Graeme M

Interesting. I hadn't realised ice is 10% larger by volume, I'd assumed the effect would be very small. That is a lot. I did however dig around and find this: http://www.skepticalscience.com/Sea-level-rise-due-to-floating-ice.html Which refers to a paper by Noerdlinger and Brower ( http://www.ingentaconnect.com/content/bsc/gji/2007/00000170/00000001/art00010). I tried to think through the whole thing but got too confused, however I do think melting sea ice will add volume even if only a very small amount. I guess I think of it from a practical perspective. A volume of ice floating in seawater should ride higher than in freshwater due to the greater density of the sea water. If I push the ice down into the sea water to the same level as it would ride in fresh water, it must displace some volume of water. It follows that when it melts it must add volume. But then I think, hang on, the water will then become denser. That's when I get confused! Either way, it's been an interesting thing to think about.

On a climate change blog I recently had a brief exchange in relation to melting sea ice. I argued that melting sea ice must add to sea level rise. Others maintained that floating sea ice cannot add to sea level when it melts because it displaces the same weight of water as it weighs itself. I wonder if people who know more about the physics of buoyancy etc can explain which view is correct? I have done some research and come across arguments in both directions but many seem to view buoyancy in a way fundamentally different from how I look at it. One caveat - I know nothing about sea ice, but I assume that it floats, and that some portion is proud of the sea surface. I don't know how much but that it does is why we have ice-breakers. My understanding is that buoyancy and displacement are related but not the same thing. Buoyancy is the extent to which an object in water is prevented by the buoyant force from being accelerated down by gravity. The buoyant force is due to the pressure differential between the top and bottom of an object and can be considered equivalent to the weight of the volume of water displaced by the object. Displacement is the volume of water displaced by that volume of an object which is submerged. The density of an object will determine whether it floats or not, given sufficient body of water. In the case of fresh or pure water, an ice block in the shape of a cube should float with its top surface flush with the water surface (assuming no impurities, or air trapped in the block). It cannot do otherwise as the buoyant force will be exactly equal to its weight once it is completely submerged. When we do an experiment at home along these lines various other factors come into play, such as air trapped in the cube or accuracy of measurement at such small scale, however generally speaking we should find that a melting ice cube doesn't have any appreciable effect on the water level in a container. I expect that the internal molecular structure must have some influence, for example a block of ice might be slightly less dense than the equivalent volume of water, but I don't actually know how the structure is affected by being frozen. I suspect however that at the macro level the difference is negligible - a body of water is of mass X whether it's liquid or solid and the relative densities are almost the same. However, sea water is salty and has various impurities. As I understand it, frozen sea water (sea ice) is fresher as the salt precipitates out as it freezes, and this process continues over time. Older sea ice is thus more 'fresh' than new sea ice which is itself more 'fresh' than sea water. For this reason, sea ice floats. That is, a volume of sea water is denser than an equivalent volume of sea ice - it has additional mass from the presence of salts and other impurities. Looked at another way, the molecules of salt etc are more dense (have more mass) than water molecules, so a given volume of sea water weighs more than an equivalent volume of fresh water. Equally however, equivalent volumes of each should have different quantities of actual water - the sea water has less water per volume than fresh water. When sea ice forms, it is fresher than sea water, and hence less dense, and therefore floats. The buoyant force is equal to the weight of the volume of water it displaces. If for example a sheet of sea ice is 5 metres thick, it may be that 4.5 metres is below the surface, and .5 metres above the surface. The volume of sea water displaced by the volume of ice beneath the surface is less than the total volume of the ice sheet, but its weight is sufficient (by way of its greater density) to offset the weight of the whole ice sheet. This means that the mass of the displaced sea water is equivalent to the mass of the whole sea ice sheet, but its volume is less. When the sea ice melts, the total mass of water plus now melted ice remains the same but the volume of the sea water increases and the sea level must rise. I imagine the effect to be quite small, but nonetheless I believe it must be a positive value. Am I right or wrong?

