Can Physicalism be defined non-instrumentally?

[Terrapin Station]

If an object is growing, then bits on one side of it are moving away from bits on the other side of it. Agreed, surely?

No, not agreed. There are no "bits" in the case presented. It's one lump with nothing separable. That's what "indivisible" means.

Can you acknowledge that we could measure a one-meter indivisible, etc. sphere where we're not measuring the distance between parts?

[Steve3007]

No, not agreed.

OK. I'll have to give up then. I see no point in continuing with more long conversation in which the result of me answering your questions, and you ignoring mine, is more long fruitless argument at the end of which you'll talk more about pulling teeth and me apparently avoiding answering your questions.

[Terrapin Station]

No, not agreed.

OK. I'll have to give up then. I see no point in continuing with more long conversation in which the result of me answering your questions, and you ignoring mine, is more long fruitless argument at the end of which you'll talk more about pulling teeth and me apparently avoiding answering your questions.

Seeing it as being about "bits" is not considering the thought experiment as presented.

[Gertie]

Apologies if you've already covered this.

What does the ''point'' in ''point-based'' refer to?

It refers to zero-dimensional objects.

And what is the current scientific theory of the most fundamental nature of the universe?

There is no such thing. Of course, there are the standard model, relativity theory, and quantum mechanics; but what the fundamental, ultimate nature or structure of the universe is is still an open question.

I've seen the notion of wave fields 'collapsing' into material particles with specific locations, but I don't understand what they are thought to be waves or fields of?

If you could explain in simple lay terms that would be great - I am a simple lay person!

There are so-called collapse theories in quantum physics. What is said to "collapse" is the wave-function, which isn't a physical field in 3D space but a mathematical field in the higher-dimensional 3N configuration space. But what about (the local distribution of) matter in physical 3D space? Two different ontologies have been developed for collapse theories: flash ontology & matter-density ontology.

(Remark: John Bell coined the phrase "local beable". A local beable is a local material/physical entity in physical 3D space/spacetime.)

1. According to flash ontology, the presence of matter or material objects in 3D space (as that which corresponds physically to the collapse of the mathematical wave-function) consists in the (rare and sparse) occurrence of point-events called flashes:

QUOTE>
"The GRW [Ghirardi–Rimini–Weber theory] dynamics for the quantum state can be conjoined with several different postulates about local beables, thereby creating several different physical theories. Our rather glib talk of the GRW theory has been inaccurate. So far, I have presented only the GRW dynamics for the quantum state. We must now consider alternative ways to fill out the theory with local beables.

When John Bell presented the theory in his article “Are There Quantum Jumps?” he was precise about the local beables he was positing. It is a surprising choice for the material occupants of space-time, which has since become known as the flash ontology.
It is best to let Bell speak for himself:
—
There is nothing in this theory but the wavefunction [Bell uses the term “theory” to refer to the mathematical formalism, as will become clear]. It is in the wavefunction that we must find an image of the physical world, and in particular of the arrangement of things in ordinary three-dimensional space. But the wavefunction as a whole lives in a much bigger space, of 3N-dimensions. It makes no sense to ask for the amplitude or phase or whatever of the wavefunction at a point in ordinary space. It has neither amplitude nor phase nor anything else until a multitude of points in ordinary three-space [i.e., an N-particle configuration] are specified. However, the GRW jumps (which are part of the wavefunction, not something else) are well localized in ordinary space. Indeed each is centered on a particular space- time point (x, t). So we can propose these events as the basis of the ‘local beables’ of the theory. These are the mathematical counterparts in the theory to real events at definite places and times in the real world (as distinct from the many purely mathematical constructions that occur in the working out of physical theories, as distinct from things that may be real but not localized, and as distinct from the ‘observables’ of other formulations of quantum mechanics, for which we have no use here). A piece of matter then is a galaxy of such events. As a schematic psychophysical parallelism we can suppose that our personal experience is more or less directly of events in particular pieces of matter, our brains, which events are in turn correlated with events in our bodies as a whole, and they in turn with events in the outer world.
—
Bell’s flash ontology proposes that the localized material content of space-time is not particles with continuous trajectories, nor continuously distributed fieldlike entities, nor vibrating strings, but rather point events. These points, whose locations correspond to the centers of the Gaussians of the GRW collapses, are scattered quite sparsely through space-time. Recall that an individual electron only suffers a GRW hit once in 10,000,000 years. So according to this theory, overwhelmingly most of the electrons associated with your body make no localized mark on space-time at all in the course of your entire life. They are all reflected in the wavefunction of your body, but nothing in physical space directly indicates their existence.

