Introduction 11/7/19: My thoughts on Time and Space
Roughly 7 or 8 years ago, I began to explore popular books in cosmology. I read Brian Greene’s new novel the Hidden Reality about the notion of multiverses. Fresh out of high school, I left the book with some serious issues about the significance of our lives, but once I got past it, I was inspired to explore the idea of reality and the cosmos further. I bought a Fabric of the Cosmos and the Elegant Universe by Greene. I never got around to reading either of these (yet!), but I watched the adaptation of the Fabric of the Cosmos on PBS.
The idea of time dilatation fundamentally changed my perception of reality. However, it was how he discussed the idea of the past and future that really resonated with me. The idea, as I understood it, was that the past, present and future all exist simultaneously within the confines of Space-Time, where time is an extra dimension.
Think of it like points on a line. The start and finish of the line both exist in space. If I have my finger on the start and then move it to the end of the line, the start doesn’t cease to exist; every point on the line exists simultaneously. Now replace that line with the timeline of your life. You are at some point between the start and finish, and if time is another dimension like space, the start and finish of that line still exist within the universe. Greene gives a good overview of this idea here, in this clip from the PBS adaption of his novel.
I now understand this idea is called the Block Universe or Eternalism. Essentially, all points in time exist simultaneously. I have been thinking about this more of late, and I have wondered if I misunderstood Greene. Rewatching this video, I see this is exactly what he is saying.
What I want to know is why do we assume a block universe? How much of this idea is based in science vs philosphy/metaphysics? I want to understand what the alternative is and why the block universe is either necessary or at least the best hypothesis? I now appreciate how these types of hypotheses are always incomplete. Does the future exist? If this was true, does this disregard the notion of a big rip or pinch (the end of the universe), or can we think of time like space, stretching outward where the past exists as we exist but the future is in the process of being created? I think the latter is my preferred way of thinking.
Unfortunately, I have not earned that conclusion. That is why I’ve decided to try and pursue this further. In Time Reborn, Smolin presents the common arguments for the past and present existing as Greene suggests, and then he claims to use the scientific method to prove it wrong. His goal: demonstrate the past does not exist and neither does the future. There is only the now.
Now, I am reading this because I want to learn, but it’s also a casual read fueled by my fascination of the subject. This is still for fun, not an academic pursuit. Therefore, this isn’t exactly an analysis of his argument. What I hope to do is discuss my thoughts on his arguments, summarizing where possible. I may get things wrong, but in the end, I hope I still leave with a better idea of the subject matter than when I went in.
Update 11/8/19 (42% progress)
I just reached the second part of this work where he moves from explaining the block universe to try and disprove it. I am loving the conversation. I would attribute that more to my interest in the topic than his writing, but that is fine too. The way he is describing relativity is very reference focused. It seems to be suggesting that just because our perceptions of time are altered that does not mean time itself is. To be clear, he has not explicitly said this. Rather, it is something I am wondering. For example, we can look at star in the sky and recognize the light we see was from years ago; it takes time to reach us. That doesn’t mean at this moment the star isn’t outputting new light. Nor does it mean the past is still there. Rather, the past version of the star has only had a delayed effect.
What I am curious about is whether the perceptions Greene highlights in the video above is a matter of perception or is the causality of the two moments linked. Sure, the past can effect the future, but can that alien in the future effect past versions of earth? If not, is it really right to say the past earth exist in some realm of space time. I suspect I am not seeing the full picture, but it is still important to recognize the limits of what we can know and suspect. If a universe where all versions of time exist is indistinguishable from one where it doesn’t exist, is it worth believing? I think that is essentially Occam’s razor, where the simplest answer is usually the best one.
However, it seems as though Somlin is setting up to make an argument of the laws of the universe evolving rather than staying the same. In which case, we can apply the same logic of the simplest answer being the best one. We have yet to see the laws of the universe change, so is it really appropriate to assume they are? I can’t say for sure if I am interpreting this correctly. Although, I am enjoying it immensely.
I did a bit of digging to find other discussions of Somlin’s argument and came across one scientist’s response which I found worth mentioning.
