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John Cuthber

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Posts posted by John Cuthber

  1. 16 minutes ago, leapyear said:

    0.3 micrometers is width a femtosecond can get light to travel. 0.3 is around the size of a virus. We can't get a double slit experiment to show us fringes when using viruses.

    I doubt anyone ever tried. And, since viruses come in a variety of sizes, it's clear that you are talking nonsense.

    In fairness, the OP's question is interesting
    186282 miles, 698 yards, 2 feet, and 5+ 21/127 inches per second

    is a weird number.

  2. On 5/23/2019 at 8:09 AM, Sensei said:


    Typical way C/C++ programmer is using the most basic C language built-in pseudo-random numbers generator is:

    srand( time( NULL ) );
    int value = rand();

    to get value in range in 0....RAND_MAX (0x7fff = 32767)

    Time is input parameter to so called random seed.

    The same seed, the same sequence of numbers returned by rand() function.

    But time (in seconds if returned by time() function) is changing, so each execution output sequence will be different. At least until overflow. srand() takes 32 bit unsigned integer as parameter, so overflow will happen after 2^32 / 60 / 60 / 24 / 365.25 = ~ 136 years (ignoring timezone changes)

    Non-standard pseudo-random number generators typically use current time (better with millisecond/microsecond precision) of machine to initialize random seed (srand()-equivalent function parameter).


    So, if I have two computers running at the same time and they both use this method, they will always generate the same "random" number.
    That seems the very antithesis of randomness.

  3. 42 minutes ago, MigL said:

    Just to be a thorn in your side, John :-p ...

    Personal Income tax was introduced in Canada in the year 1917.
    IIRC our Prime Minister from 1911 to 1920 was Sir R Borden, who was a Conservative until the election of 1917, and subsequently a Unionist ( I seem to remember from High School history class ).
    He not only introduced your criteria for liberalism, but also suffrage for women, in 1918.

    Define "Right" and "Left" and also "Liberal" and "Conservative".

    In this context the original use of Liberal meant those who wanted liberal government spending.
    That may or may not have any correlation with a view on personal liberty on matters such as marriage, suffrage etc.

  4. Setting gun control aside for a minute...
    One important distinction seldom seems to get an airing.

    If you are not personally able to afford all your own healthcare, education, transport and other needs then it makes sense to vote for a government that will help with those things.

    Most people are in that position- they make use of state schools rather than fee-paying ones and so on.

    So most people should vote for a government that provides this sort of assistance.
    The only practical mechanism to do that is by taxing people and, there's no point in taxing people with little or no money- so a progressive tax system of some sort is needed.
    So, most people should vote for a government that taxes the wealthier members of society in order to help those who are less well off.

    And so most people should vote for a more or less Left wing government.

    And, in a democracy, the majority view- a Left leaning government should always be elected.

    The Right wing parties know this. And yet they seek power.

    And, I conclude from this that one trait of Right wing politicians (though not necessarily of Right wing voters) is dishonesty.

    They know they can only get in to power by misleading people into voting against their own personal best interests.

    OK, so far, that's just conjecture.

    Here is some evidence

    It's not exactly a new observation.



  5. 8 hours ago, Moreno said:

    Are you sure in it?!


    On 12/9/2019 at 7:55 PM, John Cuthber said:


    So, if I have got the arithmetic right, the use of the ideal gas equation gives you an answer that's at least ten fold wrong (and I have no direct data about how much worse it actually is).


  6. 7 hours ago, Moreno said:

    So, how strong tank do you need if 700 bar tank will rupture?! 

    We don't know.
    The data we have only goes to 10 KBar, Extrapolating from that it looks like you need more than 20 KBar, but we don't know how much more.

  7. 11 minutes ago, StringJunky said:

    I presume under stp.

    STP seems an odd thing to presume when the conditions are stated to start at 700 bar and go up.


    2 hours ago, Moreno said:

    So, if we will fill a cylinder designed to withstand 700 bar pressure (similar to those in Toyota Mirae) with LNG and will left it unattended and with no further refrigeration, will it explode with time?

    Not if it is properly designed, the bursting disk will fail and vent the tank safely


    However if for some reason that doesn't work (or is not fitted) then yes, the tank will burst- probably violently.

    The release of the methane will lead to it mixing with air.
    Sooner or later it will be diluted down to a flammable mixture.

