[Pseudoscience-is-malarkey (OP)]

I've always wondered...

[Bored chemist]

Yes.

[Colin2B]

I've always wondered...

it used to be the standard way, usually the harpsichordist would indicate the start and the rest would follow his lead, timing etc.

[alancalverd]

A sample of conductor jokes

As long as he waves in time with the music, we let him announce the next number.

A would-be drummer who can't manage two sticks.

..... etc.

And one from a conductor, aimed at the bass section (mostly me): "Gentlemen, the object of rehearsal is for me to interpret the composer's aspirations, not for you to consolidate your mistakes."

[Bored chemist]

Just to wind Alan up...
"Can an orchestra operate without a conductor?"
How do you think they invented jazz?

[Petrochemicals]

I think a super conductor  would improve on the performance even more (of the orchestra)

[marklivin]

It seems to me that an orchestra can function without a conductor, but the quality of the musical product will be very low.

[Colin2B]

It seems to me that an orchestra can function without a conductor, but the quality of the musical product will be very low.

Most early music orchestras performed without a conductor, the quality was not reported to suffer.
I have seen a number of performances without a conductor and I think the quality was excellent and they received standing ovations.

[alancalverd]

The orchestra was on tour. On the second day, the conductor went sick with flu.
Quick discussion and the second viola said "No problem. I played the same program with Harry last year, so I'll conduct until he recovers."
The tour went smoothly, and on the last day Harry was well enough to conduct the final concert.
Second viola took his seat, and the first viola said "Where the hell have you been for the last two weeks?" 

[Colin2B]

There are many things in life I can be grateful for. One is that I never took up the viola.

Viola player says to pianist. “I like that piece you played earlier with the trill at the beginning”.
Pianist, “I don’t know a piece with a trill at the beginning “
Viola player “Oh yes you do, it goes (hums opening of Fur Elise)”

[Bored chemist]

A significant factor is the size of the orchestra.
If it's small the time taken for one side of it to hear the other is short so they can keep in synchrony.
If that delay is long the players tend to "wait for the others to watch up" and so the music slows down.
If they watch a conductor the delay- is about a million times less.

[Colin2B]

A significant factor is the size of the orchestra.
If it's small the time taken for one side of it to hear the other is short so they can keep in synchrony.

Yes, I was going to mention this.
In a good orchestra without conductor the players sync from the harpsichord, organ or piano which is placed centrally or at least visible as in the case of the organ, this is usually the lead. This was how Bach and Handel would have worked. Either that or the lead violinist would act as coordinator, I believe that’s how the Paris opera worked. It was only around the 19C that we get the composer acting as orchestrator (although I’ve heard the words autocrat used) and later on acting as an interpreter of the music. I think in the modern sense, this is where the conductor can add value, through the interpretation of the music and knowing where to give emphasis.
My daughter has worked with a number of conductors who have been described as useless, in this case all the players watch the lead violinist, looking for the downbow.
Even with a conductor the players have to watch up to see the downbeat, but a good orchestra, well rehearsed will only be using the music as aide memoir.
Worth watching a good quartet or consort to see how often they will glance towards the leader who gives a just perceptible nod as they set off into the next section, the rest of the time they will be glancing at each other’s arm movements.
Interesting that they haven’t yet started using the in-ear foldback that will be familiar to Alan. I have offered to lend mine, but they haven’t taken it up!

[alancalverd]

I've never used any artificial aids. Jazz bands are usually led by the trumpeter because it's the only instrument that can be played with one hand, but I spent many years watching the very expressive right bum cheek of a boss who played trombone. The best bands, of course, lean back and swing around the bass - the essence of cool.

I attended a string quartet recital that include John Cage's silent 4'33". They all had scores in front of them, marked with bowings! I asked the leader about the sheet music. He was very insistent that the bowings were his interpretation, and whilst they rehearsed from photocopies, Performing Rights insisted that they only took printed copyright sheets onto the stage. 

The size of an orchestra posed a problem in the past. Composers have a composite sound in their heads, but it doesn't translate properly because the first violins are on one side, brass at the back, etc. Edison solved the problem by making all the sound come out of one hole, and recording engineers could balance volumes and remove echoes by using multiple microphones....until some idiot ruined it all by introducing stereo!

[alancalverd]

a good orchestra, well rehearsed will only be using the music as aide memoir.

Depends on the gig. A lot of session work is sight reading of stuff that was composed last night. I think one job where a conductor is essential is film music, where the stick-waver is watching the film projected behind the band.

[olegmayami]

I think it would have been hard for them to play it straight. It would have taken them more time to prepare

[alancalverd]

Shouldn't be a problem for a pro band. The first performance of Holst's "Planets" suite took place 4 hours after he finished writing it. That's the advantage of a conductor - you just play the notes according to his gestures, and it sounds coordinated.

It's rare for a conductor to rehearse an entire piece: life is short, so they often just work through the bits where they want a particular interpretation that isn't obvious from the score. Likewise with small jazz bands: you assume everyone can play the tune: rehearsal is about relative dynamics and the order of solos.

That said, I've been told that sight reading is a very British obsession, which is why so much session music is recorded in the UK - "one take from page to disc" is unheard of in some other countries.