studiot

So long as this is not meant to mean that space and time are themselves the same, since there are differences.

There are many learning points available in this thread. The OP is trying to learn, not quibble.

https://en.wikipedia.org/wiki/Eddington_experiment#Immediate_impact Or, in other words, are experts also susceptible to, say, a second-order Dunning-Kruger effect? I suggest there is a difference between a quick 'off the cuff' response or something said 'in the heat of the moment' is the same as Dunning Kruger. As I understand D-K (Strange they have the same initials as a famous publisher) the subject repeatedly and steadfastly pursues their own ideas to the exclusion of the thoughts and suggestions of others. You have dealt with the exclusion part, but there is also the repeated and steadfast part.

Firstly the internal resistance of a voltmeter is usually stated as ohms per volt. The per volt refers to the volts at full scale and is fixed for any scale on the meter. Some meters have a fixed value for all scales and therefore a fixed resistance some have only one scale and again therefore a fixed resistance. Everything you have said is correct, including this. However we would normally take the cell in this condition in circuit analysis it is called an ideal voltage source and also applies to alternating voltage sources. The point is that although sometimes we have to consider the internal resistance of the supply (this might also include the circuit board track resistance in high current situations) we usually don't. There is another reason for saying that voltage measurement can introduce errors. You have used only a single resistor, but in a circuit there may be many resistors. Say you have a simple potential divider say 10MΩ to 100kΩ that is a100 to 1 division ratio. It is instructive to calculate the measured voltage drop across each resistor with say 100 volts applied. Can you do this ? Post your attempt and sensei or I will reply.

I don't recall saying any of this, it certainly has little to do with what I wrote.

Back on Earth, combined Phosphorus is a contaminent in iron ore because it makes steel brittle. It is a highly reactive element There is a wealth of information in this article and its references, both chemical and biological. https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0370-44672015000300331

But theory does keep the spacetime interval invariant, just like lightspeed. This is because space and time are not independent (as you would have it) Spacetime embodies the connection between them. If you have X space and Y space they can be independent, in which case they define a plane. But if, say, X2 + Y2 = R2 , then they are no longer independent and you no longer have a plan -- you have a circle. In this case since X and Y are essentially the same both spatial so they have the same characteristics or properties or effects on matter, you can draw it in space. But space and time have some characteristics and effects the same and some different so the condition of dependence is different, leading to different effects on matter.

Which is no doubt why the EU wishes to break International Law and steal our fish ?? I have yet to see any evidence that Boris' Bill breaks any Law national or international. Reporting on this issue is soley by comments from former leave campaigners who would no doubt like to hand the UK over on a plate.

I don't know enough about current trends in the US to assess the level of truth in the proposition that 'America is divorcing itself from Science', or for instance if true when it might have started. I know even less about 19 century Science in America, though I understand that earlier B. Franklin had great standing. In 19 century Europe and in particlar the UK, there was a burgeoning of Science. Much of this was driven by religous men intending in some way to justify God and his teaching. Also during this period many from the arts side were also practioners of Scinece, eg Wordsworth, Coleridge, Browning. I don't see either of these imperatives in much evidence today.

https://www.bbc.co.uk/news/uk-politics-54171571 Would have thought there was more than enough wrong in the USA for Biden to get his teeth into at the moment. If there is no trade deal, one advantage would be further delay in being stuck with US food and agricultural standards and practices, I don't wish to adopt.

Sea levels rise in one place and fall in another, due to tectonic activity and evaporation. This is measurable today (and being measured) in Alaska. It is also important to distinguish between local sea level rise/fall and land level subsidence/rise Unless there is something to provide the additional water for the rise, the levels fall back again fairly smartly. Such additional water is provided for instance by the melting of land borne ice. In the time periods mentioned, divers are beginning to do submarine archaeology on a now submerged land, that existed then in what is now the middle of the North Sea. It was called Doggerland. But it was no advanced civilisation. https://www.google.co.uk/search?source=hp&ei=NRlhX5ysLqmNlwTzlo3YAQ&q=doggerland&oq=doggerland&gs_lcp=CgZwc3ktYWIQAzIFCAAQsQMyAggAMgIIADICCAAyAggAMgIIADIECAAQCjICCAAyAggAMgIIADoICAAQsQMQgwE6CAguELEDEIMBOgsILhCxAxDHARCjAjoOCC4QsQMQxwEQowIQkwI6BQguELEDOgIILjoLCC4QsQMQxwEQrwE6CAguELEDEJMCOgUIABCSAzoICC4QxwEQrwFQwA1YzB5g-iBoAHAAeAGAAegEiAGOGpIBCzAuMi4xLjUuMS4xmAEAoAEBqgEHZ3dzLXdpeg&sclient=psy-ab&ved=0ahUKEwjcmrLX9evrAhWpxoUKHXNLAxsQ4dUDCAg&uact=5 A good source of reliable data about (past, present and future) coastal civilisations and their fates is sypplied by the Californian Professor Brian Fagan in his book The Attacking Ocean. https://www.bloomsbury.com/us/the-attacking-ocean-9781608196920/ 10,000 years further back an ice age prevailed and sea levels were consequently lower. https://www.bbc.co.uk/news/world-europe-54160645 I would very expect strong evidence for a sustained level rise, especially in the wider and deeper ocean as opposed to a shallow sea like the North Sea or the Behring Sea. And I haven't seen it so far in this thread.

