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Really? There is no objective reality out there. It makes no sense to talk about reality independent of the physical model. Classical science is based on the be

Really? There is no objective reality out there. It makes no sense to talk about reality independent of the physical model. Classical science is based on the belief that there exists a real external world whose properties are definite and independent of the observer who perceives them. According to classical science, certain objects exist and have physical properties, such as speed and mass, that have well-defined values. In this view our theories are attempts to describe those objects and their properties, and our measurements and perceptions correspond to them. Both observer and observed are parts of a world that has an objective existence, and any distinction between them has no meaningful significance. In other words, if you see a herd of zebras fighting for a spot in the parking garage, it is because there really is a herd of zebras fighting for a spot in the parking garage. All other observers who look will measure the same properties, and the herd will have those properties whether anyone observes them or not. In philosophy that belief is called realism. Though realism may be a tempting viewpoint what we know about modern physics makes it a difficult one to defend. For example, according to the principles of quantum physics a particle has neither a definite position nor a definite velocity unless and until those quantities are measured by an observer. It is therefore not correct to say that a measurement gives a certain result because the quantity being measured had that value at the time of the measurement. In fact, in some cases individual objects don’t even have an independent existence but rather exist only as part of an ensemble of many.

chestervonwinch 11y ago
Interesting. I don't know quantum theory, but let me ask: A weighted coin flipping in the air is neither heads nor tails until observed. That we can't observe the property of the coin (its weighted bias) while it's in the air flipping, doesn't change the coin's properties. In fact, we wouldn't be able to measure the bias from a single observation. Yet, if I constructed the coin to be precisely heavier on heads versus tails according to some ratio, it would have that property the whole time, no?
- super_mario 11y ago
  That contrived example doesn't work because head or tail experiment outcome is defined as coin landing with that side up. While the coin hasn't yet landed, it makes no sense to speak of "landed head facing up = heads" or "landed tail facing up = tails". The space of events in this case are outcomes of coin tosses. We don't care about what happens while the coin is in the air. To determine if the coin is biased you would need to repeat the experiment large number of times and see if you get experimental outcomes that do not agree with the expected values given by law of large numbers. This is not how things are in quantum mechanics though. Uncertainty principle is an intrinsic property of quantum systems. It's not the case that the act of measuring somehow disturbs the system and changes the measured values. It's that values are undetermined at all until they are measured. And even then there is inverse relationship between how precisely you can know momentum of the particle vs its position. The more you know one the less you can know the other.

chestervonwinch 11y ago

Interesting. I don't know quantum theory, but let me ask: A weighted coin flipping in the air is neither heads nor tails until observed. That we can't observe the property of the coin (its weighted bias) while it's in the air flipping, doesn't change the coin's properties. In fact, we wouldn't be able to measure the bias from a single observation. Yet, if I constructed the coin to be precisely heavier on heads versus tails according to some ratio, it would have that property the whole time, no?

super_mario 11y ago
That contrived example doesn't work because head or tail experiment outcome is defined as coin landing with that side up. While the coin hasn't yet landed, it makes no sense to speak of "landed head facing up = heads" or "landed tail facing up = tails". The space of events in this case are outcomes of coin tosses. We don't care about what happens while the coin is in the air. To determine if the coin is biased you would need to repeat the experiment large number of times and see if you get experimental outcomes that do not agree with the expected values given by law of large numbers. This is not how things are in quantum mechanics though. Uncertainty principle is an intrinsic property of quantum systems. It's not the case that the act of measuring somehow disturbs the system and changes the measured values. It's that values are undetermined at all until they are measured. And even then there is inverse relationship between how precisely you can know momentum of the particle vs its position. The more you know one the less you can know the other.