Roger Penrose asked what anesthesia actually switches off. Last month a hospital team from India showed a signal on 40 surgery patients that is there while they're awake and gone the moment they go under, and it sits where his theory said to look.
This video follows what happened to that theory in the autumn of 2026: the lab result with Penrose's own name on it, the single-celled animal that goes under the same way, Google's quantum chief and his fruit flies, the day Penrose and his co-author disagreed on stage about building conscious machines, and the recordings of what the brain does after the ventilator is switched off.
Clips: Roger Penrose with Lex Fridman and Curt Jaimungal, Stuart Hameroff with Danny Jones and at the Science of Consciousness conference 2026.
0:00 The Mystery of Anesthesia 1:58 A Breakthrough at Princeton 4:05 The Unlikely Partnership 5:29 Quantum Experiments with Fruit Flies 10:24 The Final Moments of Awareness
And when you're thinking about general anesthetics, it's very specific.
These things turn consciousness off.
What the hell do they do?
That's Roger Penrose, a Nobel Prize winner.
And the doctors who give those drugs say they don't know.
Last month, a hospital team from India showed what
its probe picked up on 40 surgery patients.
A signal that's there while you're awake
and gone the moment you go under.
It sits where Penrose's theory said to look.
And his theory says that signal doesn't only switch off.
The monitor in that operating room never saw it.
The machine an anesthesiologist watches during surgery turns
your whole brain into one number
between 0 and 100, read off a strip on your forehead.
The team from Bhopal went looking in a place that monitor can't hear.
Their probe picks up signals far too fast for it,
millions of beats a second,
and in a patient who's awake, it finds a pattern of three peaks.
The propofol goes in, and the three peaks disappear.
What's left on the screen is bursts and a flat line.
The team wants to turn that into a new kind
of monitor for how deep under a patient really is.
That fast range is where Penrose's co-author says something inside
your brain cells is humming.
He's Stuart Hameroff,
an anesthesiologist who's on that team's earlier paper,
and when he's asked on camera how anesthesia works,
his answer is, nobody knows for sure.
He wrote the theory with Penrose 30 years ago,
the one that says those drugs reach
something inside your brain cells.
If you've ever been put under for an operation, that was done to
you, by someone who couldn't have told you what it was,
and the monitor beside you was following
Following something it has no way to look at.
For most of those 30 years,
physicists had a reason to wave all of it away.
Max Tegmark had worked out that a living brain
is far too warm for anything like it.
And in 2009, two more papers called the idea untenable
and not a feasible explanation.
The answer came out of a lab at Princeton in January 2023.
Chemists there took the protein tubes
that run through the inside of your cells,
put energy into them with light, and measured how far it traveled.
It went farther than the accepted theory can explain.
When they added two anesthetics, it dropped.
The drugs that switch
a person off had dimmed something inside those tubes.
One of the authors of the Princeton paper is Roger Penrose,
which isn't where you'd expect to find a man
who got his Nobel Prize for black holes.
Hameroff signed it too, and last month, on a stage in San Diego,
he gave his answer to the man who'd done the sum.
So Tegmark can go to hell.
The same target turned up somewhere stranger this October,
in a report from a lab at Wellesley College.
They had new evidence that those tubes are what anesthetics act on,
in mice, and in a creature made of one single cell.
It has no brain and not a single neuron,
and still the lab points at the same target.
Those tubes aren't special to that creature, or to your head.
Penrose himself points out they're in almost every cell you've got.
The part of your brain that holds most of its neurons
is the part at the back that keeps you
balanced, and Penrose says that,
as far as we know, it's entirely unconscious.
All those cells are firing, and there's no experience in it.
If he's right, the switch your anesthesiologist flips
was never about brain cells firing,
because it sits in a piece of machinery that a single cell already has.
But Penrose didn't find that machinery himself.
He published a book in 1989 arguing that a mind can't be a computer,
and he reached the end of it without knowing where
in the brain his idea could possibly happen.
So I sort of invented something out of my hat
which I didn't really believe,
and I finished the book slightly dishonestly.
A letter turned up from an anesthesiologist in Arizona
who'd read the book and thought he knew
the place. Penrose remembers his first reaction to it as,
oh, not another one of those.
Hameroff was on his way to England anyway, and he invited himself over.
The two of them talked for hours,
and by the mid-1990s the theory belonged to both of them.
Hameroff told last month's conference what he'd
do if it's ever proven wrong,
which is go back to being an anesthesiologist.
He'd spent his working life switching people off
and bringing them back,
and the part of the theory he cares about most has nothing
to do with an operating room.
Penrose went after the physics.
He was one of the authors of an experiment this September that
made the first direct measurement of how gravity acts
on a falling object in a quantum state.
He gave that San Diego conference his account of where his idea stands.
Another physicist had reached the same formula Penrose did
and drawn further conclusions from it,
and those, Penrose said, turned out to be wrong in an experiment.
His own version depends on something very peculiar about time.
He called proof of it a long way off.
But Hameroff told the same conference,
we're on the right track.
And three days earlier, a man from Google had stood up there
and shown he wasn't waiting for either of them.
His name is Hartmut Neven.
He runs Google's quantum computers,
and his plan is to connect a human brain to one of them.
On the 13th of October,
he walked that room through an experiment with a syringe.
You put fruit flies in the syringe, 40 at a time,
with xenon, a gas that puts people under too,
and push the plunger down until the pressure inside
is about three times the air around you.
In his words,
When the flies all fall to the ground, they're anesthetized.