It's just a formal procedure for solving simultaneous equations by substitution so that you always follow the same steps. Substitution involves choice.

The OP asked about 'particles' Not sure if comets and asteroids come into this category, and don't you mean meteoroids? Nor am I sure if any part of the Sun's atmousphere prevents sub atomic particles like neutrinos and others from the cosmic background reaching anything.

Gosh I didn't guess my comment would be so controversial. The OP wasn't entirely clear whether he was asking if water only comes from outer space or otherwise or at all. There is water in out space. There is water on Earth today. It would appear that the proto-Earth could not have had free water and I have referenced modern data as to why in the attachment. We now know that water plays a vital role in plate tectonic activity so there is water today within the rocks. So I see no reason why both mechanisms (outgassing from the rocks and later accretion from outer space material) could not have played a role. Both are secondary. The two sources lead to different isotope ratios in the water, but as I said we need more data to be more precise about this.

Really ?

There is not enough evidence or data to be reasonably sure where the water on Earth came from. There are several hypotheses. One is that it came from the solar system beyond Mars (not Mars itself). As we get more meteor and comet material data perhaps it may become clearer.

Yes but even more Earth has an atmosphere that prevents most dangerous particles to reach Earth’s surface, Not sure about this one. What particles from the universe would they be ?

No, and conduit, if used is not required to be metal. Insulated single or multiple bundled are both permitted and used. Insulated single need a conduit. Yes No the US centre tapped bi-phase transformer system is not used. In most installations transformers are not used. The 200 - 240 volts is the interphase voltage and the higher phase voltages are used in Europe for high power, but not in the UK There are different wiring configurations and fusing arrangements in different countries. Most countries separate power and lighting/low power circuitry. The UK favours a ring main system for power and daisy chaining for lighting. Star wiring is permitted. Continental Europe favours star wiring from a central fusebox for power ; some daisy chaining is allowed. Since there is generally no transformer, there is no centre point to earth. In fact in the UK it is illegal to earth the neutral; whilst in the US it is illegal not to earth it ! In Europe the supply company generally provides the earth separately, though this is a recent addition in some countries.

Nothing wrong with that, Civil Engineering is the second oldest Engineering profession in the World, by thousands of years. And a very respectable profession at that. However I must tell you that the Physicist's meaning for observer and onservation and uncertainty (as in the Uncertainty Principle) is not what you understand. An observation is any interaction between some object and the rest of the universe, dead or alive it doesn't matter. So some part of the rest of the universe is the 'observer'. Similarly the Uncertainty Principle has nothing to do with either knowledge or statistics. As a Civ Eng you may be familiar with the statistics of Limit State Theory. The UP is nothing like that. Say an atom in a fluid absorbs a single photon of light passing through. That is an observation of the photon by the atom. The UP in this case appears as a slight smearing of the dark line in the electromagneticspectrum, corresponding to the colour of that photon due to the finite time it takes for the absorbtion to occur.

You should not be using 1.5 mm2 for power wiring in the UK. Power should be at least 2.5mm2. That cable is meant for lighting circuits. It used to be also used for direct spurs off a ring main of less than 2m length, but I think that is now frowned upon.

I don't know if this was aimed at my post but if so it is besides the point. The UK wiring regulations publish the voltage drops in mV/m for electricians to estimate the drop in a supply cable. A value of 31 is provided for 1.5mm2 wire. (BS 7671) https://the-regs.co.uk/blog/?p=481 So say this a 100m cable was supplying an outhouse or a tall building: voltage drop = 21 x 16 x 100 / 1000 Volts = 49.6 volts at 16 amps. So the OP's 200volt supply would be down to a 150 volt supply at the end of that cable ! This could play havoc with many pieces of equipment.

Pity you edited this before I could respond to the original. It is not a good idea to remove the original question. Yes I would expect the current density in a cable designed for much higher voltage to be lower than at the lower voltage. This is simply because the insulation surrounding the conductor will be thicker and therefore also a greater insulator of heat. This does not mean you can increase the current in a higher voltage cable and still meet regulations. I note you application is a 16 amp circuit, which sound domestic to me, with 1.5mm2 conductors. This sounds European. Note that the 1.5mm2 is not the physical cross sectional area of the cable, but an equivalent depending upon the cable type, (stranded, solid etc) as well as the insulation type. This is determined by the manufacturer. Note also that the insulation has to withstand the peak to peak voltage plus a safety factor. This will not be your 200v stated. Another very important factor you should consider, often overlooked by the inexperienced, is the cable length. Particularly as you appear to want to run it near maximum current. In these circumstances the cable sizing is often limited by acceptable voltage drop and therefore lenths, rather than current or voltage per se. At some point you will need to select a larger section to avoid unacceptable voltage drop.

Nice to have the Scots viewpoint. +1

Thank you I will (try to) remember that next time I want 13 squared or 12 squared. They are 31 squared and 21 squared reversed. +1

It's more fun that that because there are yet more pronunciations of 'ro..' as in 'roan', 'Ron', 'roil' and 'royal' All this arises becasue there are many more sounds available than there are letter of the alphabet. We also have route and route, pronounced differently (unlike the Americans)