What, then, would this “galaxy of flashes” look like? Leaving the protons and neutrons (and hence quarks) aside, there are about 10^28 electrons in a human body. That means, just from the electrons, about 10,000,000,000,000 flashes in a single second.
The distribution of these flashes in space would trace out a quite detailed human form. There would be much less to this form in space than we commonly believe, but more than enough to define everything that we take to happen at macroscopic scale. The state of our brains (i.e., the flashes in our brains) would be reliably correlated with this distribution via the same physical mechanism, and thereby we can come to know what is happening around us.

But while the number and density of flashes is sufficient for a finely detailed spatial distribution at the macroscopic scale, it is quite paltry at a microscopic scale. There are about 40,000,000,000,000 cells in a human body, so (at the very rough scale of this estimate) only a few GRW collapses occur per cell per second. The distribution of flashes in space associated with a human body, then, would carry a lot of information about location, shape, and motion at macroscopic scale but almost nothing at the scale of individual cells. Of course, if we go about looking at a cell through even a regular optical microscope, the magnification process would entangle the wavefunction of the individual cell with macroscopic aspects of the equipment (or of the brain of the observer), and the “invisible” parts of the cell would automatically become registered in the GRW flashes.

This tremendous mismatch between what we think is going on spatially in a cell and what is going on according to this theory is extremely disconcerting. Indeed, the flash version of the GRW theory borders on a physical realization of a Cartesian demon, with the wavefunction playing the role of the deceiver orchestrating things. The physics predicts and explains the distribution of objects in space at the macroscopic scale in a way that renders our usual understanding of the goings-on at microscale completely wrong. But since ultimately all our empirical evidence for the theory must exist at the macroscopic scale, the theory still counts as empirically impeccable. Any revulsion toward it is conceptual rather than empirical.

At the start of our investigations, we remarked that physics is the science of matter in motion, that the theory of space-time structure provides the arena for the motion, and that quantum theory should provide the detailed structure of the matter inhabiting space-time. Up until now, we have discussed many experiments that quantum theory must account for, all described (of necessity) at the macroscopic scale. But if the behavior of matter at the macroscopic scale is nothing but the cumulative behavior of its microscopic parts, then a completed rigorous physics should specify what those microscopic local elements are and how they behave. The GRW flash theory is our first complete example of how such a physics might be constructed."

(Maudlin, Tim. Philosophy of Physics: Quantum Theory. Princeton, NJ: Princeton University Press, 2019. pp. 111-4)

"We have already noted that the GRW hits are quite sparse for individual “particles”: most “particles” will not suffer a hit in the entirety of human history. But according to Bell’s proposed set of local beables – since denominated the flash ontology – the only time anything associated with the “particle” exists in space-time is when there is such a hit, such a collapse of the wave-function. So according to the flash ontology, most of the “particles” in your body will leave no mark at all in space-time throughout your lifetime. The collection of local beables in this theory is very sparse indeed."

(Maudlin, Tim. Quantum Non-Locality and Relativity. 3rd ed. Malden, MA. Wiley-Blackwell, 2011. p. 236)

"In short, there is nothing wrong with collapses per se, but a collapse theory needs to give an account of the collapses – both the when and the how – in straightforward physical terms, with no mention of “measurement.”

The GRW theory achieves this feat for non-relativistic quantum mechanics. The general form of the theory is so simple and transparent that one cannot but be amazed that it took over half a century to discover. To the when question, the GRW theory answers: from time to time. More precisely, in the original version of the theory each fundamental particle has a fixed probability per unit time of suffering a GRW collapse or “hit.” The probability for each particle is extremely low: a single particle will experience a collapse on average only once in 108 years. Over the course of all recorded human history, less than 1 percent of particles will have suffered “hits.” The chance of any smallish collection of particles (less than a million) experiencing a hit over the course of a laboratory experiment is negligibly small. This would explain why experiments done on individual particles or small collections of atoms would not yield direct evidence of collapses. The GRW theory solves the problem of specifying the circumstances of collapse by cutting the Gordian knot: there are no circumstances that can either promote or delay a collapse. Instead, one needs a new constant of nature that specifies the mean time between collapses. This constant is subject to some empirical constraints, but at present the value of 10^8 years is compatible with all observations.

