Today I offer two small essays concerning light. The first – In the Beginning – weighs in at 315 words. The second, a bit more ambitious at 761, is entitled:
When whimsical particles of light collide.
In the Beginning
To begin with: Imagine that the universe gradually stops expanding and eventually collapses to what it was before the Big Bang. The universe will, in this imagining, return to its point of origin - - which I’ll call Point Zero. What will happen to that vast amount of light which has been radiated by all those stars for all this time? Think about the light which we’re now detecting from the (most?) far-flung edges of the universe. Did the objects which radiated that light also send light in the opposite direction – send it away from the center of the universe? Of course.
As far as it is possible to be from the center of the universe, light has travelled that far. Light and nothing else.
Consider this: After the entire mass of the universe collapses back to Point Zero, all of that far-flung light will bend back and head straight for Point Zero. Why? I’m not sure. It could be gravitationally-inspired or even divinely inspired.
Suppose all the matter in the universe returns to a single point and just waits. Let’s also say that this single point of matter can’t re-explode into another Big Bang. Why not? Since we’re not sure how the first(?) Big Bang happened, who can be assured that a second(?) One is possible?
Meanwhile, all that light (all that far-flung, distantly-radiated light) races back through the Void and bombards that single point of matter sitting at Point Zero. This bombardment will be from every direction: wave after wave after wave … assaulting Point Zero. Do you suppose all that light will have enough energy to re-explode that single point of matter into another Big Bang?
There’s a hidden meaning behind the expression “Let There Be Light.” This expression is incomplete. It should read: “Let there be light cast upon that single point called home, for only light can set us free.”
When whimsical particles of light collide
My question of the day:
Off and on over the decades, I’ve wondered what happens when photons collide – which of course they do all the time, but humor me on this one : -)
Some definitions (keep these in mind as I expound my whimsy):
According to Wikipedia*:
“…a photon is an elementary particle..the basic “unit” of light…[and] the photon has no rest mass”
[Comment: No “rest mass,” eh? No problem: Since photons (that is, particles of light) don’t even exist at rest, the whole concept of rest mass doesn’t seem to apply to light, for light is never at rest.]
According to answerbag**:
“…a photon is at least a Billion-Trillion times lighter [than an electron]! (most likely its mass is exactly zero)”
[Comment: What you mean by “most likely,” White Man?]
According to many sources: Light is a phenomenon that exhibits the properties of waves and particles – this is known as the wave-particle duality.
Increasing the mass of particles is the key
The machines crudely known as atom smashers (more to the point: particle accelerators) do just that. After streams of particles within an atom smasher (for instance, electrons) have been accelerated to near the speed of light, they’ve substantially increased in mass. These extra-massive electrons are then bombarded into target atoms, thereby disintegrating them into their component parts.
The extra mass which is gained by the process of acceleration is the key. In fact, acceleration is the key. The reason why nothing can travel faster than (or even as fast as) the speed of light has to do with the upper limit this increase-of-mass phenomenon imposes on physical reality.
When an object starts to accelerate – even slowly at first – it gains mass (by the way, I never understood how that worked). The faster an object can be made to move, the more massive it becomes. If you could accelerate an object so that it actually reached the speed of light, it would have to have infinite mass (which is more mass than that of the entire universe).
Which of course means, no object could ever hit light speed due to this upper limit.
But…photons (which are particles, right?) are already moving at the speed of light, so if they have any mass at all, that mass must be infinite (unless it’s special mass – I jest). [I know, I know…this sentence must stand as proof that photons have absolutely no mass when in motion, which further verifies what we already know: photons have no rest mass.]
However, in order to assert that light is in some way a “particle” yet has no mass, invites us to the realm where it’s possible for particles (other types, above and beyond photons) to “exist” without mass (or, to put it crudely, stuffness). If that can be possible, then one is forced to ask: “Just what exactly is something that has no mass? Can anything without mass be said to have any is-ness whatsoever?”
My crude experiment
I took two flashlights and aimed them at each other, turning them on. I thought about all those photons smacking into each other at the speed of light, each one having all the mass that speed implies. Since accelerated electrons moving near light speed can actually disintegrate atoms, shouldn’t these photons disintegrate each other if they suffer head-on-collisions at this highest-possible-speed?
Guess not….turning my two flashlights on didn’t smash photons and vaporize me. There was no sudden release of a tremendous amount of energy similar to the kind of energy rush you get when atoms are smashed (as in a nuclear weapon).
But I thought, “Wait a minute. What if we aimed two laser canons at each other and opened fire?” Of course, the timing would have to be exquisite. But what if?
Just thinking…
Light holds a very special place in my heart. In a literal sense, a photon of light “pops” into existence when an atom is excited to a higher energy level. First it doesn’t exist, then it does exist. Also special because God said, “Let there be light.” First there was no light, then there was. Interesting, in and of itself.
As for any wave-particle duality, maybe a photon “shuttles” back and forth between these two identities and does this so rapidly, even if two photons collided, there wouldn’t be any tremendous release of energy due to photon-smashing unless both happened to be in particle mode. If you talk about the odds of that happening, I suppose far greater within a star than in the void of space or even here on earth.
Steven Searle for US President in 2012
“When the sages spoke of ‘the lightness of being,’ maybe they weren’t referring to the aftermath of a diet or a lightheaded giddiness.”
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