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I'm not sure if this is a question for philosophers or for physicists, but I'll

I'm not sure if this is a question for philosophers or for physicists, but I'll ask it here anyway. Do you think it is possible that there are other universes? I mean "other universe" in a very physical sense: any group of objects that have no past, present or future physical relations to the objects in our universe. For example, they don't originate in the Big Bang. And it is physically impossible that a photon leaves one of such objects and hits one of the objects in our universe. And those objects aren't at any distance from the objects in our universe (it cannot be said truthfully that those objects are or were n light-years away from any star in our universe). But I mean real, actual objects, and not merely "possible objects" (there is a previous answer on this subject in AskPhilosophers, but that's not what interests me)! Do you think that there can exist other universes in this sense?

Let's use a phrase from the philosopher David Lewis: concrete worlds. Let it mean complete, concrete universes. Lewis thought that there are concrete worlds other than our own, and that there is at least one for each way our world could be. Lewis also characterizes these words in the way you do: they aren't in our space-time, so they're not at any spatial or temporal distance from our concrete world, and they don't interact causally with our world. As Lewis understand things, they wouldn't be other worlds if these conditions didn't hold.

Lewis thought there were such things. He thought that making sense of ordinary truths about what's possible calls for them. My admittedly unpopular view is that this is the wrong way to think about possibility. Even if such worlds do exist, there may be (would be, I'd say) non-trivial modal truths about them. Any particular such world might not have existed, for example. Far as I can see,here's no home in Lewis's account of modality for these sorts of possibilities. In fact, I'm tempted to resurrect an old term and say that the Lewis-style way of thinking about possibility amounts to a category mistake.

But that's just me, and at least some of my colleagues would hoot in derision.

Be that as it may, it's one thing to say that these worlds would be the wrong sorts of things for the job Lewis assigns them (and I realize that's not your issue); it's another to say they couldn't exist. I can't think of any good reason to believe that such worlds are flat-out impossible. And though I'm open to persuasion, my instinct is to suspect that any "proof" to the contrary would be sophistical.

This might sound like a simple "yes" to your question, but it's not so simple as that. What's possible and what I seem to be able to describe or imagine may not be the same thing. It may be that, for reasons I'm not grasping, utterly other concrete worlds are not possible. All I can say is that if I were making philosophical bets, I'd go with saying they are. I'm just not sure what my odds would be...

In theory of relativity all relations are derived based on one observer in a

In theory of relativity all relations are derived based on one observer in a moving frame relative to another frame. How statistically relevant it is to make conclusions based on just one observer? Who told it is valid?

I don't quite recognize relativity in what you're saying. Relativity tells us that an experiment in one inertial (non-accelerating) frame will look the same in any other inertial frame (that part also applies to Newtonian physics) and that the speed of light (in a vacuum) is the same in all inertial frames. (That part is a departure form Newtonian physics.) Relativity also tells us how to translate velocities, times, etc. between different inertial frames, and it gives an answer that's different from the Newtonian one. But the evidence for relativity has nothing to do with picking some one observer and giving that observer special status. On the contrary: that would go completely against the point of relativity. Further, there's no question of drawing experimental conclusions of whatever sort based on just one observer. Rather, what relativity says is that whichever observer performs an experiment, his/her state of inertial motion won't affect the physics. Whether the evidence from the observer's experiment is strong enough to let us draw general conclusions is a separate question, and one that has nothing to do with the theory of relativity.

Is length an intrinsic property or is it something which is only relative to

Is length an intrinsic property or is it something which is only relative to other lengths? Is an inch an inch? Or is it simply a relation between other (length) phenomena?

It is indeed an interesting question, and in fact it's more than one question.

To begin with, my colleague is correct: in special relativity, length is like velocity in classical mechanics: it's a "frame-dependent" quantity. However, the theory of relativity is also a theory of absolutes; between any two points in space-time there is a quantity called the interval, and it is not frame-dependent. To put it in the jargon of relativity, the space-time of special relativity has a metric -- a generalized "distance function" -- and that metric delivers an unequivocal answer to the question of whether the interval between w and x is equal to the interval between y and z.

But now we have a new question: suppose that relativity says that the interval between w and x is, in fact, the same as the interval between y and z. What kind of fact is that? Suppose that the two intervals have no overlap. Doing business as usual, so to speak, we come up with the answer that the intervals are equal, but we could use a different metric function that gave a different answer, and by making adjustments elsewhere, we could make the physics work out. The physics that made the adjustments might be more unwieldy; it might involve some peculiar "universal forces," for example. However, it's not immediately clear that this shows the usual way of doing things to be ontologically privileged.

The debate we're now describing has to do with the "conventionality of the metric," and some heavyweight thinkers, not least the philosopher of science Hans Reichenbach, have argued that the metric is indeed conventional. That is, it depends on choices we make that could, in principle, have been made in a different way.

