Portals to a New Reality Quotes

“On top of that, we have also seen that in quantum mechanics, different observers could see different factual states of affairs. In one branch, Bob sees a dead cat, while in another, a different copy of him sees a live cat. And from the outside, Alice still thinks of the two as being in a superposition, so both outcomes are true at the same time. In that sense, quantum mechanics also allows for the existence of multiple times, since each copy of Bob could have a clock that showed a unique time in each branch, and both these times could be different from that of Alice’s clock.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“There is much to be skeptical about when it comes to Dunne’s logic, entertaining though it is. However, we have already seen that, in relativity, objects traveling at different speeds measure different amounts of time. In this sense, relativity already contains infinitely many possible rates at which time could flow!”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“The ideas explored in this chapter are intimately connected with the observation that different times are just like different realities in space. And the key principle behind this is the coherent control of quantum information. Any two distinguishable states of affairs can always be put into a quantum superposition.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“This is why Dirac said, in his usual dry manner: “Bohr’s doctrine may be useful for students preparing examinations, but not for physicists doing physics.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“Copenhagen logic implies that a quantum system can only consistently stay fully quantum if it never couples to any classical systems.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“Incidentally, conservation of information also contradicts the Copenhagen interpretation of quantum physics (as well as various collapse modifications in which quantum physics, under some conditions, is forced to become classical).”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“In that sense, information joins energy as a quantity in physics that cannot be altered in any interaction. This is true only in totality, and information can of course be gained by a measurement in a relative way.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“The fourth and final principle we need is that information is always conserved. It cannot be erased and it cannot be created.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“The surprising thing is that, despite entanglement, the same is true in quantum physics: we can infer the state of a quantum system composed of many subsystems by locally measuring each subsystem and then gathering all the data together. The principle of local tomography says that it suffices to measure the particles separately to understand their joint state of affairs. All the experiments regarding the violation of Bell inequalities that have been performed so far, including the three that resulted in a Nobel Prize in 2022, have been performed effectively using local tomography.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“The third important aspect is that information, whether classical or quantum, obeys the principle of local tomography.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“I am convinced that not being aware of the fact that we can superpose any two processes is at the root of why some people think that there is still the measurement problem in quantum mechanics.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“The second key aspect of quantum information is what might be called coherently controlled information processing. Namely, if we have one way of doing something, and another way of doing the same thing, then, by using a single qubit, we can make a superposition of the two processes (by definition, qubits have two distinguishable states that can be superposed).”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“when you bring together systems that are individually described by q-numbers, the combined system is an information medium! In other words, combining two things that can be copied does not always result in a new thing that can be copied. This is the information-theoretic way of understanding the uncertainty principle of quantum mechanics: you can measure a system’s position (something that can be copied) or its velocity (another thing that can be copied), but you can’t measure them both simultaneously to arbitrary accuracy (the things that can be copied individually cannot be copied together). The information-theoretic view is also the best way of understanding quantum measurement. Because we can copy the position of a particle into another particle, but we cannot at the same time copy information about its velocity, the position and velocity states are not fully distinguishable. Each (the position and the velocity) is an information medium in its own right, but when taken together they become superinformation. The totality of q-numbers is superinformation.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“when you bring together systems that are individually described by q-numbers, the combined system is an information medium! In other words, combining two things that can be copied does not always result in a new thing that can be copied. This is the information-theoretic way of understanding the uncertainty principle of quantum mechanics: you can measure a system’s position (something that can be copied) or its velocity (another thing that can be copied), but you can’t measure them both simultaneously to arbitrary accuracy (the things that can be copied individually cannot be copied together).”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“In quantum physics, the uncertainty principle tells us that we can copy the position or we can copy the velocity, but we cannot copy both. This is just another way of saying that the elements of reality in quantum physics are q-numbers. My colleagues Chiara Marletto and David Deutsch call quantum systems “superinformation media.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“Within a physical theory, which elements of reality are capable of carrying information? We can say that something has information if the states encoding this information can be copied—faithfully, without errors—into something else. In quantum physics, things we call observables, otherwise known as our friends the q-numbers, have this property. Different values of a given observable are fully distinguishable from one another, and this is what makes them able to be copied. As I mentioned, each observable is represented by a q-number, and these q-numbers can be copied from one quantum system to another. A perfect example of copying is the quantum measurement we discussed above: it is simply the copying of the information within one q-number of the system into another q-number belonging to the measurer.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“By a funny coincidence, as I was completing this chapter, I came across a beautiful little book in my local secondhand bookstore. It was written by Charles Darwin in 1931. You read that right—and, no, I haven’t made a chronological typo. This is not the Charles Darwin of evolutionary fame but his grandson, who himself was a distinguished physicist. The book, titled The New Conceptions of Matter, is by far the clearest popular exposition of quantum physics I have ever read. The book presents a fantastic account of the view that all matter is made up of waves. It seems amazing to me that at the time Darwin wrote it, quantum physics was only five years old. During that short period, Darwin not only absorbed all the new, revolutionary ideas of quantum physics but also made novel contributions to it and gave us the germ of what I believe to be the best interpretation of quantum physics ever.