2017-02-16 13:34:49 UTC
"Smolin wishes to hold on to the reality of time. But to do so, he must overcome a major hurdle: General and special relativity seem to imply the opposite. In the classical Newtonian view, physics operated according to the ticking of an invisible universal clock. But Einstein threw out that master clock when, in his theory of special relativity, he argued that no two events are truly simultaneous unless they are causally related. If simultaneity - the notion of "now" - is relative, the universal clock must be a fiction, and time itself a proxy for the movement and change of objects in the universe. Time is literally written out of the equation. Although he has spent much of his career exploring the facets of a "timeless" universe, Smolin has become convinced that this is "deeply wrong," he says. He now believes that time is more than just a useful approximation, that it is as real as our guts tell us it is - more real, in fact, than space itself. The notion of a "real and global time" is the starting hypothesis for Smolin's new work, which he will undertake this year with two graduate students supported by a $47,500 grant from FQXi."
"And by making the clock's tick relative - what happens simultaneously for one observer might seem sequential to another - Einstein's theory of special relativity not only destroyed any notion of absolute time but made time equivalent to a dimension in space: the future is already out there waiting for us; we just can't see it until we get there. This view is a logical and metaphysical dead end, says Smolin."
"Was Einstein wrong? At least in his understanding of time, Smolin argues, the great theorist of relativity was dead wrong. What is worse, by firmly enshrining his error in scientific orthodoxy, Einstein trapped his successors in insoluble dilemmas..."
But Smolin not only rejects Einstein's relative time - he also worships it:
QUESTION: Setting aside any other debates about relativity theory for the moment, why would the speed of light be absolute? No other speeds are absolute, that is, all other speeds do indeed change in relation to the speed of the observer, so it's always seemed a rather strange notion to me.
LEE SMOLIN: Special relativity works extremely well and the postulate of the invariance or universality of the speed of light is extremely well-tested. It might be wrong in the end but it is an extremely good approximation to reality.
QUESTION: So let me pick a bit more on Einstein and ask you this: You write (p. 56) that Einstein showed that simultaneity is relative. But the conclusion of the relativity of simultaneity flows necessarily from Einstein's postulates (that the speed of light is absolute and that the laws of nature are relative). So he didn't really show that simultaneity was relative - he assumed it. What do I have wrong here?
LEE SMOLIN: The relativity of simultaneity is a consequence of the two postulates that Einstein proposed and so it is deduced from the postulates. The postulates and their consequences are then checked experimentally and, so far, they hold remarkably well.
The champion is undoubtedly Steven Jonathan Carlip, professor of physics at the University of California, Davis. Carlip is a practitioner of triple- and even quadruplethink. A synopsis of his teaching: The speed of light is constant by definition. Einstein said the speed of light is variable in a gravitational field - an interpretation which is perfectly valid and makes good physical sense - but after Einstein the speed of light in a gravitational field somehow became constant and is going to remain so forever. So constant that "it does not even make any sense to say that it varies". Finally, the speed of light falling in a gravitational field is twice as variable as the speed of ordinary falling bodies:
Steve Carlip: "Is c, the speed of light in vacuum, constant? At the 1983 Conference Generale des Poids et Mesures, the following SI (Systeme International) definition of the metre was adopted: The metre is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second. This defines the speed of light in vacuum to be exactly 299,792,458 m/s. This provides a very short answer to the question "Is c constant": Yes, c is constant by definition! [...] Einstein went on to discover a more general theory of relativity which explained gravity in terms of curved spacetime, and he talked about the speed of light changing in this new theory. In the 1920 book "Relativity: the special and general theory" he wrote: "...according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity [...] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position." Since Einstein talks of velocity (a vector quantity: speed with direction) rather than speed alone, it is not clear that he meant the speed will change, but the reference to special relativity suggests that he did mean so. This interpretation is perfectly valid and makes good physical sense, but a more modern interpretation is that the speed of light is constant in general relativity. [...] Finally, we come to the conclusion that the speed of light is not only observed to be constant; in the light of well tested theories of physics, it does not even make any sense to say that it varies."
Steve Carlip: "It is well known that the deflection of light is twice that predicted by Newtonian theory; in this sense, at least, light falls with twice the acceleration of ordinary "slow" matter."