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Presentism and Special Relativity
Are Presentism and Special Relativity incompatible?
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jedaisoul
exponent of reason  Usergroup: Members Joined: Aug 14, 2008 Location: UK Total Topics: 13 Total Posts: 700 |
 #1
Subject: Presentism and Special Relativity It is said that presentism is incompatible with Special Relativity (SR). So as SR is proven to be correct, therefore presentism is wrong. As a scientific realist, and a presentist, this is an important topic to me. Do I have to abandon one or the other? I think not, and I hope that this will be of interest to others here, and spark a discussion... Firstly, the statement "SR is proven to be correct, therefore presentism is wrong" is a gross oversimplification. I suggest that we need to dig a little deeper by asking: 1. What does "SR is proven to be correct" mean? 2. What aspects of SR conflict with presentism? 3. What is the ontological status of those aspects of SR that are incompatible with presentism? Any thoughts? |
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swstephe
Tenured Poster  Usergroup: Moderators Joined: Apr 20, 2006 Location: Borneo Island ... no, really Total Topics: 30 Total Posts: 4099 |
#2
Sounds like "it", (whoever is making this claim), is making a false dichotomy. It is possible that special relativity implies that we never see the exact moment of the present, but we still perceive the moment around us for all practical purposes. Nobody loses sleep over not being able to hear thunder at the same time as a flash of lightning, (unless they are in the process of getting struck). Even if special relativity were false, the time delay due to activation speed of neurons means that your news is "outdated" by a small interval anyway. Our brains seem to be hard-wired to automatically compensate for this delay, which is far more significant than the difference experienced due to special relativity for anything that realistically matters. Actually, you can take special relativity in 2 directions. Either everything you experience is from an extremely close moment in the past, that no longer exists -- you can't be truly aware of something that is really happening, but can assume it is about the same as what you see -- *or* you can assume that your "present" is part of an event cone surrounding you and what you see is a part of your "present". For example, the sun up in the sky that you see is in your "present" and the metaphysical sun from 8 minutes in the future simply doesn't exist for you yet, (and might be at different time phases for others). I think a presentist would prefer to accept the first. I do seem to remember a process where you people ask me questions and I give you answers, and then I ask you questions and you give me answers, and that's the way we find out things. I think I read that in a manual somewhere. -- Haywood Floyd 2010 |
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jedaisoul
exponent of reason Usergroup: Members Joined: Aug 14, 2008 Location: UK Total Topics: 13 Total Posts: 700 |
#3
swstephe wrote: Sounds like "it", (whoever is making this claim), is making a false dichotomy. It is possible that special relativity implies that we never see the exact moment of the present, but we still perceive the moment around us for all practical purposes. I agree that this is a false dichotomy, as the situation is more complex than one is right therefore the other is wrong. However, SR is not about whether we see the the exact moment of the present. It's about whether time actually passes more slowly in certain circumstances, and whether events that occur simultaneously to one observer occur simultaneously to another. So it's not about when the observers see the events, it's about when they objectively happen. At least, that's my understanding... Edited by jedaisoul on Nov 23, 2009 - 4:29 AM |
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Kwalish Kid
Tenured Poster Usergroup: Members Joined: Sep 26, 2004 Total Topics: 38 Total Posts: 4289 |
#4
jedaisoul wrote: I agree that this is a false dichotomy, as the situation is more complex than one is right therefore the other is wrong. However, SR is not about whether we see the the exact moment of the present. It's about whether time actually passes more slowly in certain circumstances, But SR does not say that time passes more slowly under certain circumstances, it says that causal relationships between events is determined by the relative velocity between those events according to any properly constructed frame of reference. We can always create a coordinate system in which, at least for a moment, time is passing perfectly normally for any given event or object. and whether events that occur simultaneously to one observer occur simultaneously to another. So it's not about when the observers see the events, it's about when they objectively happen. Observers are free to determine what is simultaneous to them because they are free to use whatever coordinate system that they wish. It often is easier to use some coordinate systems than others. When I am in the car, I use a coordinate system that is co-moving with a particular stretch of road. Fortunately, there is little difference between simultaneity in that frame and in the frame I default to when I am not moving. One thing that follows from SR is that we are free to assign a kind of simultaneity to events that are not in a causal relationship to each other. Between events with a causal relationship, we can only say that one is in the future of another (equivalent to saying that, for one, another is in the past). Regardless of what coordinate system we use, for a given event all coordinate systems share the same causal past and the same causal future for that event. But there are also a host of other events that are neither past nor future for our given event but that may be assigned a coordinate position of past or future as we wish. From moment to moment, the space around us is filled with points that were in causal contact with us and that will be again very, very shortly, but which are at a given moment not influencing us. We are our own island of the present, just as any object is its own island of the present. But I don't see that this means that the present doesn't exist. Probably done with philosophy. Will check PMs from time to time. |
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Postmodern Beatnik
Castigat ridendo mores  Usergroup: Administrators Joined: Nov 18, 2005 Total Topics: 19 Total Posts: 3137 |
#5
The simplest and best response is that the math works out regardless of whether one assumes the metaphysics of Presentism or the metaphysics of Eternalism. As the math ultimately forms the ground of all the various relativity-based arguments against Presentism, this single point diffuses each and every one of them. "All moral rules must be tested by examining whether they tend to realize ends that we desire. I say ends that we desire, not ends that we ought to desire. What we 'ought' to desire is merely what someone else wishes us to desire." --Bertrand Russell |
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jedaisoul
exponent of reason Usergroup: Members Joined: Aug 14, 2008 Location: UK Total Topics: 13 Total Posts: 700 |
#6