Smolin’s treatment of this topic is, unfortunately, typical: His book does a poor job of distinguishing established results, speculative ideas, and personal opinions.Steven Carlip, Physics Today 66, 9, 48 (2013); https://doi.org/10.1063/PT.3.2118
I think this highlights the issue at large (and many on the edge of science). We need to recognize the firm from the speculative and everything in between. Carlip is actually hesitant to recommend this to the lay reader because it is difficult to distinguish between speculation and actual results. I am no cosmologist, but hopefully I can at least recognize opinion over fact. The problem is my knowledge of the facts is tenuous. Carlip also recommended another book as a better resource: From Eternity to Here: The Quest for the Ultimate Theory of Time by Sean Carroll. I am more familiar with Carroll. He has a great podcast, Mindscape, that invites experts to discuss topics in science, and I find it really easy to follow and very engaging. I’d also like a take on the conventional way of thinking about the topic as opposed to Smolin’s more controversial view.
It seems Smolin is equating the randomness of quantum mechanics to a possible evolution of the laws of physics. Granted, he doesn’t just say that; he goes in depth to try and demonstrate this. However, it all comes across as stating a bunch of supposed facts then tacking on therefore time exists. It’s probably fair to say that at least part of this is my own inability to understand some of what he is saying. Nevertheless, it still feels like he is reaching into the realm of the unknown to find something to fit to his desired result. He talks about quantum mechanics being inconsistent with relativity, and the difference between relativity of space and time. Unfortunately, it’s hard to connect the dots in any meaningful way.
I am content leaving this book somewhat confused. It is Smolin’s responsibility to adequately translate this to the lay reader. He succeeds in many ways. I think this book has left me with a better sense of the two sides; what he has not done is convince me his radical view is a reasonable one. Science will have unanswered questions. However, that is not justification for a complete overhaul of our perception of reality. Given my lack of expertise, I still want to hear from people more adapt in this field. I mentioned one reviewer earlier, but I have come across one by Sean Carroll as well.
I am not trying to sell Carroll as a better expert than Smolin, but if we are going to discuss such a radical belief we need an unbiased rundown of the problems with the new hypothesis Smolin presents. As Carlip is quoted as saying above, Smolin doesn’t do an sufficient job highlighting where his “facts” being to blur into opinions. He works so hard to prove himself right, but he fails to be critical of his own work.
Extraordinary claims require extraordinary evidence.Carl Sagan, paraphrasing Laplace’s principle
His hypothesis are “consistent” as he describes it. The lack of experimental demonstration that he critiques his opposition to (such as in string theory) is not really mentioned until the very end of the book. Where science meets philosophy is similarly muddled.
Smolin seems quite content to draw sweeping conclusions from essentially philosophical arguments, which is not how science traditionally works. There are no necessary hypotheses; there are only those that work, and those that fail.Sean Carroll, on his blog
While my own understanding of the material is limited, I must follow the consensus of the general scientific community. Of course science can be wrong; that doesn’t mean it isn’t the closest to the truth most of the time. As I said earlier, I think this book has given me a good idea of what that is, but it still leaves me wanting to learn more about the traditional way of thinking. I intend to read Carroll’s book mentioned above on time, but for now I’ll mention the brief overview he gives on his blog.
Carroll suggests Smolin is working on a problem we’ve already solved. He suggests everything we know is consistent with the block/eternalism view of the universe, and it doesn’t put the “now” into a special position as we see in Possibilism. This is a good representation of my understanding of this topic. My confusion comes from Carroll suggesting Smolin is pushing the idea of Possibilism when I took it that he was pushing Presentism. Smolin explicitly says, he is asserting the past and future do not exist, only the now. Now I am wondering if my entire perceived understanding of the book is wrong or if it is Carroll who misrepresented Smolin’s position. That just suggest I need a better explanation on the three realms of thought. Hopefully his book will offer that. I also bought Smolin’s follow up this novel (The Singular Universe and the Reality of Time), but I am not sure if I want to read it anymore.
In any case, it is a fascinating read that, if read, likely will need additional readings. I enjoyed the book, but I left it confused in places and dissatisfied. 3.25/5 stars.