You pull it out, which is amazing,
just in seconds they're buzzing around again.
A fly can be switched off and back on with a thumb.
Xenon is a gas that barely reacts with anything.
It's not supposed to go under proper chemical reactions at all,
as Penrose puts it, and
it still switches a person off.
A study in mice, years before,
had found that some kinds of xenon atom were weaker anesthetics
than others, even though chemically they're the same gas,
and a stack of theory papers
had been built on that one result.
Nevin's flies went the other way.
His warning about those papers was, be careful,
don't take that to the bank just yet.
A second test used laughing gas,
the same gas a dentist gives you, in two versions,
and the only difference is that one is made
with a slightly heavier kind of nitrogen.
It should do the same thing to a fly, and it didn't.
So the means are about a factor of 2.5 different.
The odds against a fluke, he said, were off the charts.
A little extra weight in an atom isn't supposed to matter to a drug.
If it changes what an animal does,
then whatever the gas grabs isn't ordinary chemistry,
and something that fine can be turned up and down.
Nevin's phrase for where his work is headed is,
sculpting conscious experience sort of on demand.
The recording of that talk is online,
and in early November it had 194 views.
Nobody had waited for that result.
In Florida, a year and a half before,
a company had already put a four-legged robot in front of an audience
and handed its next move to a quantum computer.
About twice a second the robot asks,
and the quantum machine picks one of 32 things for it to do.
The company says it's looking for signatures of consciousness.
There's now a robot that waits for a quantum computer to tell it what
to do next, and a company watching to see whether anybody's home.
The last day of the San Diego conference was the 16th of October
and that's when Penrose was asked
whether a machine can be conscious.
He's 95 now and he joined on a screen instead of in the room.
One of the other speakers told him,
I thought you were going to be here in person.
The panel's question was whether AI is conscious.
Penrose didn't soften it.
I would certainly say that this idea
that a computer could become conscious
is in my view completely wrong.
Computers aren't, he said, and they never will be.
He didn't spare Nevin's machines either.
So I would argue that even what they call
a quantum computer now would not
have any chance of becoming conscious.
A philosopher on the panel asked him whether
the quantum computer wasn't
a counterexample to your view.
No, I don't think so. I don't see why.
And about the AI people already use,
he told the panel, I think there is a danger in that.
That's the man who started the theory,
telling a room that Google's machines have nobody inside them,
and neither does anything else built so far.
His co-author was sitting on the same panel,
and he wants something else.
And now we know that AI without conscious can
be dangerous and threatening,
with these jailbreaks and all this and that.
So maybe we need conscious AI.
A colleague of his, he told the panel,
is building a quantum computer for the Indian government.
But Penrose had named the danger in AI a year earlier
when the chatbots came up.
I find it scary in the sense that really
because people believe it's conscious
and probably it will do things.
He's afraid of the machines with nobody in them
and of the people who'll believe there is.
About people, Penrose keeps returning to one experiment
done on a patient during brain surgery.
Someone touches the patient's finger,
and a quarter of a second later stimulates the brain directly.
The patient feels the second thing, and never the first.
How can you unfeel something which you should already have felt?
Penrose's answer, in another talk, was that
it seems the time is all messed up in some peculiar way.
That it goes almost as though it's retroactive,
and maybe it is in some sense.
In his theory, the moment you feel a thing,
and the moment the clock says it happened,
don't have to be the same moment.
Even the moment a person stops feeling is harder
to pin down than a clock makes it look.
Every switch so far is one you come back from,
and there are recordings of the other kind.
They come from Michigan,
where a team published the brain recordings of four patients in 2023.
All four were in comas, and the recordings were taken
while their ventilators were removed.
In two of the four, within seconds of the air stopping,
the back of the brain lit up with the
fast activity that, in a healthy person,
goes with being aware of something. Their oxygen was running
out, and that activity came after
the one thing keeping them alive was taken away. None of the
four survived. The team's caution was that it could
be nothing more than a brain failing.
Hameroff describes the same pattern as a trace that goes flat
and then there's this burst of
activity lasting from seconds to a couple minutes,
and he reads it differently. His version starts
when the blood stops reaching the brain
and the tubes in those cells stop getting what they need.
To him, the consciousness is information,
and at that point, it goes out into the universe.
Yes, it leaks out, but it stays entangled as a self.
So it could be distributed, maybe holographically, in the universe,
but remaining entangled as an entity, as a quantum soul, if you will.
He's also said, about his own death,
I don't worry about dying. I really don't.
And it wasn't only two patients.
Doctors in Washington, back in 2009, had seven dying
patients wearing the same kind of monitor that's used in surgery,
the one that puts a number on
how conscious you are. The monitors were only there
to make sure those patients stayed comfortable.
Their blood pressure fell away to nothing. And then the number went up,
and the doctors wrote that it approached
levels normally associated with consciousness.
They were standing at the bedside of people
with no blood pressure, watching the reading for
awareness climb.
It's the same number an anesthesiologist uses to decide you're far
enough under to be cut.
If Penrose is right, the thing the gas switches off in surgery and the
thing that climbs after the blood pressure is gone are one
and the same process. In those last minutes
it's still running, at a point where
the room has stopped treating that person as someone who can
You can feel anything.
That's a room you've stood in, or will,
and one day, it's the room you'll be lying in.
The probe from Bhopal, the one built to pick that process up,
has so far been reported on 40 people who were having an operation.
Penrose asked what those drugs turn off,
and the recordings from Washington and Michigan
are what it looks like coming on,
with the air cut off and the blood pressure gone,
in patients who never came back.