    It is then a matter of luck if you get a second explosion.


  8. On 12/13/2019 at 7:09 PM, StringJunky said:

    So, over nearly 20 years he's not allowed to evolve his thoughts?

    If it was 20 years since he flip flopped, you would have a point.
    But it isn't,so...


    On 12/13/2019 at 7:09 PM, StringJunky said:

    ...no confidence in Corbyn.

    Tautologically true- since he lost. But unhelpful.

    Why didn't they have any trust in Corbyn?

    He is the most successful leader of the opposition in history. (Having just successfully opposed more government votes than any other).

    He was re-elected  in his own constituency- where they presumably know what he's like.


    Do you think it might be anything to do with this sort of thing?

    On 12/13/2019 at 9:00 PM, MigL said:

    I get the impression people didn't vote in support of Brexit, but in support of ending the instability and indecisiveness of the last three years.
    Basically they were fed up with the whole thing.

    Yes, and somebody sold them the lie that Boris was going to stop the uncertainty. In fact he was the one guaranteed to continue it.
    Brexit will not be over at the end of January- that's just the lie he and his cronies told.


    On 12/13/2019 at 9:58 PM, StringJunky said:

    I've read several times from Labour supporters they are fed up with the issue and that the result of the referendum should be respected.

    At the 2016 referendum roughly two thirds of Labour party voters voted to remain.
    The Leave side cheated in that referendum.
    They should have re-run it.

    If it had been legally binding, there would have been a rerun.  But, because the  outcome was "advisory" they didn't have teh authority to force a repeat- and police it better to stop Leave cheating this time.


    On 12/13/2019 at 9:58 PM, StringJunky said:

    I don't think, in the end, Brexit will be as severe as some people fear.

    OK, that depends on the weasel words "some people".

    It's hard to see how we will avoid the destruction of the NHS for a start. That's presumably worse than most people expected



    On 12/13/2019 at 8:19 PM, StringJunky said:

    Yes. He was evasive.

    You do know which one it was that literally hid in the fridge to avoid reporters, don't you?

    And which one didn't show up at his own hustings...?

    And which one didn't actually appear on the party leaders' debate on climate ?

    And which one refused to be interviewed?

  9. 15 hours ago, Butch said:

    First off, there is no truth

    Are you sure?
    Sorry, couldn't resist it.

    (It's pantomime season)

    More seriously, it's an interesting topic, and it feeds into other areas (which I accept are probably  off-topic)

    Is the belief that the Earth is flat essentially comparable with the idea that some bunch of billionaires have your best interests at heart and you should vote for them?

    One difference is that it doesn't matter to me if you think the Earth's flat (unless you are my pilot) but your vote makes a difference to my life.

    It would, for a number of reasons be very useful to understand  this issue.

    I suspect that the Conservative party did- and that's how the lying guy who hid in the fridge from reporters is now PM.

  10. 18 hours ago, StringJunky said:

    The Irish DUP, who propped the Tories up, aren't happy with the existing agreement but everything else seems arranged with the EU.

    Yes and no.
    There is no agreed plan for the UK leaving the EU- just a date.
    And there is no plan for forming new trade deals with the rest of the world- except the one where Boris sells the NHS to the US drugs companies.

    There's an important aspect to this which seems not to get the coverage it should.

    Boris ran on a single issue ticket "Get brexit done".

    Two thirds or so of the electorate voted against it. [ now the numbers have been published, I'm editing this to say it's about 60% who voted against him]
    And yet he's doing it anyway.

    Our electoral system is badly broken.

  11. 4 minutes ago, StringJunky said:

    Corbyn has been very vague on his position

    He plans to try to negotiate the best deal available, then put it to the public in a referendum.

    Which part of that is vague?

    I grant you "best" is a bit subjective but there's only on real plan on offer and it's the one presented by May and Johnson with marginal changes.


  12. One way to summarise the absurdity of making gold from mercury is to point out that people deliberately did it the other way round.

    They made mercury from gold.

    They wanted a single isotope of mercury (because they wanted to use it in a mercury vapour lamp with a very narrow emission line the other isotopes emit at very slightly different wavelengths.)

    So they got some gold- which only has one stable isotope and irradiated it   to get a single mercury isotope 



    I found some sort of helpful data
    Page 1155 tells me that at 1000 MPa and 290K the density of methane is 571 g/litre

    So, even at ten thousand bar the pressure isn't high enough to raise the density to that of liquid methane at its normal  boiling point.


