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Gravity
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If you read and think about the FAQ, then, in philosophy terms, the ontological character of simultaneity in SR subject to interpretation. The philosophic analog of minimalist interpretation is that simultaneity has no reality at all in SR (rather than being something real and frame dependent, it is a frame dependent convention with no reality status). Also, note that block universe and LET would provide radically different 'reality descriptions' of the Andromeda paradox, yet both are indistinguishable by experiment.Gravity said:I was unsure, but thought, due to the argument/paradox being based entirely of special relativity, specifically relativity of simultaneity that it would be allowed...?
Well, a trivial, physics based argument that you can't prove determinism from SR is that QFT is the basis of the best theories we have for matter (the standard model). QFT is based on SR yet is non-deterministic.Gravity said:I was unsure, but thought, due to the argument/paradox being based entirely of special relativity, specifically relativity of simultaneity that it would be allowed. And also that I am not asking for opinion on determinism/free, it seems to be determinism to me, but I can't see it ever called it, so I'm wondering whether I'm missing something...?
PAllen said:Also, note that block universe and LET would provide radically different 'reality descriptions' of the Andromeda paradox, yet both are indistinguishable by experiment.
Gravity said:due to the argument/paradox being based entirely of special relativity, specifically relativity of simultaneity that it would be allowed.
Hahaha, no it's very helpful, thank you.PeterDonis said:To the extent that the argument claims to just be deducing consequences from SR, it is not valid. The key error is in this sentence (from the Penrose quote given in the Wikipedia article):
"Then they can hark back to that chance encounter, and come to the conclusion that at that time, according to one of them, the decision lay in the uncertain future, while to the other, it lay in the certain past."
SR, as a theory, does not support the claim that "according to one of them, the decision lay in the uncertain future, while to the other, it lay in the certain past". That is because, in SR, the "certain past" of a given observer at a given event does not include all of spacetime to the past of that observer's surface of simultaneity through that event; it only includes the past light cone of that event. Similarly, the "uncertain future" of a given observer at a given event does not include all of spacetime to the future of that observer's surface of simultaneity through that event; it only includes the future light cone of that event. There is a third region of spacetime, the spacelike separated region, which falls into neither of these categories in SR.
This is one of the fundamental differences between SR and Newtonian physics; in Newtonian physics, the third region does not exist. And Penrose, in the passage quoted, is erroneously making use of Newtonian intuitions when he uses the terms "uncertain future" and "certain past" to refer to an event that is spacelike separated from the observer. What makes this really surprising is that, in an earlier section of the same book, Penrose actually explains, in detail, the distinction I have just described--he explicitly talks about the third region of spacetime, how it's there in SR and isn't in Newtonian physics, and even gives it a name, "Elsewhere". Then, in the passage quoted, he forgets all of that and goes back to Newtonian assumptions. It's one of the best simple illustrations I've seen of why you can't trust authority; even world-class experts in a field can make simple-minded errors.
Okay, I'll stop ranting now. ;)
PeterDonis said:It's one of the best simple illustrations I've seen of why you can't trust authority; even world-class experts in a field can make simple-minded errors.
PhoebeLasa said:I certainly wouldn't so quickly dismiss the writings of anyone with Penrose's reputation and credentials.
Penrose's Andromeda paradox is a thought experiment proposed by Sir Roger Penrose to challenge the notion of determinism in the universe. It involves imagining a spaceship flying towards the Andromeda galaxy at a constant speed. According to determinism, the future state of the universe should be predictable based on the current state. However, due to the expanding nature of the universe, the Andromeda galaxy will eventually move out of the observable universe, making it impossible to predict the future trajectory of the spaceship.
Penrose's Andromeda paradox challenges determinism by highlighting the limitations of predicting the future state of the universe. It suggests that there are certain events, like the movement of galaxies, that are beyond our control and cannot be predicted based on the current state of the universe. This challenges the idea that everything in the universe is predetermined and raises questions about the concept of free will.
No, Penrose's Andromeda paradox does not disprove determinism. It simply raises questions and challenges the concept of determinism by showing its limitations. Determinism is still a widely accepted concept in science and philosophy, and there is no conclusive evidence to disprove it.
As a thought experiment, Penrose's Andromeda paradox cannot be tested in a physical sense. However, it can be further explored and debated through theoretical and philosophical discussions. Some scientists have proposed alternate theories, such as the multiverse theory, to explain the paradox.
The implications of Penrose's Andromeda paradox are still a subject of debate and speculation. It challenges our understanding of the universe and raises questions about the concept of free will and the limitations of determinism. It also highlights the need for further research and exploration in the field of cosmology and theoretical physics.