# Bohr einstein relationship

### Einstein–Bohr Friendship Recounted by Bohr's Grandson - Scientific American

The Bohr–Einstein debates were a series of public disputes about quantum . father of quantum mechanics, had a notorious love-hate relation with the subject. In , when Albert Einstein began his famous series of battles at the Solvay Conference in Brussels with Danish physicist Niels Bohr over the. The Bohr–Einstein debates were a series of public disputes about quantum mechanics .. At this point, Einstein turns to his celebrated relation between mass and energy of special relativity: E = m c 2 {\displaystyle E=mc^{2}} E=mc^{2 }.

At this point Einstein brings into play the first screen as well and argues as follows: In realistic conditions the mass of the screen is so large that it will remain stationary, but, in principle, it is possible to measure even an infinitesimal recoil.

If we imagine taking the measurement of the impulse of the screen in the direction X after every single particle has passed, we can know, from the fact that the screen will be found recoiled toward the top bottomwhether the particle in question has been deviated toward the bottom or top, and therefore through which slit in S2 the particle has passed. The interference takes place precisely because the state of the system is the superposition of two states whose wave functions are non-zero only near one of the two slits.

On the other hand, if every particle passes through only the slit b or the slit c, then the set of systems is the statistical mixture of the two states, which means that interference is not possible.

If Einstein is correct, then there is a violation of the principle of indeterminacy. Bohr's response[ edit ] Bohr's response was to illustrate Einstein's idea more clearly using the diagram in Figure C. Figure C shows a fixed screen S1 that is bolted down. Then try to imagine one that can slide up or down along a rod instead of a fixed bolt.

Bohr observes that extremely precise knowledge of any potential vertical motion of the screen is an essential presupposition in Einstein's argument. In fact, if its velocity in the direction X before the passage of the particle is not known with a precision substantially greater than that induced by the recoil that is, if it were already moving vertically with an unknown and greater velocity than that which it derives as a consequence of the contact with the particlethen the determination of its motion after the passage of the particle would not give the information we seek.

## Physicist suggests Einstein could have beaten Bohr in famous thought experiment

Before the process even begins, the screen would therefore occupy an indeterminate position at least to a certain extent defined by the formalism. Now consider, for example, the point d in figure A, where the interference is destructive.

Any displacement of the first screen would make the lengths of the two paths, a—b—d and a—c—d, different from those indicated in the figure.

If the difference between the two paths varies by half a wavelength, at point d there will be constructive rather than destructive interference. The ideal experiment must average over all the possible positions of the screen S1, and, for every position, there corresponds, for a certain fixed point F, a different type of interference, from the perfectly destructive to the perfectly constructive.

The effect of this averaging is that the pattern of interference on the screen F will be uniformly grey. Once more, our attempt to evidence the corpuscular aspects in S2 has destroyed the possibility of interference in F, which depends crucially on the wave aspects.

In order to realize Einstein's proposal, it is necessary to replace the first screen in Figure A S1 with a diaphragm that can move vertically, such as this proposed by Bohr. It should be noted that, as Bohr recognized, for the understanding of this phenomenon "it is decisive that, contrary to genuine instruments of measurement, these bodies along with the particles would constitute, in the case under examination, the system to which the quantum-mechanical formalism must apply.

With respect to the precision of the conditions under which one can correctly apply the formalism, it is essential to include the entire experimental apparatus. In fact, the introduction of any new apparatus, such as a mirror, in the path of a particle could introduce new effects of interference which influence essentially the predictions about the results which will be registered at the end.

In particular, it must be very clear that On the other hand, Bohr consistently held that, in order to illustrate the microscopic aspects of reality, it is necessary to set off a process of amplification, which involves macroscopic apparatuses, whose fundamental characteristic is that of obeying classical laws and which can be described in classical terms. This ambiguity would later come back in the form of what is still called today the measurement problem.

### New light shed on old dispute between Einstein and Bohr

In a recent experiment, an apparatus to test this debate was developed and implemented. The test consisted of a free-floating molecular double slit and the momentum change of the atom scattering from it. The results of this experiment were compared to quantum mechanical, and semi-classical models.

The results revealed that the classical description of the slits, used by Einstein, provides a surprisingly good description of the experimental results, even for a microscopic system, if the momentum transfer is not ascribed to a specific pathway but shared coherently and simultaneously between both.

A wave extended longitudinally passes through a slit which remains open only for a brief interval of time. Beyond the slit, there is a spatially limited wave in the direction of propagation. In many textbook examples and popular discussions of quantum mechanics, the principle of indeterminacy is explained by reference to the pair of variables position and velocity or momentum.

It is important to note that the wave nature of physical processes implies that there must exist another relation of indeterminacy: Bohr's thinking is always on the epistemological level, describing not reality but only our information about reality. Rudolf Peierlsinterview in The Ghost in the Atom: Davies and Julian R.

Consolidation and extension of the conception of complementarity". His life and work as seen by his friends and colleagues Albert Einstein, who was in many ways the father of quantum mechanics, had a notorious love-hate relation with the subject. His debates with Niels Bohr—Bohr completely accepting of quantum mechanics and Einstein deeply skeptical— are famous in the history of science.

- New light shed on old dispute between Einstein and Bohr
- Bohr–Einstein debates
- Viewpoint: Closing the Door on Einstein and Bohr’s Quantum Debate

It was generally accepted by most physicists that Bohr won and Einstein lost. Both Bohr and Einstein were subtle men. Einstein tried very hard to show that quantum mechanics was inconsistent; Bohr, however, was always able to counter his arguments.

But in his final attack Einstein pointed to something so deep, so counterintuitive, so troubling, and yet so exciting, that at the beginning of the twenty-first century it has returned to fascinate theoretical physicists. The Theoretical MinimumPreface To this day, many researchers agree with Bohr's pragmatic attitude.

The history books say that Bohr has proved Einstein wrong. But others, including myself, suspect that, in the long run, the Einsteinian view might return: Einstein's original objections could be overturned, but problems still arise if one tries to formulate the quantum mechanics of the entire universe where measurements can never be repeatedand if one tries to reconcile the laws of quantum mechanics with those of gravitation.

### Bohr–Einstein debates - Wikiquote

But I am running far ahead in my story I will return to this point in chapter For a correct description of atoms and molecules, quantum mechanics is a perfect theory. Gerard 't HooftIn search of the ultimate building blocksCh. The magical mystery of the quanta The other mistake that is widely attributed to Einstein is that he was on the wrong side in his famous debate with Niels Bohr over quantum mechanics, starting at the Solvay Congress of and continuing into the s.

Einstein rejected the notion that the laws of physics could deal with probabilities, famously decreeing that God does not play dice with the cosmos. But history gave its verdict against Einstein—quantum mechanics went on from success to success, leaving Einstein on the sidelines. All this familiar story is true, but it leaves out an irony. The Copenhagen interpretation describes what happens when an observer makes a measurement, but the observer and the act of measurement are themselves treated classically.