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arXiv:2501.17407 · Journal of Physics Conference Series

Time dispersion in bound states

John Ashmead

Published Apr 1, 2025• 0 citations
arXivHTMLPDF

Abstract

Abstract In quantum mechanics time is generally treated as a parameter rather than an observable. For instance wave functions are treated as extending in space, but not in time. But from relativity we expect time and space should be treated on the same basis. What are the effects if time is an observable? Are these effects observable with current technology? In earlier work we showed we should see effects in various high energy scattering processes. We here extend that work to include bound states. The critical advantage of working with bound states is that the predictions are significantly more definite, taking the predictions from testable to falsifiable. We estimate the time dispersion for hydrogen as .177 attoseconds, possibly below the current threshold for detection. But the time dispersion should scale as the 3/2 power of the principle quantum number n. Rydberg atoms can have n of order 100, implying a boost by a factor of 1000. This takes the the time dispersion to 177 attoseconds, well within reach of current technology. There are a wide variety of experimental targets: any time-dependent processes should show effects. Falsification will be technically challenging (due to the short time scales) but immediate and unambiguous. Confirmation would have significant implications for attosecond physics, quantum computing and communications, quantum gravity, and the measurement problem. And would suggest practical uses in these areas as well as circuit design, high speed biochemistry, cryptography, fusion research, and any area involving change at attosecond time scales.

DOI
10.1088/1742-6596/2987/1/012011

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Abstract In quantum mechanics time is generally treated as a parameter rather than an observable. For instance wave functions are treated as extending in space, but not in time. But from relativity we expect time and space should be treated on the same basis. What are the effects if time is an observable? Are these effects observable with current technology? In earlier work we showed we should see effects in various high energy scattering processes. We here extend that work to include bound states. The critical advantage of working with bound states is that the predictions are significantly more definite, taking the predictions from testable to falsifiable. We estimate the time dispersion for hydrogen as .177 attoseconds, possibly below the current threshold for detection. But the time dispersion should scale as the 3/2 power of the principle quantum number n. Rydberg atoms can have n of order 100, implying a boost by a factor of 1000. This takes the the time dispersion to 177 attoseconds, well within reach of current technology. There are a wide variety of experimental targets: any time-dependent processes should show effects. Falsification will be technically challenging (due to the short time scales) but immediate and unambiguous. Confirmation would have significant implications for attosecond physics, quantum computing and communications, quantum gravity, and the measurement problem. And would suggest practical uses in these areas as well as circuit design, high speed biochemistry, cryptography, fusion research, and any area involving change at attosecond time scales.
In quantum mechanics the time dimension is treated as a parameter, while the three space dimensions are treated as observables. This assumption is both untested and inconsistent with relativity. From dimensional analysis, we expect quantum effects along the time axis to be of order an attosecond. Such effects are not ruled out by current experiments. But they are large enough to be detected with current technology, if sufficiently specific predictions can be made. To supply such we use path integrals. The only change required is to generalize the usual three dimensional paths to four. We predict a large variety of testable effects. The principal effects are additional dispersion in time and full equivalence of the time/energy uncertainty principle to the space/momentum one. Additional effects include interference, diffraction, and entanglement in time. The usual ultraviolet divergences do not appear: they are suppressed by a combination of dispersion in time and entanglement in time. The approach here has no free parameters; it is therefore falsifiable. As it treats time and space with complete symmetry and does not suffer from the ultraviolet divergences, it may provide a useful starting point for attacks on quantum gravity.
Abstract If we use the path integral approach, we can write quantum electrodynamics (QED) in a way that is manifestly relativistic. However the path integrals are confined to paths that are on mass-shell. What happens if we extend QED by computing the path integrals over all paths in energy momentum space, not only those on mass-shell? We use the requirement of covariance to do this in an unambiguous way. This gives a QED where the time/energy components appear in a way that is manifestly parallel to the space/momentum components: we have dispersion in time, entanglement in time, full equivalence of the Heisenberg uncertainty principle (HUP) in time to the HUP in space, and so on. Entanglement in time has the welcome side effect of eliminating the ultraviolet divergences. We recover standard QED in the long time limit. We predict effects at scales of attoseconds. With recent developments in attosecond physics and in quantum computing, these effects should be detectable. Since the predictions are unambiguous and testable the approach is falsifiable. Falsification would sharpen our understanding of the role of time in QED. Confirmation would have significant implications for attosecond physics, quantum computing and communications, and quantum gravity.
Abstract Does the Heisenberg uncertainty principle (HUP) apply along the time dimension in the same way it applies along the three space dimensions? Relativity says it should; current practice says no. With recent advances in measurement at the attosecond scale it is now possible to decide this question experimentally. The most direct test is to measure the time-of-arrival of a quantum particle: if the HUP applies in time, then the dispersion in the time-of-arrival will be measurably increased. We develop an appropriate metric of time-of-arrival in the standard case; extend this to include the case where there is uncertainty in time; then compare. There is – as expected – increased uncertainty in the time-of-arrival if the HUP applies along the time axis. The results are fully constrained by Lorentz covariance, therefore uniquely defined, therefore falsifiable. So we have an experimental question on our hands. Any definite resolution would have significant implications with respect to the role of time in quantum mechanics and relativity. A positive result would also have significant practical applications in the areas of quantum communication, attosecond physics (e.g. protein folding), and quantum computing.
The concept of position and its measurement are fundamental to modern navigation technology as well as to theoretical physics. Nevertheless, a consistent notion of position has not been found in modern physics because of apparent inconsistencies between quantum mechanics and relativity. In quantum mechanics the probability distribution for a particle's position is determined by its wave function. A wave function strictly localized in space describes a particle within that locality, and nowhere else. But the quantum equations of motion predict the function will disperse, after any length of time at all, to occupy all space. Therefore the theoretical prediction is that, shortly after detection in a laboratory, a particle may be found anywhere in the universe, including regions requiring faster-than-light travel to reach. This contradicts the theory of relativity, which precludes a body traveling faster than the speed of light. The conflict arises from unexamined assumptions regarding the time of the measurement event and the time of the system under measurement. The prevailing view in physics is that time is only a parameter, having a definite value, describing dynamic changes in physical systems. This view endures even though quantum mechanics recognizes position as a quantum variable with inherent uncertainty, and relativity indicates that time should be placed on the same footing as position. But if time is recognized as a quantum variable with inherent uncertainty, the conceptual problems with position are resolved. The particle has finite probability of being in the past (or future) of the observer, while the quantum mechanical operator describing the position measurement contains a term which extrapolates from the intrinsic time of the particle to the time of the observer. Being potentially well in the past of the measurement event, the particle has time to travel to remote regions without exceeding the speed of light, and the conflict with relativity is resolved. A relativistic quantum theory can therefore be constructed incorporating a well-defined concept of position.
Our formalism for describing quantum measurements is generalized to the multitime case and used to derive rigorous time-energy uncertainty relations. For a free particle, we find that $T\ensuremath{\delta}H\ensuremath{\ge}\frac{1}{2}$, where $\ensuremath{\delta}H$ is the dispersion in energy and TTT is the measurement duration as given by an external clock of arbitrarily high accuracy. Moreover, any system used as a clock obeys $\ensuremath{\delta}t\ensuremath{\delta}H\ensuremath{\ge}\frac{1}{2}$, where $\ensuremath{\delta}t$ is the dispersion in the values of time as measured by the system.