Here is one I expect to be very controversial...
On a solid wood electric guitar, the tone is in the tone wood.
The sound generated by the pickups, if the pickups are acting properly has little or nothing to do with the wood.
The iron in the string disturbs the magnetic field created by the magnets which in turn generates a tiny electric current in the coil. Disturbing a magnetic field is the most common way to generate electricity and it's how your power company does it.
The wood is not magnetic and has nothing to do with this. You can't generate electricity with 'tone wood' and a properly functioning pickup is not a microphone. Take the strings off, shout into the pickup as loudly as you can and see if your voice is coming out of the amp.
The tone is affected by a lot of things, mostly the pickup design, after that string composition, string height, picking technique, fretting technique, scale length (to a lesser effect), and anything that effects the vibration of the strings in that magnetic field. A solid guitar might vibrate a bit, but probably a thousandth of a percent as much as the strings, and I leaned in electronics that anything less than 10% is for all practical purposes the same.
OK, I know this is controversial, so I'm ducking for cover.
Insights and incites by Notes
You are not correct but don't be afraid!!
No, it is not controversial at all. The facts are known by many. There are always those who exaggerate these facts and their significance, regardless of topic. Many grains of salt need to be taken.
The wood IS a factor but it is one of many and usually not the most prominent one unless the guitars are otherwise identical.
Ive been playing, repairing and even building guitars for over 50 years (I'm 65 and started playing when I was 14).
There are MANY factors that affect the tone of all guitar, some of them are subtle but they do exist. As a beginning point I will mention all of the headstock tuners that work by picking up the vibrations of the strings at the end of the headstock. They could not do that if the neck material was not capable of transmitting vibration. Transmitting vibration indicates that there is resonance.
"Resonance" is simply another way of saying "robbing the strings of energy". A Gibson SG is much more resonant than an ash-bodied Telecaster with a maple neck. You can put your hand on any part of an SG guitar, strike the low E string vigorously and you will feel that vibration. This resonance does vary by frequency and different pieces of wood will affect those frequencies differently, some certainly less than others. It can be subtle to the point of absurdity, UNLESS somebody plays really loud - then it can become noticeable. Unlike us sensible old-timers, lots of players crank up to ridiculous levels. I did, decades ago - Mesa half stack!!!
There are absolutely other factors at play, which muddies the waters considerably. The design, tolerances and materials the bridge is made of certainly make a big difference in the tone of a guitar. So does the strength of the magnets in the pickups.
Let's talk extremes to exaggerate my point. Take a banjo and a Les Paul. The banjo is extremely "resonant", it robs the strings of energy pretty efficiently. It is loud and has very little sustain. The frequency response is quite uneven. A Les Paul (depending on the bridge used) is not very resonant and the strings ring longer and more evenly since specific frequencies are not drained more than others.
The bridges I mention on a Les Paul? The original Tune-O-Matic bridges used a "spring" (bent piece of guitar string as far as I can tell) to keep the individual, adjustable saddles from falling out of the bridge when a string breaks. You have a contact point with a fugitive thread on one end and "sort of held in place" on the other. Guess what? String energy is lost to the saddle assembly "rattling around" in it's housing. Later Les Paul bridges were made by Schaller (and now by who knows?) and secure the saddles tightly. Resonance is diminished. This whole "locking bridge" thing that appears to be recent? I've got an 86 ES 335 with a rare Schecter Tri-Lock bridge - each saddle has opposing screws adjusted from each side and is FIRMLY locked in place. I modified it slightly and it has been bolted in place with intonation set for 10-46 strings since about 1989. I've never adjusted it, still perfect. That made a significant increase in sustain and eveness - certainly aspects of tone and NOT just the pickups.
The floating bridges of vintage Fender Jazzmasters and Jaguars are tone-suck monsters, so are the cam operated Kahler vibratos. The first iteration of the Floyd Rose vibrato system did not have fine tuners and it provides as close to a pure string tone as a vibrato bar can muster. Lots of bridges fall somewhere in between.
If you have a vintage Strat or one of the newer ones with the Vintage Noiseless (STRONG magnets), I can make your guitar unplayable by raising the pickups up to the point where the magnetic field is so strong that the part of the string over the pickups is "dragged" to a lower pitch. Now when you play higher on the neck you will hear "wolf tones", a wrong note fighting with the right note. It is not pretty at all and yes, that IS the pickups making a change for the worse. Lower them down or switch to low magnetic field pickups like Lace Sensors or EMGs and the problem is solved.
The neck joint, where and how the headstock joins, the fretwire and fingerboard wood, the thickness of the body and the routing (including it's location) all make subtle differences. The string choice can make quite a difference depending on choice.
Ignoring any of these factors and focusing just on the woods used is a fallacy, I agree. Still, if you change the body of a P-Bass from ash to alder (I've done this a few times and in both directions) it absolutely will change the tone of the instrument.
So, there you have it. Been there, done that. Cheers, Kuru