As to the question of how, GRW asserts that the effect of a collapse is to localize the wave-function of the hit particle in space. Mathematically, this is achieved by multiplying the wave-function, expressed as a function of space, by a Gaussian (bell curve). Once again, a new constant of nature is required, specifying the shape of the Gaussian, and once again there is at present a range of values compatible with observation. The original GRW paper chooses a width of the Gaussian as about 10^-5 cm, rather larger than the size of an atom but much smaller than a red blood cell. The main requirement is that the Gaussian be narrow enough to resolve any macroscopic ambiguity in the location of a particle. We will return to this topic directly, but let’s first pause to consider what has been accomplished so far.

The source of the measurement problem in standard quantum theory is the appearance of the concept of measurement in the fundamental axioms of the theory. Those axioms specify the dynamics of the wave-function of a system. The GRW dynamics for the wave-function, in contrast, are fully specified without any mention, direct or oblique, of measurements. Most of the time, the wave-function of a small collection of particles evolves in accordance with the usual deterministic linear dynamics (Schrödinger’s equation). The deviations from this evolution, the “hits,” occur at random, with fixed probability per unit time. The locations of the hits are also at random, but they are more likely to be centered at locations where the squared amplitude of the wave-function is higher. The effect of a hit on the wavefunction is always the same: multiplication by a Gaussian function that is rather narrow at macroscopic scale."

(Maudlin, Tim. Quantum Non-Locality and Relativity. 3rd ed. Malden, MA. Wiley-Blackwell, 2011. pp. 226-7)
<QUOTE

2. According to matter-density ontology, the presence of matter or material objects in 3D space (as that which corresponds physically to the collapse of the mathematical wave-function) consists in local spikes in space-pervading matter-density fields, i.e. in tiny regions of space where the value of the matter density is or becomes extremely high. (So the matter-density ontology could alternatively be called field-spike ontology.)

QUOTE>
"The problem of local beables arises acutely for the GRW collapse theory in part because the construction of the theory tightly follows the structure of the quantum recipe. The recipe, in turn, provides clear mathematical expression only for the wavefunction and its smooth linear Schrödinger evolution. GRW replaces the vague “assign these probabilities to the possible outcomes of measurement when a measurement occurs” instruction of the recipe with sharp mathematics. But that mathematics still only deals with the dynamics of the wavefunction and, hence, of the quantum state that it represents. Since the quantum state is not a local beable, all this precision has no logical consequences for what the local beables of the theory might be. The only interpretive constraint we have adopted is that the wavefunction be informationally complete, so that the distribution in space-time of whatever local beables we happen to postulate must be determined by it. But this interpretational constraint still leaves a lot of latitude in constructing a theory. Bell’s flash ontology provides one way to complete the construction, using the discreteness and spatiotemporal location of the collapse centers as the key to the local beables. One might say that in the GRW theory, the collapses account for the “particlelike” aspect of the wave-particle duality, and the flash ontology makes use of this in postulating the local beables. But the discreteness of the collapses in time yields a corresponding sparseness of the flashes. Most of the time, there is literally nothing at all material that is localized in space-time.

It is equally natural, beginning with the wavefunction evolving by Schrödinger’s equation, to be impressed by the wavelike aspects of the quantum state and to seek a correspondingly wavelike local beable. As we have remarked, the wavefunction of a single spinless particle is a complex function on physical space-time, so it is easy enough to associate it with a local beable. In such a picture, a single electron in a Double Slit experiment literally spreads out in space, with some of it passing through each slit and the two parts coming together later to interfere. One problem with this picture is accounting for the localized individual mark that eventually forms on the screen. But if we supplement the Schrödinger dynamics with the GRW collapses, this problem seems tractable: When a GRW hit occurs, the spread-out electron gathers itself up in one place, with almost all the density suddenly concentrated within 10^-5 cm of the location where, in the flash ontology, a flash would have occurred. And as a substantial bonus, any other perfectly entangled electrons will experience a similar sudden contraction.