This issue has a connection to questions about meters and such. We pick out a meter by reference to the standard meter stick (or at least, that's how we used to do it.) But there's some complexity here. Suppose I take my own meter stick, lay it against the standard meter, and find that they match. While they're in contact, there's no doubt that they have the same length. But what about when they're not? Does my meter stick retain its "real" length when I move it around? (Leave issues of relativity aside for the moment. We could say things in a more complicated way that took them into account, but the issue would not really change.) Or does it contract or expand? Or is there really no absolute metaphysical fact of the matter? The conventionalists would pick this last option. When we consider the whole package of our physics and our measuring devices and our assumptions about forces, we may say that (absent unusual circumstances) the measuring rod has the same length when it's "here" as it does when it's "there." But the conventionalist would insist that saying this ultimately rests on certain stipulations or conventions.

The literature on this topic is complex, as you might imagine. Even though he argues for one side rather than the other, I'd suggest that Reichenbach's Philosophy of Space and Time is a good place to start. It's an engaging book that's more accessible than it might appear at first sight.

Are equations like F=MA or e=mc squared metaphysical statements about energy and

Are equations like F=MA or e=mc squared metaphysical statements about energy and force or are they empirical observations about regularly occurring correlations?

I think you can safely take them either way. You could take them to be more or less definitional of the terms involved. In that case the empirical question would be whether the terms pick out real quantities in nature. Or you could take the terms to pick out independently identifiable quantities and then they would be empirical statements.

What is the philosopher's response to the anthropic principle?

What is the philosopher's response to the anthropic principle? (which, if I recall correctly, states that the universe "had to" evolve in a certain manner, otherwise we would not be here to ask these questions about it!) Is it dismissed as basically a tautology? or is there something more substantive behind it?

It strikes me as neither a tautology nor as something that has anything "more substantive behind it." The tautological version is that the universe did come to be in such a way as we came to be a part of it. But given the number of other animals that have managed to go extinct, I see no natural necessity that the universe simply had to have us in it, or has to have us in it in the future. I reckon the universe would go on pretty much the way it goes now if we managed to go extinct, which also seems to me not just to be possible, but actually likely, long-term. Even where we happen to live, it looks to me like natural reality can get pretty rough on us at times--ask the people living on the coast of New Jersey! Not friendly at all!

Is Kant's project of reconciling freedom with an apparently deterministic nature

Is Kant's project of reconciling freedom with an apparently deterministic nature still relevant given how Quantum mechanics does not (as I understand it) see nature as a deterministic totality?

In my opinion, it's no harder to reconcile freedom (free choice, responsible action) with determinism than to reconcile it with indeterminism. On the contrary, it may be easier; see, for example, this SEP entry. According to compatibilists, we can act freely even if determinism should turn out to be true and hence even if the indeterministic interpretation of quantum mechanics should turn out to be false. But no one thinks that the truth of indeterminism (whether quantum indeterminism or some other kind) by itself would suffice to give us freedom. The debate is about whether indeterminism is necessary for freedom. In my view, incompatibilists bear the burden of showing that it is and have failed to discharge that burden.

Help me know if I have the Big bang theory down correctly. It consists of the

Help me know if I have the Big bang theory down correctly. It consists of the following ideas. 1. The big bang theory is usually or often seen as a naturalistic hypothesis where only physical reality is truly real. 2. The universe is a physical reality. 3. There was no physical reality prior to the universe. 4. The universe began with the Big Bang. 5. There was no universe (or physical reality) prior to the Big Bang. 6. It follows from 1-5 that nothing whatsoever existed prior to the Big Bang. 7. The objection of so how did the universe come about if there was nothing prior to the big bang is that time only began with the big bang. To speak of a beginning implies an occurrence within time. It is therefor circular to say that time began with the beginning(of time). I think that what is happening here is that a rejection of (traditional metaphysical)philosophy and even common sense means that science has become a new form of irrational religion in our day. What do you philosophers have to say about this?...

I'd say that you don't have the Big Bang theory down correctly if by the Big Bang Theory you mean what physicists mean. Whether a physicist accepts some version of the Big Bang account as a piece of physical cosmology and whether the physicist believes that nothing is real except for the physical are two different questions. Some physicist (perhaps even most for all I can say) believe that there's nothing outside the physical, but that's not a claim within physics. It's a metaphysical claim that the Big Bang hypothesis doesn't settle.

But suppose we're physicalists (i.e, suppose we think only the physical is real.) Is the combination of physicalism and the Big Bang inconsistent?

I don't see why.

You say that to speak of a beginning implies an occurrence within time. Let's concede that; it's logically harmless. The first moment, if there was one, was, of course, a moment in time. If time began, it began with the beginning; we can agree that this is circular (or better: a tautology.) But "Time had a beginning" is not a tautology at all, and the claim that there were no moments before the big bang is anything but circular. (It may be false; that's a scientific question. But the very fact that it could be false is proof that it's not a tautology.)