Kwalish Kid wrote: But SR does not say that time passes more slowly under certain circumstances, it says that causal relationships between events is determined by the relative velocity between those events according to any properly constructed frame of reference. Sorry if that sounded pretty dumb. I don't know what level to pitch my conversation at in this forum, so I pitched it fairly low. I had no intention to insult anyone's intelligence, or knowledge of SR. Kwalish Kid wrote: We can always create a coordinate system in which, at least for a moment, time is passing perfectly normally for any given event or object. Agreed. Kwalish Kid wrote: One thing that follows from SR is that we are free to assign a kind of simultaneity to events that are not in a causal relationship to each other. Between events with a causal relationship, we can only say that one is in the future of another (equivalent to saying that, for one, another is in the past). Regardless of what coordinate system we use, for a given event all coordinate systems share the same causal past and the same causal future for that event. But there are also a host of other events that are neither past nor future for our given event but that may be assigned a coordinate position of past or future as we wish. Spot on. Events that cannot be causally related have a "spacelike" spacetime relationship. These can have differences in simultaneity. My point is, how real are the differences in simultaneity? If we say that a relationship is ontologically real if it can support causal effects, then, it follows that the differences in simultaneity are not real. If that is an accurate reflection of reality, then the incompatibility between presentism and SR evaporates. But is it an accurate reflection of reality? |
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jedaisoul
exponent of reason Usergroup: Members Joined: Aug 14, 2008 Location: UK Total Topics: 13 Total Posts: 700 |
#7
Postmodern Beatnik wrote: The simplest and best response is that the math works out regardless of whether one assumes the metaphysics of Presentism or the metaphysics of Eternalism. As the math ultimately forms the ground of all the various relativity-based arguments against Presentism, this single point diffuses each and every one of them. Yes and no. The problem is that the maths suggests that "spacelike" spacetime relationships can have differences in simultaneity. If those differences in simultaneity are ontologically real, then presentism is untenable. At least, that is my understanding... |
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Simple Occam
Professor Usergroup: Members Joined: May 14, 2007 Total Topics: 10 Total Posts: 764 |
#8
jedaisoull wrote: As a scientific realist, and a presentist, this is an important topic to me. Do I have to abandon one or the other? ... The problem is that the maths suggests that "spacelike" spacetime relationships can have differences in simultaneity. If those differences in simultaneity are ontologically real, then presentism is untenable. At least, that is my understanding... Yes, I think you do have to abandon scientific realism or presentism. I'll explain by answering your questions. 1. What does "SR is proven to be correct" mean? A scientific realist believes that the reality that underlies and causes the world that we experience (and want to explain) consists of the entities postulated by scientific theories. So to say that SR is proven to be correct is just to say that scientisits agree that there is too much evidence for it not to be true somehow. After all, believing it enables extremely precise predictions that are confirmed again and again. Moreover, SG and GR along with QM are assumed to be true by other sciences and enable new discoveries in those disciplines, too. 2. What aspects of SR conflict with presentism? I think we agree that SR implies a spacetime ontology, if it implies any ontology at all. But the ontology of spacetime is a true and accurate reflection of reality if and only if absolute simultaneity is false. So, if those differences in simultaneity are ontologically real, then the belief in the existence of the present moment (i.e., presentism) is false. Not just at relatvistic distances and speeds, where things are not causally related, but always... in the eternal now of Eternalism... and everywhere. At least, that is my understanding... But what person reading this can doubt the reality of the present moment in which he or she is using a scientific theory to conclude that Presentism is false ... or true? Of course, this is a rhetorical question but I ask it to suggest that belief in the existence of the present moment is not one we can easily give up. It's a very basic intuition about the world, one that we always had before SR/GR and other abstract scientific and non-scientific theories came along and one that persists in the way we continue to experience reality. Either this very basic belief is false or spacetime is. But which should we prefer and why? Whether any ontology is true or not cannot be decided by appealing to mathematics (deductive reasoning), basic common sense intuitions or scientific theories. Yet you ask 3. What is the ontological status of those aspects of SR that are incompatible with presentism? ... as if we could come up with some kind of meaningful and rational answer. You want to show that the differences in simultaneity are somehow not real, so as to preserve the compatibility of scientific realism and presentism, both of which you accept as true. But scientific realism confirms and relies on SR/GR which entail that simultaneity is relative to intertial or accelerated refrerence frames. There is no "now" that exists everywhere. Since presentism is such a basic and unshakable belief, I prefer to abandon scientific realism and seek another ontological explanation ... one that does not derive from science but explains the truth of its laws in a deeper way that is no less empirical than the scientific method. I'd be interested in your thoughts. Edited by Simple Occam on Nov 23, 2009 - 8:32 PM |
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Kwalish Kid
Tenured Poster Usergroup: Members Joined: Sep 26, 2004 Total Topics: 38 Total Posts: 4289 |
#9
jedaisoul wrote: Yes and no. The problem is that the maths suggests that "spacelike" spacetime relationships can have differences in simultaneity. If those differences in simultaneity are ontologically real, then presentism is untenable. At least, that is my understanding... What do you mean by "ontologically real"? SR means that there is not one single present moment, but that doesn't mean that there isn't a present moment for each object. Probably done with philosophy. Will check PMs from time to time. |
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jedaisoul
exponent of reason Usergroup: Members Joined: Aug 14, 2008 Location: UK Total Topics: 13 Total Posts: 700 |
#10
Kwalish Kid wrote: What do you mean by "ontologically real"? SR means that there is not one single present moment, but that doesn't mean that there isn't a present moment for each object. By ontologically real I mean an actual physical phenomenon, rather than a mathematical entity that does not correlate to any physical occurrence. I prefer the term "ontologically meaningful", as something may have ontological meaning without "proof" that it is real. I used the term "ontologically real" as I felt that would be more easily understood, albeit less precise. Edited by jedaisoul on Nov 24, 2009 - 1:12 AM |
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