But so far, all this talk of the electron being spread out in space and then suddenly contracting in space is loose talk. The wavefunction of any system with more than one particle is not even mathematically a function over space: it is a function over configuration space. And similarly, the collapse and contraction are not in physical space but in the much higher-dimensional space. So it is not immediately obvious how to use the behavior of the wavefunction in a scheme for postulating a more wavelike local beable.

The problem, essentially, is that the structure of the wavefunction must somehow be projected down from configuration space into physical space, and then the theory must postulate a local beable corresponding to that projection. In such a theory, the GRW collapses will not correspond to the sudden creation of a pointlike local beable, as happens in the flash theory, but rather to a sudden change in the distribution of a continuously distributed beable.

In the nonrelativistic theory, there is an obvious and tempting way to define such a projection. The wavefunction is defined over configuration space, and the squared amplitude of the wavefunction forms, in the mathematical sense, a probability measure over the set of all possible configurations. If we ignore the suggestive word “probability” here, we can just say that the squared amplitude of the wavefunction defines a weighting of various configurations of particles. The natural suggestion, then, is to regard this weighting not as a probability but instead as a measure of how much of each particle is in each configuration. That is, if the squared amplitude of the wavefunction assigns a weight of .25 to a configuration in which a particular electron is on the left and a weight of .75 to a configuration in which that electron is on the right, then somehow .25 of the matter of the electron is on the left and the other .75 of the matter is on the right.

Since each possible configuration assigns an exact position to each particle, the weighting of the configurations can in this way be used to define a matter distribution for each particle. The matter of the particle literally gets smeared out over space. And as the wavefunction evolves in time, the matter distribution correspondingly evolves in time. This is a matter density local ontology of a GRW collapse theory.

The local beables of the matter density theory have none of the peculiarities of the flash ontology. Every particle’s matter always exists and is distributed some way in space. In a Double Slit experiment, the matter density of the electron literally spreads out and passes through each of the slits like a water wave. (In the flash ontology, by contrast, absolutely nothing exists in the space between the two slits and the screen, except on the very, very, very rare occasion when the electron suffers a collapse in transit.) That distribution will never be pointlike in any respect: The GRW collapses tend to concentrate the matter density in certain finite regions but never at a point. The matter density at the microscopic scale may be somewhat more spread out and amorphous than one would have thought, but it will certainly not be sparse. And at macroscopic scale, as with the flash ontology, the matter distribution will correspond to what we believe about where things are. Or at least it does so subject to some caveats.

The main caveat was noticed early on and goes by the name “the tails problem.” The “tails” at issue are the infinitely extended, never-zero tails of the Gaussian that multiplies the wavefunction during a GRW hit. Since the tails are nowhere actually zero, the matter distribution after a hit is never driven to exactly zero anywhere by the hit. To take a concrete example, if a Schrödinger-cat-like macroscopic superposition (1/sqrt2) | right>e | detection>d + (1/sqrt2) | left>e | no detection>d suffers a GRW collapse, the collapse will drive one or the other components of the superposition almost to zero and therefore (given a matter density ontology) will concentrate almost all the matter into one configuration or the other.
That is, the post- hit state will be something like

(1 – e)^(1/2) | right> | detection> – (e)^(1/2) | left> | no detection>|

or (e)^(1/2) | right> | detection> – (1 – e)^(1/2) | left> | no detection>|.

Subsequent hits, which are almost certain to occur on the initially favored configuration, will reduce the stray matter density exponentially lower. But for all that, the low density of extraneous matter will always exist."

(Maudlin, Tim. Philosophy of Physics: Quantum Theory. Princeton, NJ: Princeton University Press, 2019. pp. 115-8)
<QUOTE

Thanks Consul, it's very good of you to take time to do this, much appreciated.

What does the ''point'' in ''point-based'' refer to?

It refers to zero-dimensional objects.

Well I did ask! Is that meaning real zero-dimensional objects existing real 'out there', or is it more like a map reference, a way of noting a location?

And what is the current scientific theory of the most fundamental nature of the universe?

There is no such thing. Of course, there are the standard model, relativity theory, and quantum mechanics; but what the fundamental, ultimate nature or structure of the universe is is still an open question.

Thanks, I sort of knew that. I suppose I was wondering if the Standard Model and forces had been replaced by a more fundamental model of the 'stuff' of the universe, the types of hypotheses you go on to address.