You still seem to have the idea that "you" is somehow a separate discrete thing. If I take a cup and use the transporter, I get a perfect copy of a cup. Or if I have some kind of duplicator, same thing. The original and the copy are identical. They have different atoms it is true, but they are identical. There is no possible test other than atomic assessment that will uncover the difference. At a macro, functional scale, they are identical. There is no 'special' cup. They do the same thing. There is nothing you could do with one cup that you could not so with the other cup. So too with a person. That's all there is to it. Yes, in the original experiment where the original dies, "you" died. That is, the physical being was vaporised and the "you" emergent in his brain ceased to exist. However the copy on being created generated a new instance of "you" in his brain. The point being made is that while that physical being is a copy, a new one so to speak, the you in his brain is not a new one, it's exactly the same thing. You just emerge from the function of the brain in the same way that "capacity" or "function" emerge from the structure of the cup. Thus, while original you dies, copied you is aware of the world and quite happy to be you. But look, I know what you are getting at. It's what's illustrated by the matter of creating say 100 copies and having them all co-exist with the original. While I get that each is me, I still think that the experience of each is quite attractive to each and the fact that there are 99 others is little comfort to the one I kill.

Well TAR I'm not going to pretend my idea here is actually RIGHT. It's a thought experiment to illustrate ideas about self. The idea being expressed here, to which I subscribe, is that there isn't actually a disembodied self or soul (or even embodied self or soul). The sense of self arises due to the brain generating a particular representation of its internal state, and this representation is generated moment by moment. This means that the representation which you perceive as you depends on the way your brain is wired to connect the dots so to speak. But the connection of dots is a finite thing, even if there are a trillion possible combinations of connections. If we simply recreate that arrangement elsewhere, then theoretically "you" spring into being. It's not magic and it's not transporting some ethereal essence, it's just that a brain of a particular configuration gives rise to you, and it will regardless of where that brain is. Of course if there are two of them and they go on living, the arrangements change and the internal representations diverge, but then both diverge from the original pre-copied version of you too.

TAR, I think we are sort of going in circles here. It seems we are all agreed that a perfect copy is still a copy, or maybe more exactly it's a distinct separate being. It's made of different atoms and so on. So all that you say is correct - the copy is separate. It has its own experience. Neither can 'read' the mind of the other. Each can be aware of their particular existence (ie as 'original' or 'copy') and so on. The idea that some are getting at is that there is no ethereal 'something' which needs to be transferred between each. There isn't a "you" in the original that remains you and is not accessible to the copy. You simply emerges from the function of the brain. If a perfect copy is made, the copy will come with all of the various arrangements of the brain exactly the same. That means that in the first moment after the copy is generated, copy and original are identical. Each has the exact same identical "you-ness", the experience of each is identical. There is no longer a privileged you. From that moment on, experiences diverge. But the original and the copy are now equally as different from each other as from the original before the copying. The brain constructs you in each moment from the sum of its perceptual input and internal data such as memories. So everyone is simply saying that the you in the copy is as much you as the you in the original. Consider a single typical you. The brain creates you afresh in every moment from the information it has available to it. You are just an arrangement of neural connections. In your case, you are aware of your you-ness - you are 61 years old, went to a school in Newark, worked with Fax machines and so on. Now, imagine damage to your brain from a blow wipes all memories of your earlier life and you awaken in some new city. If you never recover your memories and no-one ever tells you of your previous life, are you still the same you? There is a physical continuity of being it is true, but of the mind or self arising therefrom? Imagine if we could alter your brains chemical/physical arrangement and implant all my memories, replacing yours with mine. Not my current processing arrangement, just my memories. Are you still you? If you remember now, inside TAR's head, growing up in Maryborough Australia and working in civil administration, are you really still TAR? You are physically, but in the essence of your conscious experience? I must admit though that while I now get the idea of what it means to simply arise anew in each moment, I can't quite bend my mind around what it means for the transporter idea. On the face of it, if I step into the transporter, am vaporised and then regenerated on Mars, I accept that it will seem I have been transported to Mars. No different to awakening from anaesthetic. That said however, there IS still a specific experience of life that each version has - we ARE aware of ourselves as living beings. Taking Eise's proposition then: "Situation 2 On earth, you step in the transporter, and push the green button. The next moment that you are conscious again and step out of the cabin, you are still on earth. You hear that there was a malfunctioning of the transporter. Your original 'you' (i.e. you) were not immediately destroyed in the process, but the copying worked well and your duplicate has just stepped out of the transporter cabin on Mars. If you want, you can talk with him via telephone. However, due to the scanning process, you will die in the next few days. Are you dying or surviving in situation 2? Would you step in such a device? If you wouldn't, would you in situation 1? Why?" In this case, while my copy is happily enjoying life and his experience is to be me, the original me is still quite well aware of things and is not that keen in dying. I think the only resolution to this is to face the fact that I am not real in a substantial sense. In the case of the properly functioning transporter, the effect really is that I die. "I" just don't notice that because death is not to exist. My copy on awakening just runs my experience and that is good enough. Again, it's no different to when I awaken from anaesthetic. In Eise's case, the distinction is that the process of dying is now rather more apparent to original me. But it is in fact of no more consequence than it was when the transporter worked properly.