The idea that there was a first moment is peculiar the first few times you hear it. Once you get used to the fact that modern cosmology routinely appeals to space-time structures that are mathematically well-understood but not what Newton - let alone Euclid - had in mind, the oddness tends to fade away. No contradiction follows from saying that there was a first moment, and even on its face, the claim doesn't seem circular. The fact that "common sense" finds this odd doesn't tell us much; there's a great deal of respectable science that common sense finds odd, but then common sense didn't cut its teeth on the sorts of far-from-common situations that science has taught us to deal with.

Take the case of a box sitting on a table. In an introductory physics course, we

Take the case of a box sitting on a table. In an introductory physics course, we'd say that there are two forces acting on the box: the force of gravity, pulling it down; and a normal force of precisely equal magnitude, pushing it up. Is there any real difference, though, between saying that there is no net force acting on a body, and saying that no forces are acting on it at all?

Sure there's a real difference. The first account implies that the box is being compressed vertically because gravity acts on all its parts (molecules) whereas the opposing force is acting on its bottom surface (where it touches the table). The second account implies that there is no such compression, that the box, even if it is somewhat elastic, has the same height when it is sitting on the table as when it is floating in outer space. The first account -- correctly -- implies the opposite: that the (not perfectly rigid) box is slightly less tall when it is sitting on the table than when it is floating in space.

The first account is also more elegant in this sense. Suppose the table is forcefully kicked out from under the box so that the box starts falling. The first account can easily explain this by pointing out that, with the table out of the way, the gravitational force now acts unopposed. The second account has to say -- oddly -- that the kicking away of the table somehow brings a gravitational force into existence.

Cartesian dualism relies upon two substances, body and mind, which are totally

Cartesian dualism relies upon two substances, body and mind, which are totally distinguished by their properties. While the characteristic nature of body is Extendedness, the mind is known with its capability of thinking. So, Cartesian Dualism is founded on these two basic propositions: 1. All bodies are extended. And 2. All minds are thinkable. Abandoning the latter, the former (1) seems acceptable to all physicalists. But if so, then its contraposition might be true equally. In other words, physicalists should be agreed with this proposition too: 3. All non-extended are non-body The question is how physicalists justify this proposition? In other hand, the unavoidable consequence of this proposition (and its truth) is existence of a non-extended (entity) which isn't body, which isn't justifiable in reductive physicalism approach. So, considering this proposition that in reductive physicalism approach: 4. everything has identify with physics. But, isn’t paradoxical acceptance of (3) and (4)...

Dear Borhan,

The answer to your question requires some deductive logic. Let's start with (1) all bodies are extended, which is Descartes' premise. It follows logically that if something is not extended, then it is not a body. Thus (3) follows logically from (1). You are worried because you think that (3) assumes that something is not extended. But it does not. It only claims that IF something is non extended then it is also not a body. So physicalists can agree with the claim.

Do the developments in quantum mechanics (i.e. the best we can do on a very

Do the developments in quantum mechanics (i.e. the best we can do on a very micro level is give probability distributions), really have anything to say about free will? It might mean that determinism isn't true (although there could be a weaker "probabilistic determinism" that gives the likelihood of different possible events), but introducing chance into the equation isn't helpful to free will either.

Also agreed.

Here is an argument that determinism doesn’t undermine, butenhances, free will.

(1) Our actions are caused by our propositional attitudes,such as desire, hope, acceptance and belief.

(2) The more deterministic the relationship between out attitudesand our actions, the more freedom of will we possess.

(4) The more control we have over our own attitudes the morefreedom of will we possess.

(5) Our control overown attitudes consists in the influence of some of our attitudes over others.E.g. We want to smoke. We also want not to smoke (These are called first-orderdesires) And we want not to want tosmoke and we do not want to want to smoke. (These are called second-orderdesires) We have freedom of the will toextent that our desire not to want to smoke wins out. (From ‘Freedom of theWill and the Concept of a Person’, Harry Frankfurt, The Journal of Philosophy,1971).

(6) The more deterministic the relationship between oursecond-order desires and our first-order desires, the more freedom of will wepossess.

(7) Determinism is irrelevant to freedom of the will in allother respects. It doesn’t matter how our attitudes got there – whether byrandom processes or deterministic ones, they are as they are. And we want themto be in control of our minds and our bodies – for self-management and managementof the external world, as far as possible.

Good self-management – looking after your own desires,emotions and reactions to things is a healthy Stoic philosophy. If you feel yourselfgetting angry and resentful ask yourself why you feel this way – for example: isyour pride affected, or your self-esteem or do you feel threatened in someother way? Ask yourself whether you might have done something to bring aboutthe situation that angers you. Ask whether realistically there is somethingconstructive that can be done to rectify matters. If vengeful thoughts arise,recognize them and banish them. No good can be achieved by vengeance. Harm toyourself would result fro, any attempts at revenge. If there is somethingconstructive to be done, decide whether to do it. If you decide to do it, doit. If you decide not to, let the matter pass and move on. Consider that youyourself would prefer peace of mind than the disturbance of the anger. In thisway you can exert some control over your own mind and attain a more sereneexistence.

Also I have heard tell that quantum laws fix the probabilityof any event’s occurring. No self or soul or will can affect theseprobabilities without violating physical laws.

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