One of the great unknowns of our age, possibly the greatest, is what determines the boundary between quantum mechanical behavior and classical (GR) behaviour. Chemistry bridges the size scale between the small quantum behaviour and the large classical behaviour. So I’ve been waiting for chemists to announce equations that determine whether a given system will be behave according to QM or GR, the boundary between the two.

It hasn’t happened. In 40 years of looking, I’ve only seen one article, probably in Scientific American, that deals with measuring the interface between QM and GR, and even that didn’t give details. The article was about molecular rotors.

In a molecular rotor, a relatively small part of a larger molecule can rotate into various orientations relative to the rest of the molecule. In classical behaviour, the energy of the system is given by
E=L²/2I
where L is the angular momentum and I is the inertia. In quantum behavior, the energy of the system is given by
E=(h/2π)²;J(J+1)/2I
where J is the rotational quantum number. By observing the energy of the system, chemists have directly probed the boundary between QM and GR.

It turns out that there is no smooth transition between QM and GR behaviour. Instead, the transition is a statistical one. At a given molecular size, the molecular rotor has a 50% chance of behaving exactly according to QM and a 50% chance of behaving exactly according to GR.

Do you know any more about this, about the probability distribution that separates QM from GR?

mollwollfumble said:

One of the great unknowns of our age, possibly the greatest, is what determines the boundary between quantum mechanical behavior and classical (GR) behaviour. Chemistry bridges the size scale between the small quantum behaviour and the large classical behaviour. So I’ve been waiting for chemists to announce equations that determine whether a given system will be behave according to QM or GR, the boundary between the two.

It hasn’t happened. In 40 years of looking, I’ve only seen one article, probably in Scientific American, that deals with measuring the interface between QM and GR, and even that didn’t give details. The article was about molecular rotors.

In a molecular rotor, a relatively small part of a larger molecule can rotate into various orientations relative to the rest of the molecule. In classical behaviour, the energy of the system is given by
E=L²/2I
where L is the angular momentum and I is the inertia. In quantum behavior, the energy of the system is given by
E=(h/2π)²;J(J+1)/2I
where J is the rotational quantum number. By observing the energy of the system, chemists have directly probed the boundary between QM and GR.

It turns out that there is no smooth transition between QM and GR behaviour. Instead, the transition is a statistical one. At a given molecular size, the molecular rotor has a 50% chance of behaving exactly according to QM and a 50% chance of behaving exactly according to GR.

Do you know any more about this, about the probability distribution that separates QM from GR?

OK, I want to throw this idea at you. Suppose there exists a new quantum number that only took on values 0 and 1. When it is zero the event behaves according to General Relativity, when it is one the event behaves as if governed by Quantum Mechanics – or vice versa. Like other quantum numbers it takes on its integer values only when observed and between observations exists as a mixture of states – part quantum mechanics and part general relativity. The new quantum number would not be self referential – ie. when in the GR state it would not switch itself off. The mixing of states would be by matrix mechanics, perhaps with a time scale like neutrino state transitions, and perhaps with a momentum-like scale – GR dominates at high momentum.

Would this be a unification of quantum mechanics and general relativity?

mollwollfumble said:

mollwollfumble said:

One of the great unknowns of our age, possibly the greatest, is what determines the boundary between quantum mechanical behavior and classical (GR) behaviour. Chemistry bridges the size scale between the small quantum behaviour and the large classical behaviour. So I’ve been waiting for chemists to announce equations that determine whether a given system will be behave according to QM or GR, the boundary between the two.

It hasn’t happened. In 40 years of looking, I’ve only seen one article, probably in Scientific American, that deals with measuring the interface between QM and GR, and even that didn’t give details. The article was about molecular rotors.

In a molecular rotor, a relatively small part of a larger molecule can rotate into various orientations relative to the rest of the molecule. In classical behaviour, the energy of the system is given by
E=L²/2I
where L is the angular momentum and I is the inertia. In quantum behavior, the energy of the system is given by
E=(h/2π)²;J(J+1)/2I
where J is the rotational quantum number. By observing the energy of the system, chemists have directly probed the boundary between QM and GR.

It turns out that there is no smooth transition between QM and GR behaviour. Instead, the transition is a statistical one. At a given molecular size, the molecular rotor has a 50% chance of behaving exactly according to QM and a 50% chance of behaving exactly according to GR.

Do you know any more about this, about the probability distribution that separates QM from GR?

OK, I want to throw this idea at you. Suppose there exists a new quantum number that only took on values 0 and 1. When it is zero the event behaves according to General Relativity, when it is one the event behaves as if governed by Quantum Mechanics – or vice versa. Like other quantum numbers it takes on its integer values only when observed and between observations exists as a mixture of states – part quantum mechanics and part general relativity. The new quantum number would not be self referential – ie. when in the GR state it would not switch itself off. The mixing of states would be by matrix mechanics, perhaps with a time scale like neutrino state transitions, and perhaps with a momentum-like scale – GR dominates at high momentum.

Would this be a unification of quantum mechanics and general relativity?

> momentum-like scale

Or, better, a force-like scale. Momentum is mass times velocity; force is mass times acceleration, and includes the force of gravity. For molecular rotors the rotational motion of large chemical groups generates the necessary force to allow a probabilistic switch from quantum to classical GR behaviour.