Scientists observe Einstein's gravity in the quantum world

Their point is measuring gravity's influence on a single particle is not necessarily evidence of the existence of the graviton.

Actually, we do need evidence for premises which are not definitions or basic assumptions (axioms). Graviton is still a hypothetical particle and falls under neither of two categories - Definitions or axioms.

This is a global issue with modern particle physics - scientists imagine something and then blink, and two decades and a hundred of books had been published while that something is still not present in any test. It would be fine if that happened rarely, but it seems that it's just par for course nowadays.

Your house has walls to attenuate photons.

Casimir plates are a good example, although Faraday cages are probably better known along with Mu-metal.

So Schrödinger’s cat has an orthogonal state!

(not inside the box)

How could you measure that the cat was inside the room?

The world is made of two types of particle - fermions and bosons. A difference between them is that fermions can not occupy the same quantum state (the Pauli exclusion principle) while bosons can exist as superpositions. Matter is made of electrons, protons and neutrons which are fermions, while the forces are photons, gluons, W , Z and Higgs which are bosons.

In a black hole though … who knows

There is a difference between "being in a superposition" and "occupying the same space". The uncertainty principle basically tells you that an electron is never in a defined place - it exists with some probability in many different places (technically it could be at a definite position, but only if it had completely indefinite momentum, and that's not physically meaningful given energy constraints).

Now, say we have an experiment where two different sources each fire one electron in some direction; and say the electrons have the same spin and other properties except for their initial position and momentum. We can meaningfully say that for a certain location between the two sources there is some > 0 probability for either electron to be there, so the amplitude of each electron's wavefunction at that position is > 0. However, that doesn't mean we can ever find both electrons at that same postion at the same time: the individual wavefunctions are just parts of the two-electron system's wavefunction, and, per the Pauli exclusion principle, that one will be 0 for any state of the form "electron A at position x and electron B at position x". So, for any position, you can find either electron there, but never both.

An additional wrinkle is that this only applies for two identical electrons. If the electrons have different spins, then they can actually be found at the same location at the same time. You can have a spin-up and a spin-down electron in the same place at the same time, but not two spin-up electrons. This is the fundamental property of fermions. However, you can have any number of identical photons at the same location - that's the fundamental property of bosons.

>quantum consciousness or other nonsense

Can you tell me why it is non-sense?

We, through our senses perceive a world. This world we try to understand using physics. But these perceptions itself stands on top of consciousness. So consciousness is at least, as real as the world that physics conventionally tries to reason about. It could be even more fundamental, because you can have only consciousness in this universe, but still could sense a whole universe with "things" inside it. But without consciousness, and just a universe with "things", there is no "sensing"...

Point is, physics should include study of consciousness...

Have you actually hear him talk about it? It is very far from rambling and he will be the first to tell you that he is not sure he is right.

We need physicists to come up with and develop novel ideas to consider no matter how many of them might be entirely wrong.

You know, I pooh poohed his theories. Still do in sum. But there’s a there there that’s building.

Damn Deepak Chopra and his ilk of idiots for making any conversation of quantum mechanics and biology tinged with pseudoscience. Hopefully we’ll keep getting experimental evidence as we go that it’s not at all absurd to consider quantum effects in biology.

That said, those effects are going to look nothing like sustained coherence for long periods of time.

My understanding is that 1) SR doesn't consider acceleration (it's an extension of Galilean/uniform motion), and that 2) when Einstein considered acceleration as well as gravity via the equivalence principle which lead to GR [1]. The key insight of the equivalence principle was that the force from gravity (e.g. standing on the Earth) is no different to the observer in their frame of reference to them being in a room in a rocket accelerating at the same rate as gravity [1], [2].

Thus, if you extend QED/QCD/SM in a similar way (thinking of QED/QCD/SM extensions in terms of acceleration and curved space with the equivalence principle in mind) that may lead to a quantized theory of gravity. -- Sir Roger Penrose has a similar idea/thinking [3].

One of the key challenges with quantizing gravity is in how the terms in the expressions resulting from analyzing the Feynman diagram interactions behave [4] which prevent them being renormalized. For electromagnetism you can formulate the terms using the fine structure constant (via the coulomb potential, ħ, and c) which results in successive terms decreasing in value and thus stabilizing to a single value.

For gravity using Newton's relationship between two masses in a similar way to deriving the fine structure constant you get Gm^2/ħc. Applying E=mc^2 gives GE^2/ħc^5. Using the Planck energy constant gives (E/E_p)^2 for the energy coupling strength. This means that unlike electromagnetism, the successive terms in the Feynman diagram analysis grows exponentially instead of decreasing to 0. Thus, this approach to quantization doesn't work for gravity.

Note: you can still use this to analyze quantum gravitational effects at small energies by evaluating to a given number of terms.

[1] https://www.britannica.com/story/how-albert-einstein-develop...

[2] https://www.ebsco.com/research-starters/physics/equivalence-...

[3] https://www.youtube.com/watch?v=VQM0OtxvZ-Y "We need to 'gravitise' quantum mechanics, not quantise gravity | Roger Penrose | Full interview"

[4] https://www.youtube.com/watch?v=yTEPm5d6mrI "Why Quantum Gravity Doesn't Work"

Can one really derive classical GR completely from a QFT of a spin-2 field? Or only a linear approximation?

As opposed to current models, where one event does not affect subsequent events?

How do you synchronize the clocks and compute the measurement, without depending on the conclusion?

You run into a similar problem with Michelson-Morley: because the apparatus and the light both get distorted by any motion, you can’t even in principle detect the aether wind with interferometry. You need a non-comoving dynamic source, eg, LIGO with black hole collisions.

Their one-way experiments seem to require similar, ie, we can observe dynamics but cannot measure a static bias.