TAR, consider this. Do you agree that if I could create a perfect copy of you, then that clone would be in the moment of creation exactly the same as you? That to it, it is TAR, and to you, you are TAR? Disregard here matters of physical unlikelihood, this is a thought experiment only. In practice I am suspicious some kind of quantum effects would make this impossible, but here we are simply considering what it means to have your subjective experience. In the moment of creation then, you and T2 are absolutely convinced you are both TAR. What makes your idea that you are you, any more valid than T2's? Imagine if you will technology that enables us to regenerate T2 at every moment of time into the future. Regardless of what he does, every moment of regeneration for T2 comes with all of the subjective experience you have had till then. Or vice versa. Which of you is real TAR?

Indeed yes. It still does my head in a bit trying to quite fathom what that notion means but hey! I'll keep thinking on it. TAR, I think the point I am making is that there is no privileged you. So to speak of you when you talk of the original and copy is erroneous. They remain two separate physical beings it is true and hence as you say neither has access to the other's thoughts or feelings. But each is "you". Or more exactly each is an abstracted model of the brain's processes. You arise at each moment as an entirely new construct. There is no transfer of any ethereal substance any more than there is a transfer of any elbowness between the two, yet each has an identically looking, functioning elbow. So too with the brain. Going back to the OP's question: "We do the exact same thing again but we don't atomise the original "you". There are now two copies of you with the exact same experience up until this moment in time. Which one of them do you experience the world through? Who's experiencing the world through the one that isn't you?" The answer is neither and both. There's no privileged you. Each experiences the world as a separate being with no access to the other's experience, but each is absolutely TAR or Graeme M or whomever was copied.

TAR I don't think we are disagreeing. It's a matter of perspective. I am not saying that there is a you, or an entity, or a ghost in the machine. I am saying there is no you as an entity that exists independently. What we experience as a self is something of an illusion - it's just a neural arrangement. In a way, it's like say a software program. It has no actual self, but a copy of that program can run on any hardware that supports it. So the physical body that is you now, is your body. Destroy it and its gone. Create a copy and you've got a copy. The copy's brain will create a conscious state. Because it has access to your memories etc it will be the same subjective experience as you currently have. Strictly speaking it's not "you" because there IS no you. Qualitatively the subjective experience is the same.

Well, I don't pretend to have suddenly gained the ultimate insight to existence, i was simply noting that on reflection I now agree with several earlier posters with whom I was arguing. So, in saying what I have, I am just saying I have a particular opinion. I may still be quite wrong to hold that opinion. That said, after reading several recent books in the meantime, my general idea of how consciousness works is that the brain constructs a model of internal processing and it is this model that we consider to be consciousness. To put it perhaps too simply, consciousness is just what it feels like to have an internal abstraction of the state of the brain's neural network at any point in time. In effect, there isn't a "you" in the traditional sense of you, rather "you" and your subjective experience are simply the constructed model of perceptual object and attentive processing. So in answer to your question, yes, the clone will in that first moment be exactly me, or rather, its neural arrangement will be identical. Thereafter it goes its own way. But that is simply what happens now. At each moment, our internal neural arrangement is what it is in response to sensory input and internal processing. Thus if we created 100 clones, Each would be quite certain it is me and as far as it is concerned, life has just gone on. The point is that it doesn't matter what unfolds into the future, each is simply a Graeme M. Which is just a current state of neural arrangements. That's it. And anyone who has undergone a general anaesthetic has probably experienced this. The brain depends on wide scale connectivity to function and give rise to consciousness. When that connectivity ceases, so does consciousness. And if there is no consciousness, then in effect we cease to exist for that time. There is no abstracted model. On awakening from anaesthetic, the brain reboots and re-establishes the network connectivity and consciousness re-emerges. That is exactly how it feels to die and be reborn. Absent the reawakening part and that is death.