    So, if I have got the arithmetic right, the use of the ideal gas equation gives you an answer that's at least ten fold wrong (and I have no direct data about how much worse it actually is).

    At half that pressure the density is about 497 so the density doesn't change very fast with pressure. That, in turn suggests that even at 20KBar the density would be less that that of the liquid


  14. 5 hours ago, YJ02 said:

    its really quite easy to find on any search

    here you go, took my about 20 seconds:



    As far as I can tell, none of those is actually valid.

    That's not to say there aren't viable claims to be made; just that the report you cited doesn't show them.

    It's interesting to note that the Left is saying that the impeachment action is in support of justice, rather than their cause.- They may be lying.

    What is the Right's justification for opposing it?

    Do they not want an investigation and hearing that  would clear their guy and make the opposition look stupid?

  15. 20 hours ago, swansont said:


    Better than the one you’ve offered, though.

    Fair point.
    OK imagine I fill a tank with liquid methane at its normal boiling point.

    The density is 0.656 kg/litre

    And if I close the tank and let it warm up then (ignoring the deformation of the tank)  the density will stay the same, so I need to find the pressure where gaseous (strictly, supercritical) methane has that density at room temperature- say 20C or 293K.
    I spent a while trying to find data for that, but I couldn't. I will have a look when I get  back to work, to see if anyone has the data.


    On the other hand, if I use pv=nrt well, p=nrt/v

    I have chosen v= 1 litre

    the mass is 656g 

    That's 41 moles so n = 41

    r = 0.0813 litre bar / k/mol

    About 950 Bar (I think- feel free to check).

    However, fundamentally, the reason I said it was a way of estimating the pressure badly is that you are using the ideal gas laws- which assume that the compressibility of a gasi is quite large. 

    However, you are actually considering a supercritical fluid.

    Gases are easy to compress because they are mainly empty space.

    That's not the case with supercritical fluids where the molecules are nearly "in contact" with one another. If the molecules are "in contact" then you have a liquid

    In the case of liquids, the compressibility is tiny- for most  practical purposes water is regarded as incompressible, for example.


    So, to get the 656 g of supercritical fluid which (near the critical point) has a density of 0.562 kg/l into a 1 litre tank you need to compress it by a factor of about 85%.

    Now, I know it's not the same thing, but to compress water to that extent the pressure needed is huge.

    The compressibility is about 0.5% per 100 Bar

    And you are trying to compress it by about 15%
    That's about 3000 bar.

    Methane is going to be about the same ballpark.

  16. 3 hours ago, dimreepr said:

    He never deliberately hurt anyone.

    Did he ever knock his opponent out?


    5 hours ago, Prometheus said:

    What? Sorry, i just don't know what you're trying to communicate. Maybe someone else who understands your point can try to articulate it in a different way.

    X increases health risk by a. Y increases health risk by b.

    a < b.

    Society will ban something if the health risk >= b. Therefore Y is banned.

    Tell me where intention comes into this equation. 

    In general cutting someone's leg off is banned.

    But removing a gangrenous leg, to save the patient is permitted.


    In both cases, harm is done- the guy loses a leg.
    But in one case the intent (even if the operation fails) is to help them.


    Also, if this"Society will ban something if the health risk >= b. Therefore Y is banned." was right, the drugs policy would be utterly different.




  17. 3 minutes ago, Prometheus said:

    99% of a boxers time is spent outside the ring

    That's relevant if cricketers typically spend the night on the field.

    Are you saying that, because it is premeditated- they trained and practiced to deliberately hurt people- it is somehow better?

    As far as I can tell, that's the opposite of the view taken society (as codified by the courts.)

  18. 1 hour ago, Prometheus said:

    So sometimes consent is valid and sometimes not. What you have still failed to address is why consent in boxing is not valid, and consent in rugby, say, is.

    Because, though you repeatedly fail to accept it, there is a difference.

    You do not set out to brain damage your opponent when you play Rugby.

    Do you accept that there is a fundamental difference between boxing and other sports?

    I can only presume that you don't understand the difference.

    The difference is that of intent.

    Like the other difference you don't seem to understand- that between pharmacology and murder.

    Giving people physiologically  active chemicals  might be homicidal, or it may be medical.

    The difference rests solely on why you do it.

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