Which is where I was completely out of my depth. Would a very crude summary be that 1. suggests stuff 'flashes' into this 3d world we observe in certain circs. And 2. suggests 'stuff' is the result of spikes or clusters in the field of... something?

(If this is too difficult to answer in the form of an Idiot's Guide, no worries, don't feel obliged to reply).

[Consul]

It refers to zero-dimensional objects.

Well I did ask! Is that meaning real zero-dimensional objects existing real 'out there', or is it more like a map reference, a way of noting a location

The point-based models assume that 0D objects are really "out there" as parts of concrete, physical reality—as space-points, time-points, spacetime-points, matter-points (point-particles), or boundary points of >0D objects.

Thanks, I sort of knew that. I suppose I was wondering if the Standard Model and forces had been replaced by a more fundamental model of the 'stuff' of the universe, the types of hypotheses you go on to address.
Which is where I was completely out of my depth. Would a very crude summary be that 1. suggests stuff 'flashes' into this 3d world we observe in certain circs. And 2. suggests 'stuff' is the result of spikes or clusters in the field of... something?

I'm not an expert in quantum physics either, so I hope I'm describing things correctly: In the case of 1 we have discrete (and rare) mass-flashes in 3D space (which are energy-flashes if mass = energy); and in the case of 2 we have continuous mass-fields with local spikes (high-intensity zones) in 3D space.

QUOTE>
"One could…begin with the GRW [Ghirardi–Rimini–Weber] theory and supplement the field described by the wave function with a distribution of mass density over three-dimensional space, where the mass density in a small three-dimensional region corresponds to the expected mass density in that region predicted by standard quantum mechanics. In this case, a macroscopic object is just a region of relatively high mass density in three-dimensional space. Alternatively, one could supplement GRW with a set of flashes, where a flash is an instantaneous event in three-dimensional space at the center-point of a GRW collapse event. Here a macroscopic object is constituted by an arrangement of flashes in three-dimensional space over a particular period of time (…). These are the "massy" and "flashy" versions of GRW…."

(Lewis, Peter J. Quantum Ontology: A Guide to the Metaphysics of Quantum Mechanics. New York: Oxford University Press, 2016. p. 159)
<QUOTE

[Consul]

By the way, there are different kinds of (in)divisibility:

viewtopic.php?p=359879#p359879

[Steve3007]

By the way, there are different kinds of (in)divisibility:

viewtopic.php?p=359879#p359879

That's an interesting link to a previous brief discussion of the concept of divisibility (which of course quickly degenerated, as these discussions do).

Consider one of Newton's indestructible extended atoms: a miniature corpuscle, perfectly solid, operating in the void. This atom cannot be physically broken apart by any natural force: unlike the grosser bodies aggregated from atoms, it is physically indivisible. Nevertheless, since it is extended it has spatially distinct parts—for instance, it has a left and a right side. So it is formally divisible. Moreover, were someone to consider these halves, they could, in their thought, designate them as two entities individuating them in mental representation, perhaps through diversity of consideration or selective attention. So it is intellectually divisible. Finally, notwithstanding their physical inseparability, there is no logical reason why those spatially distinct halves could not exist separated from one another. God, for instance, could rupture and distance the two halves, or perhaps annihilate the one part while preserving the other. So it is metaphysically divisible.

It is the part that I've highlighted in bold that seems most concerned with what I've been saying over the last few posts. It seems incoherent to me to propose that a spatially extended object cannot be considered to have spatially distinct parts/bits/sections/slices which could be the subject of "selective attention", as the quote above puts it, for the purpose of measurement. As I said, measuring an object with a ruler involves aligning parts/bits/sections/slices of the ruler with parts/bits/sections/slices of the object.

[Gertie]

Well I did ask! Is that meaning real zero-dimensional objects existing real 'out there', or is it more like a map reference, a way of noting a location

The point-based models assume that 0D objects are really "out there" as parts of concrete, physical reality—as space-points, time-points, spacetime-points, matter-points (point-particles), or boundary points of >0D objects.

Thanks, I sort of knew that. I suppose I was wondering if the Standard Model and forces had been replaced by a more fundamental model of the 'stuff' of the universe, the types of hypotheses you go on to address.
Which is where I was completely out of my depth. Would a very crude summary be that 1. suggests stuff 'flashes' into this 3d world we observe in certain circs. And 2. suggests 'stuff' is the result of spikes or clusters in the field of... something?