TAR, I have always felt the mind/soul/consciousness simply arises from brain function. I am no dualist. I just hadn't really understood what that meant. I now see consciousness as purely a dynamic neural process. Thus, there IS no continuity in a linear sense, there simply is a current state. That state has access to working and long term memory and so there is a sense of continuity, but not in a literal singular entity sense. So there is no "you" to get anywhere. That was my mistake, I thought there was a specific "me" keyed to my current physical implementation. But I now do not think there is. "I" am simply a brain state, or more exactly I suppose a configuration of neural circuitry that changes moment by moment. In a way, "I" arise anew at each moment. In a more literal sense, there is no "me". Thus if we replicate my exact neural arrangement at any moment on another platform, the consciousness so derived will feel exactly like me.

At the risk of starting this one all over again, I just wanted to note that I now distance myself from my earlier position. I see that I had indeed been arguing, despite my belief otherwise, for a dualist position. I had at heart a distinct notion that Graeme M is a particular entity with an existence that is at once discrete and continuous. Upon reading more and thinking on this, I now agree with the view that there is no me, simply a state of neural processing of sensory and internal state information at any point in time. A perfect replica of me would indeed be me - consciousness wise -as would any number of such replicas. Disregarding what quantum state matters might indicate (simply because I do not know enough about such matters) and assuming at the macro level that the transporter does create a faithful replica of me, I would now happily use it.

I'm wondering if anyone has some further thoughts on this topic as regards a particular aspect of the experiments and data. I've read several more papers on this but something that isn't clear to me is how Libet (and others) have been able to determine the timings according to the subjects own introspective assessments. The times that were recorded were W, M, S and 0, where W is the time the subject perceived the urge to act, M is the time that the act was perceived to occur, S was a time that the subject perceived an electronic stimulus of the skin and 0 was the time of the act according to ECG traces. Subjects were to allow the act (a wrist or finger flexion) to simply occur - that is, to be voluntary and not in response to any external stimulus - and not to prepare or pre-plan the act. Now, if I try this myself, I am simply not aware of any 'urge to act'. I can just sit here and then have my finger flex so I can clearly identify the moment it happens, but an 'urge to act'? Not at all. Even if I try to keep my mind 'clear', I am simply not aware of anything other than the movement. Does anyone have any thoughts on what exactly Libet's subjects might be reporting? Especially when you think it's within 200ms of the act occurring, that's a level of fine temporal distinction I don't think I could do.

Gotta get back to those strange loops! You've about convinced me, I'll see if I can chase up a copy over the weekend. As far as the free will thing, I'm not that's directly my interest, though I suppose it hangs off it. No, I'm more curious about the extent to which we are conscious of our thinking and decision making. Or if you like, does the conscious decision as expressed in my mind result in the behaviour.

I've read those papers Acme, and I like Schurger's argument. Briefly, he argues that random fluctuations in neural activity will tend to approach a threshold over time; once the threshold is exceeded a motor action is decided. This is in respect to voluntary, non temporally constrained decisions to move. In other words, the Libet experiment suggests that for voluntary actions the brain prepares for action BEFORE the conscious decision to act. Hence the urge to act is a post facto addition to experience. Schurger suggests that typical neuronal activity buzzes away and it is not until a threshold point is reached that the decision to act occurs (and the act itself). That is, when we are thinking of doing a voluntary act, the choice of when to act is precipitated by the neural activity exceeding the threshold. The RP curve typical of the Libet experiment simply describes normal activity with the actual motor response grafted on (because a motor response occurred). I think this still suggests that the motor act occurs without conscious direction as such, it serves merely to bring decision point and motor response closer together temporally. But it does show that the decision to act and the act are not separated as such, rather they both arise from the same underlying neural activity. But I also may be misreading the paper. It may be that when the activity reaches close to the threshold it's already primed by an expectation to act at some time, and thus at that point it tips over the edge and causes the conscious decision from which the act arises. Even then though I do not think it rescues us from the sense that the 'voluntary, conscious' act arises unconsciously from a potential. I'd be interested in anyone else's take on this paper and its findings.

Well, that's got to be one of the more amazing things I've come across. Of course I always knew that sound is transferred by vibrations and roughly how an ear and a microphone (and a record stylus) work, but to actually sit down and think about it shows me an underlying complexity that to be honest I can't get my head around. It still seems weird to me that an entire orchestra (for example), doing so many complex movements to generate a whole host of separate sounds, can be replicated by a simple vibrating membrane. I tried to read up on Fourier transforms and how they can unpick the components from a complex waveform and it escapes me completely. On a slightly different tack, the energy used to vibrate the air or fluid is doing work, does that imply that the ear should heat up in loud/complex sound fields? Does air heat up from sound vibrations?