studiot

One of the moderators here is/ was a top notch lawyer. And a very keen mind to boot. But if you don't want to put in the effort I'm sorry but you will have to take things on trust, rather than understand them.

A good way to put it. +1 The way to understabding is to do it in stages, just like modern relativity was developed in stages. To start here is an experiment you can perform for yourself. I have located a point P1 at (X1 , Y1) on an XY plot as shown by the dotted lines to the axes X and Y. Then I have drawn some rotated axes X' and Y' (the dashed axis lines) and again located the coordinates of P1 , now with different values X1' and Y1'. This is shown by the dash-dot chain lines. For the experiment introduce a second point P2 with its own coordinates, as shown. Now either (or better both) measure or calculate the distance between P1 and P2 in both the XY and the X'Y' coordinates. You should be able to convince yourself they are the same. For reference the formulae are [math]{d_{XY}} = \sqrt {{{\left( {{X_2} - {X_1}} \right)}^2} + {{\left( {{Y_2} - {Y_1}} \right)}^2}} [/math] and [math]{d_{X'Y'}} = \sqrt {{{\left( {{X_2}' - {X_1}'} \right)}^2} + {{\left( {{Y_2}' - {Y_1}'} \right)}^2}} [/math] The coordinates themselves measure position, of a single point. You need two points to define (measure) a distance. Both position and distance are properties. Much of modern Physics involves the search for properties that are the same in different coordinate systems. Such properties are called invariants. If you are still interested, we can apply this to time in another post.

I posted an encouraging "go on" because I couldn't make a connection to the extract from my post which you replied to. I am now even more mystified than ever by your response. Well that is only one definition of 'seeing' and contrary to the Scientific Dictionary definition, coinciding with the usage by the John Cutherber camp. However I am glad you joined the fray because I was hoping to ask someone who knows vastly more bioscience than I to pass comment on creatures which are born blind but have eyes which they later develop sight in. I have always stated that there is more than one usage of see. Yes I agee we can see light. One distinct usage I also agree with those who say we can see objects, in the sense of a Cahron Y's reconstruction. Another distince usage I can also see difficulties with both those usages in certain circumstances, if either are presented as the only definition. That is why I have constantly maintained "It's complicated" and provided numerous examples. Here is one for optical illusions. What do you 'see' ?

Go on ?

The OP presumably had a reason for that statement, though we will never know what that reason was. So no, it is not outside the scope of the OP at all. 'Seeing' is a complicated process, as is 'invisibility/visibility' and they not the same thing. I can see with my eyes a certain something that is invisible , but I cannot see it in my minds eye in my brain. We can overcome this by looking at a static picture for as long as we need. Again this is still the basis of many optical illusions.

So there is more than one way of seeing for humans.

If this were true then how would you account for the fact that two humans can look at something and 'see' two different things? This fact is much used in optical illusions.

Isn't ultra modern computing a great step forwards? I can select any size I want (although I shouldn't need to bother) in my Tex editor. When I paste it into the useless new SF editor, those instructions are stripped out. So whatever size I order I get the same sized squashed pizza on my plate (sorry symbols on my screen). But thanks very much for trying, it is not your fault.

I don't think I disagree with anything dru said. My comment was directed at minimal cost/effort solutions. String Junky has exactly the right comment that you breathe out a considerable amount of moisture. But more still comes out of the air as the temperature drops. After standing in the drive for a while, my car often has condensation on the inside of the windows in the current weather The absorbtion and retention process does not only apply to mould substance, it also applies to fabrics, such as covers. In particular it applies to the fabric inner linings of vehicles. The moisture builup in these can easily go stale. All the problems are exacerbated by the confines of the space. So yes a dehumidifier will help. You can also get roof mounted ventilators/ extractors that are often fitted to commercial vehicles that will help a great deal and be better than cracking the windows open a tad. Some of these extractors do not need power, which may be a bonus for you. Boats often have wind powered extractors and small generators, most useful whne they are moored at night. You haven't said if you are on a site with a mains electricity supply. Anything you can do to keep the air moving will help and as I said just a small temperature lift will keep the internal air form a continual condensation cycle.

But I gave you solution in 2nd post.. Except that I had already tried that and it doesn't work. I already said that something here seems to overide the (enhanced) size setting I choose. Thanks anyway. What I don't know is how others see the Tex I am posting but for me it is so small that is muddles up fractions for instance.

I can see one way in which information might require physical substance. That would be in the correct and proper application of Shannon's definition to say a box of chocolates.

I'm sorry I missed this reply of yours before. This is a very busy thread. I do like this reply, +1 to reduce your red mark score. Yes your database contains the information you originally put in. But it also constains the logical connections between the stuff in your database that enable you to use it efficiently. And yes your database requires physical objects to hold it. Now here is a question. Before you assembled your database, all the input data existed somewhere else. Since the data existed the logical connections must have also existed, even if they were not accessible because the data was widely separated. No additional physical entities were required for these logical connections to exist before your database, they just did. So how are you accounting for this? @Steveupson To answer the underlined question consider this The position information available via spactime is a particular type of position, mathematically available because spacetime is a metric space (that means it has a distance function). Pure topological space do not have a distance function yet allow the specification of topological position. For example The yolk is inside the egg. The pips are inside the orange. Manchester City are first in the football league table. The number 3 is third in the following ordered set listing {27, 1, 3, 59}. Also I don't know if you realise that even completely empty space has other physical properties than distance. For example it has an electrical impedance of 377 ohms. As a matter of fact this is independent of distance or position.

