sound *is* a pressure wave. what other speed should sound have?

so - yes

the ability to transfer electricity has nothing to do with the speed, with which a pressure wave is transmitted. so - super conductor behaves the same as normal conductors or isolators.

and yes - if you apply more force on an object than this object can handle, it will shatter/bend/deform/vaporize/whatever.

the universe is under no obligation to be intuitive. it just is. as a matter of fact, it is quite remarkable, that we can make sense of it in some cases at all.

if you apply force on an object - technically, you only apply that force on the outermost layer of atoms. so you push the outermost layer against the next layer, which itself pushes on the next layer and so on.

there is a maximum speed with which that force can propagate through the object. it is the speed of any pressure wave. the most common pressure wave is a sound wave - so usually, we call this speed the speed of sound. in a rigid object, sound is much faster than in air. the actual value for this speed is dependend on the material. if you have a wooden stick for example, if you push on one end, that force is transmitted through the wood with a speed of about 3500 to 5000 meters per second. which is quite fast.

if your stick is about one meter long and you push on one end, that force can be transmitted fast enough, that it looks as if that force is transmitted instantaneous. you can't push that stick fast enough to notice any delay. therefore the only force you have to apply is that to move the stick itself.

however - if your stick is considerably longer, you notice that delay between your push on the one end and the movement on the other. the stick can't move away fast enough. so you have to compress the stick - or apply the force very slowly. if you compress the stick, you have to apply extra force - you not only have to move the mass of the stick (which is now very high). if you push slow enough, you only have to compress the stick a little bit before that pressure can move through the whole stick.

now take a stick that is long enough to reach to our moon. our moon is about 400 000 kilometers away. the speed of sound in wood is about 5 kilometers per seconds. so - if you push on one end of that stick, it takes about 22 hours (!) until the other end moves. if you push the stick about 10 cm on one end, you have to compress the wood - which takes quite some force. but never mind - that stick would be so heavy that moving it at any speed is an astronomical feat.

have you ever seen a stick of wood about one kilometer long? me neither. no wonder, all of this is not quite intuitive.

you have to start with planet formation.

you have this cloud of dust. some of the dust clumps together and form - well - clumps of matter. those clumps further collect dust and grow.

all the parts of the cloud have more or less random kinetic energy - aka: swirling around in random motion. but as those parts collide, some of that kinetic energy canceles out. but it is highly unlikely, that it canceles out *exactly*. in the end, the cloud as a whole has some little "intrinsic" angular momentum - and that momentum has to be conserved. after all the parts have shed their excess kinetic energy, all that remains is this intrinsic angular momentum. this means, that if you wait for long enough, all parts of the cloud will move in the same direction - aka, rotate around the common center of mass.

in the end, your initial cloud will form a kind of disc, that uniformely rotates. in the center, the stuff will clump together further and will form the planet. stuff, that is far enough away, will stay in orbit and eventually form small moons. but the key is: they still have the initial angular momentum from the cloud - aka, the have the same rotation direction.

it's not exactly clear, how the rings around planets form. the rings of saturn are probably "fed" by water ice, that is squeezed out from some nearby moons. it could also be leftover material from the original cloud (unlikely - that orbit should not be stable enough - aka: the stuff should have fallen down on the planet or moved farther away and dispersed). of it could be small moons, which came too close to the planet and have been shredded by tital forces (see roche limit).

anyway: regardless of the exact physical process: angular momentum has to be conserved. always. if there is no external source of kinetic energy, in the end, everything in this system will move in the same direction. planet, moons, rings.

get the idea, that a photon is some kind of physical object, out of your mind. light is energy, that is transmitted over the electromagnetic field as a wave. but that wave can not take arbitrary values but only discreet multiples of a fixed value. kind of a packet of energy. and we call this packet of energy a photon. light is still an electromagnetic wave but it can only be produced and absorbed photon per photon.

there is this electromagnetic wave. and if this wave has the right wavelength (=energy density), it can excite a special molecule (the chlorophyll) in a special way that it can break the chemimal bonds between carbon dioxide molecules (co2) and water molecules (h2o) to form glucose molecules (c6h12o6) releasing some free oxygen in the process. (of course it is much more complicated than that). the chemical energy stored in glucose is higher than that of carbon dioxide or water. thats the reason, why the plant does this in the first place - glucose can be used to store energy. that energy must come from somewhere. and you guessed it: it is transformed from the light, the chlorophyll has absorbed.

the speed of the wave is irrelevant. one moment, there is no wave (just the "flat" electromagnetic field) and the chlorophyll is kind of in a dormant state. the next moment, there is a wave, consisting of - lets say, 10 packets of energy (10 photons). that energy is enough to excite the chlorophyll. it can catalyse carbon dioxide and water to glucose and free oxygen. the next moment, there is no wave anymore. aka: no more energy packets. the chlorophyll gets dormant again. photosynthesis stops.

it's not miniature balls zipping past at incredible speed! it's energy transmitted as waves. the speed of that wave is irrelevant. what matters is: is there NOW enough energy you can sap from the electromagnetic field to do something or not.

and to hammer down the obvious: if you turn on the light for 10 seconds in an otherwise dark room, there is kind of a wave front, that lasts for 10 seconds. in that 10 seconds, the electromagnetic field in direct vicinity around the chlorophyll molecule carries enough energy to do something. you only notice, that this wave arrived at the speed of light, if you compare the field strenghs of your own point with other points in the distance.

a photon detector IS a photon absorber

the photons are absorbed by the cells in your retina. basically, the energy of those photons excite some atoms. that excitation generates some electrical current. that current prompts some neurons to send an electro-chemical signal to your brain.

and yes - the photons are "destoryed" in that process (aka: it's energy is converted into another form of energy)

a photon is not some kind of miniature cannonball. it is kind of a packet of energy, that is transmitted in a wave over the electromagnetic field. take away the energy and the wave "goes flat".