No, the delayed choice quantum eraser experiment does not deny the existence of the past. It is an experiment that explores the counterintuitive behavior of quantum particles and the role of measurement and observation in quantum mechanics.
The delayed choice quantum eraser experiment involves the use of entangled photons and a setup that allows for interference patterns to be observed. In the experiment, the behavior of a photon is observed to determine which path it takes (particle-like behavior) or to preserve its wave-like behavior. The interesting aspect is that this observation can be performed either before or after the photon has interacted with another particle.
The experiment does challenge our classical intuitions about causality and the notion of a definite past. It shows that the choice of whether to observe or erase the information about the path of the photon can retroactively affect the interference pattern observed in the past. However, this does not mean that the past itself is negated or does not exist.
The delayed choice quantum eraser experiment raises profound questions about the nature of reality, the role of measurement, and the interpretation of quantum mechanics. It suggests that the behavior of quantum systems is not fully determined by their past history but can be influenced by the choices made in the present or future. Nonetheless, it does not imply that the past itself is somehow unreal or non-existent.
It's important to note that various interpretations of quantum mechanics exist, and the delayed choice quantum eraser experiment is subject to different interpretations and debates among physicists. Different interpretations offer different explanations for the observed phenomena, but none of them fundamentally deny the existence of the past.