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“For the quantum electromagnetic field, the electric field and the magnetic field cannot be measured or specified simultaneously, just as the position and momentum of a particle cannot be measured simultaneously in standard quantum mechanics. One of the counterintuitive consequences of the fact that the fundamental entities in the universe are quantum fields (which are really just our old friend, q-waves) is that particles should not be thought of as being elements of reality. In the same way that the position and momentum, as c-numbers, cannot be elements of reality in quantum physics, the same goes for the number of particles that constitute a given system. In other words, the number of particles itself ought to be a q-number, rather than some definite, single-valued number.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“All interactions in quantum physics are described this way. There are particles (pendulums) that interact with other particles (other pendulums) through mediators (which—surprise, surprise—are chains of yet more pendulums). In classical field theory, the electric field values and the magnetic field values are defined at each point in space by three electric field numbers and three magnetic field numbers, all of which change in time. That is the electromagnetic field. When this is quantized, the electric field and the magnetic field become “operators” that generate q-numbers. And it is these operators that exist at every point in space and change with time. That is the quantum electromagnetic field.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“This simple concept forms the basis of quantum field theory. Quantum field theory is all about harmonic oscillators like the grandfather clocks, only quantum! The universe is made up of a stupendously large number of quantum harmonic oscillators, each representing a degree of freedom of the respective underlying field (the electromagnetic field, the electron field, and so on).”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“The fact that quantum physics is Bell non-local and general relativity is not poses no obstacle to their unification.3 When the fundamental entities in general relativity are quantized, the resulting theory of quantum gravity also becomes Bell non-local. Any classical theory that is quantized is automatically—by its very construction—Bell non-local. Failing to appreciate this has been the source of much trouble in the foundations of quantum mechanics. We will discuss this at length when we talk about how to test the quantum nature of the gravitational field.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“Exactly the same is true for quantum fields, the only difference being that what does the waving in the quantum case are the q-numbers pertaining to the field.2 Here the speed of propagation is of course the speed of light. But the speed itself is irrelevant for the concept of locality. Instead, we simply need to require that acting on one subsystem (whatever this is, be it an atom, a photon, or a region of space) cannot instantaneously affect another subsystem. We will spell out below exactly what this means, but suffice it to say that this principle of Einstein’s locality is also true in non-relativistic quantum mechanics. If we have two qubits—and remember, a qubit is the quantum analogue of a bit, and so it is the fundamental unit of quantum information and quantum computation—located at two different places, then acting on one of them cannot change any property (any q-number) of the other qubit. Nevertheless, it is sometimes mistakenly said that quantum physics violates Einstein’s locality. Quantum physics violates an altogether different idea of locality, called Bell locality. In Bell locality, things are described by c-numbers (not q-numbers) locally. And, of course, we know that the violation of Bell’s inequality is in direct conflict with the existence of the c-number-based local reality.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“been tested, and they reach a larger number, 2 × √2. What is the conclusion of all this? It is that we have to give up either of the two assumptions leading to Bell’s inequality. Either each local system in the experiment cannot be independently described by c-numbers, or there is something traveling faster than the speed of light telling one system how to adjust to the measurements performed on the other, faraway system. The latter basically means that relativity goes out the window. So either c-number reality or relativity (or both?) has to be abandoned. My hunch, and the hunch of most other physicists, is that it’s not relativity that fails. So the only conclusion left is that the underlying elements of reality cannot be c-numbers. Rather, they have to be q-numbers. That’s the only reasonable way to explain the violation of Bell’s inequality and not end up violating relativity. And this is very important, as it instructs us how to proceed to test for new physics.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“one. Together, we have (1 × 1) + (−1 × −1) = 2. The Nobel Prize in physics in 2022 was given to three physicists, Alain Aspect, John Clauser, and Anton Zeilinger, “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science.” But it is not just photons that have violated Bell’s inequality and therefore proved EPR wrong and quantum physics right. We have violated it with atoms, subatomic particles, molecules, and so on. More or less anything that we physicists have been able to entangle can be shown to violate Bell’s inequality. These various quantum entangled particles have been tested, and they reach a larger number, 2 × √2.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“we ourselves are also a collection of q-waves. Our q-waves correlate with the q-waves of the alpha particle, and these correlations between q-waves are what quantum entanglement is. And when entanglement happens, c-numbers emerge. The classical world owes its existence to quantum entanglement.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“According to quantum physics, everything is actually made up of waves. But these are q-waves, meaning that the entities that are doing the waving are q-numbers.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“when Heisenberg purged classical physics of the entities he thought were not observable, the most striking consequence was that the position and velocity no longer commute (to say that something does not commute is a mathematical way of telling us that the order in which we multiply them matters). This was the first glimpse of the Heisenberg uncertainty principle. Heisenberg’s second great insight was that he didn’t need to jettison classical physics entirely; all he had to do was change the c-numbers to q-numbers.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“much of the field is still stuck on discussing the very same issues that were raised at the Solvay conference in 1927, ignoring the progress that has since been made. In sharp contrast with these views, here I want to make the point that if we instead embrace quantum theory as a universal theory and all of its consequences, not only is the measurement problem dead and buried, but we can also clearly see a path toward discovering new physics. This will take us to our portals, and it all starts by understanding how observation is completely compatible with quantum physics.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“The amazing fact about this is that we can and are about to test whether (some of) gravity’s components need to be described by q-numbers with current technology.6 The power of such a result is enormous—it would make a huge impact on physics. And it’s all thanks to quantum information and entanglement.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics

“I will here describe an experiment, accessible with current technology, to show that both cannot be right at the same time. The experiment illustrates how we are very much in the same position as Einstein was with Newton and Maxwell when he had to decide whom to side with. The only difference now is that we have to decide whether to side with Heisenberg or Einstein. And it is here that our philosophical interpretations of physics, and the principles of quantum information, will help us decide.”
― Vlatko Vedral Ph. D., Portals to a New Reality: Five Pathways to the Future of Physics