Here are the statements that I will be reacting to from the book “The Grand Design” by Stephen Hawking:
“Quantum physics tells us that no matter how thorough our observation of the present, the (unobserved) past, like the future, is indefinite and exists only as a spectrum of possibilities. The universe, according to quantum physics, has no single past, or history.”
“The fact that the past takes no definite form means that observations you make on a system in the present affect its past.”
“That is underlined rather dramatically by a type of experiment thought up by physicist John Wheeler, called a delayed-choice experiment. Schematically, a delayed-choice experiment is like the double-slit experiment we just described, in which you have the option of observing the path that the particle takes, except in the delayed-choice experiment you postpone your decision about whether or not to observe the path until just before the particle hits the detection screen.”
“Wheeler even considered a cosmic version of the experiment, in which the particles involved are photons emitted by powerful quasars billions of light-years away. Such light could be split into two paths and refocused toward earth by the gravitational lensing of an intervening galaxy. Though the experiment is beyond the reach of current technology, if we could collect enough photons from this light, they ought to form an interference pattern. Yet if we place a device to measure which-path information shortly before detection, that pattern should disappear. ”
“The choice whether to take one or both paths in this case would have been made billions of years ago, before the earth or perhaps even our sun was formed, and yet with our observation in the laboratory we will be affecting that choice.”
“We will see that, like a particle, the universe doesn’t have just a single history, but every possible history, each with its own probability; and our observations of its current state affect its past and determine the different histories of the universe, just as the observations of the particles in the double-slit experiment affect the particles’ past.” (all page 82-83, “The Grand Design”).
My Response:
First of all, as far as the quotes “quantum physics tells us that …the (unobserved) past, like the future, is indefinite and exists only as a spectrum of possibilities.” and “The universe, according to quantum physics, [having] no single past, or history,” it seems to me (and others) that moving from the very small to the very big like this is a massive stretch. There are interpretations of what’s going on at the quantum level that are more rational than this one; the Penrose interpretation for example: https://en.m.wikipedia.org/wiki/Penrose_interpretation, which can be summed up as a particle’s wave function collapsing being caused by its own gravity, with all other ‘probability’ being lost in the collapse. It seems to me that quantum mechanics is a system that generates stability from instability at the very small size level. Thats what it DOES. Larger levels behave differently; while they are half ordered and half chaotic like the science of complexity describes, they do not display the FUNDAMENTAL instability that quantum systems do. Your cat is not a probability wave in a zillion places, he is in one place! There is absolutely no reason why the two size levels should be conflated in the manner that the many worlds hypothesis describes. Also, Einstein believed that the universe is a four dimensional object. If the universe is a four dimensional object, this idea that the past is indefinite can’t be true, because the past, present and future of this (definite) object would be simultaneous.
So, regarding the statement: “The fact that the past takes no definite form means that observations you make on a system in the present affect its past,” I want to point out that the past does not have to be indefinite for observations in the present to affect the past. In a four dimensional universe where the past, present and future are simultaneous, observations in the present would also affect the past, because the two are simultaneous. So, “[Regarding Wheeler’s experiment] The choice whether to take one or both paths in this case would have been made billions of years ago, before the earth or perhaps even our sun was formed, and yet with our observation in the laboratory we will be affecting that choice.” The past, present and future are simultaneous not indefinite relative to the present, as previously discussed, so for me this thought experiment only proves that the universe is a four dimensional object with a definite past, present and future.
My main problem with an indefinite past is that as a philosopher meaning is very important to me, and if the past is indefinite, all meaning is lost. This is because meaning is connected to our simultaneous past, present and future, and eternity. Not only is our universe a simultaneous interactive event (object), but it is an eternal simultaneous interactive event. Meaningful actions hang in eternity and are like beacons for us, showing us behavior to aspire to, and making us proud to be human. In fact, I think that the real purpose of this whole universal system is to preserve meaning and ultimately to become completely conscious.
So, moving on, responding to the quote: “We will see that, like a particle, the universe doesn’t have just a single history, but every possible history, each with its own probability” I have to say that this “many worlds hypothesis” or many histories hypothesis that this statement is referring to involves ridiculous complexity. Frankly I find it messy and ugly. The universe is much more beautiful and coherently designed than that! People will say that this is merely an aesthetic argument, but aesthetic arguments hold more weight than people think when you look at the beauty of the total system. One of the most beautiful aspects of our universal energy system is that it is becoming more conscious and also preserving meaning forever.
David M. Petersen
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