration of space-time that is flat in the middle (around a ship), contracting space in front of the ship and expanding space behind it; such a field could move faster than light globally while preserving the rules of special relativity locally.  Cool, huh?  All we need to make it work is large concentrations of exotic matter/energy with a negative energy density.As it turns out, 70% of the energy content of the universe has a negative energy density--the famous cosmological constant that is making the universe expand every more rapidly.  Negative energy densities are also observed in quantum mechanical experiments.Research progresses on this front.  We don't know yet how to harness this, or even if it can be harnessed (at quantum scales, it doesn't seem possible to create a negative energy density pulst that isn't right next to a larger concentration of positive energy).  But the SF geeks among us have reason to be cautiously hopeful.Ben</blockquote>

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