80% seems high to me. Here is my 'comfort zone' desktop humidity meter. A camper van you say? One thing to realise is that you don't need to raise the temperature very far to dramatically change the conditons for comfort or against mould. a half to one and a half degress c is plenty. That is ebcause the actual temp and humidity is not static but always fluctuating slightly. As the temp drop some mositure condenses out and gives the mould spores a change to germinate and grow. When the temp rises back the moisture re-evaporates, but the damage is done. This is a self reinforcing cyclic process. You can get very low wattage heaters to run all the time in your enclosed space to maintaint the temp this much above ambient. That will keep the mould away at reasonable cost.

+1 Here is something to think about. What if a theory is wrong? For example There is over 2000 years of information about the four Element theory of the Ancient Greeks, though that theory is now known to be wrong. How does this affect the physical embodiment of either the theory or the history of the theory or the informatuion that asserts the theory is right or wrong. In fact is there any limit to the information that could be stated about said theory? For example In the year 2525, if Man is still alive the Theory will be 2500 yerars old. In the year 3535...... the theory will be 3510 year old In the year 4545...... and so on for ever.

I feel this thread is wandering further and further off topic, which was about information. The rightness or wrongness of a particular physics theory is irrelevant to this.

I owe you an apology. A silly error crept in there. A 1hp motor is 3/4 of a kilowatt silly me. The rest is correct.

If I stood at the field gate and said to the farmer "do you see the silhouette", he would rightly think I'd had too much cider. Did you see the recent lunar eclipse? What did you see?

Mine is perfect

See my post above.

Always? When we see the black sheepdog, What light do our eyes receive from the dog? Yet we correctly 'see' a dog, not an absence of light (can you see an abscence of light?) I think counterexamples can be constructed for any simplified definition.

I see no inconsistency. There are many terms where one word can mean the whole or part of something. For instance sheep can refer to one sheep or the whole flock. But if you are looking at a field of sheep, you need the context to distinguish which is meant. Baa Baa Baa

Conversion / connection / some other word. I suppose different people have used different words for much the same thing. Here is a simple example. A 3/4 hp (750 watt) motor runs at full power for 4 hours. How much energy does it ouput? (ignoring efficiency considerations) Well power x time gives energy So in units the output is (3/4 kilowats-hours) x 4 = 3 kilowatt-hours of energy on your meter or 3 units of energy. In dimensions we have Power x time = energy (ML2T-3 ) x (T) = MLT-2 Would you call that converting power to energy usage?

Hopefully it was helpful. It is important to get this because this thread is posted in relativity and when you move to spacetime, you need the conversion. Spacetime is not three spatial axes plus one time axis. It is four equivalent axes, so the added time part must be 'converted' to a spatial axis. At the risk of introducing one more difficulty, the easiest way is to use the imaginary number [math]i = \sqrt { - 1} [/math] Because the pythagorean theorem about distance distance in ordinary space [math]{\rm{distance}} = \sqrt {{x^2} + {y^2} + {z^2}} [/math] becomes [math]{\rm{Interval = }}\sqrt {{x^2} + {y^2} + {z^2} + {{\left( {ict} \right)}^2}} [/math] When the (ict) bit is squared the necessary negative sign appears naturally due to the square root of minus 1 In ordinary space the distance is the same in all coordinate systems (frames). That is it is invariant. The becomes the interval is the same in all coordinate systems (frames). That is it is invariant for spacetime.

The only thing I did wrong was to write the equation E = mc2 with a capital M, sorry. Yes you have got it (how did you get on with the link?) @sensei No I don't care what nonsense Wiki says. Units are things like kilogrammes, metres, miles centuries etc. Dimensions are not specific to particular units. In particular the constant of conversion is never included in the dimensions but must be included in any comparative statement of units. For example there are 1609.34 metres in one mile. Both miles and metres have the dimension L So the constant of conversion (=1609.34) is miles divided by metres which is L/L and therefore dimensionless But the point I'm making in answer to geordie is that the constant of conversion, which provides the connection he was seeking, between space and time, is a speed. In particular it is the speed of light, c

The equation is just a simple high school quadratic with some unusual numbers in the coefficients. The solution could be obtained using the usual formula. I did this because I wanted to be sure no one had ever bothered to actually obtain the solution for real. Please remember also that the phrase "There exists" Has quite a different meaning in Mathematics and Physics. You can often even prove the mathematical existence of something (mathematical), without actually finding it. But in Physics youhave to find it before you can claim its existence for definite. The recent search for the Higgs Boson is a famous case in point.