I'm not an expert in quantum physics either, so I hope I'm describing things correctly: In the case of 1 we have discrete (and rare) mass-flashes in 3D space (which are energy-flashes if mass = energy); and in the case of 2 we have continuous mass-fields with local spikes (high-intensity zones) in 3D space.

QUOTE>
"One could…begin with the GRW [Ghirardi–Rimini–Weber] theory and supplement the field described by the wave function with a distribution of mass density over three-dimensional space, where the mass density in a small three-dimensional region corresponds to the expected mass density in that region predicted by standard quantum mechanics. In this case, a macroscopic object is just a region of relatively high mass density in three-dimensional space. Alternatively, one could supplement GRW with a set of flashes, where a flash is an instantaneous event in three-dimensional space at the center-point of a GRW collapse event. Here a macroscopic object is constituted by an arrangement of flashes in three-dimensional space over a particular period of time (…). These are the "massy" and "flashy" versions of GRW…."

(Lewis, Peter J. Quantum Ontology: A Guide to the Metaphysics of Quantum Mechanics. New York: Oxford University Press, 2016. p. 159)
<QUOTE

Fantastic! I've been struggling to get what these underlying ideas are for ages. Thank you.

[Terrapin Station]

By the way, there are different kinds of (in)divisibility:

viewtopic.php?p=359879#p359879

I made it clear above that I'm talking about what you're calling "physical indivisibility." Mentally thinking of it in particular ways, so that one invents parts mentally, etc., isn't going to make it actually have parts, and since we're not positing that physics has to be as it contingently happens to be, physical indivisibility is the same as metaphysical.

[Terrapin Station]

By the way, there are different kinds of (in)divisibility:

viewtopic.php?p=359879#p359879

That's an interesting link to a previous brief discussion of the concept of divisibility (which of course quickly degenerated, as these discussions do).

Consider one of Newton's indestructible extended atoms: a miniature corpuscle, perfectly solid, operating in the void. This atom cannot be physically broken apart by any natural force: unlike the grosser bodies aggregated from atoms, it is physically indivisible. Nevertheless, since it is extended it has spatially distinct parts—for instance, it has a left and a right side. So it is formally divisible. Moreover, were someone to consider these halves, they could, in their thought, designate them as two entities individuating them in mental representation, perhaps through diversity of consideration or selective attention. So it is intellectually divisible. Finally, notwithstanding their physical inseparability, there is no logical reason why those spatially distinct halves could not exist separated from one another. God, for instance, could rupture and distance the two halves, or perhaps annihilate the one part while preserving the other. So it is metaphysically divisible.

It is the part that I've highlighted in bold that seems most concerned with what I've been saying over the last few posts. It seems incoherent to me to propose that a spatially extended object cannot be considered to have spatially distinct parts/bits/sections/slices which could be the subject of "selective attention", as the quote above puts it, for the purpose of measurement. As I said, measuring an object with a ruler involves aligning parts/bits/sections/slices of the ruler with parts/bits/sections/slices of the object.

If you had actually been paying close attention to my posts, closely reading them, I addressed this:

"That you could look at it and mentally separate just a bit of it doesn't imply that it has parts. Hopefully that's not something you were thinking, but just in case, I'm mentioning it."

[Atla]

The universe doesn't even have parts. The more relevant question is whether or not the universe is pixelated on some minimal scale, like the Planck scale for example (no hologram/simulation fantasy).

[Steve3007]

The universe doesn't even have parts.

So do you want a discussion as to what constitutes a part/bit/section/slice too?

Would you object if, for my part, I refer to the northern and southern hemispheres as parts/bits/sections/slices of the Earth?

[Atla]

The universe doesn't even have parts.

So do you want a discussion as to what constitutes a part/bit/section/slice too?

Would you object if, for my part, I refer to the northern and southern hemispheres as parts/bits/sections/slices of the Earth?

That's perfectly fine as long we aren't doing ontology.

[Steve3007]

That's perfectly fine as long we aren't doing ontology.

OK. So in what field of study is it perfectly fine?

Are you saying that the Earth having two hemispheres is a useful model but is not a truth about the way that the universe is?

If so, can you give an example of something that you regard as an ontological truth?

[Steve3007]

(And why do you always check the "hide my presence" checkbox?)