SI units and QED [Archive]

Mike Helland

Sep12-04, 02:24 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Hello,\n\nAccording to the book QED, the theory by the same name can explain\nlight, heat, and electric phenomena.\n\nThere are three SI base units that relate to these phenomena, measure\nof intensity, measure of temperature, and measure of electric current.\n\nI might be mistaken but I think that intensity is how many photons are\nreceived within a given time period, temperature is how fast the\nelectrons of a substance are moving, and current is how many electrons\nare moving down a some conducter.\n\nIs it true that the three SI base units in question may be understood\nin terms of the movement of particles? In other words, can those three\nunits be described in terms of the other base units?\n\nFor example:\n\nif N photons are received in S seconds, the intensity is I cd\n\nif the electrons are moving at a V m/s the temperature of the\nsubstance is equal to T kelvin\n\nif N electrons pass through a conductor in S seconds there are X amps\n\nAre there any formulas for these conversions?\n\nI\'m asking out of pure curiousity. I don\'t think that there are any\nreal practical uses for these formulas, or for reducing the number of\nSI base units. Are there?\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Hello,

According to the book QED, the theory by the same name can explain
light, heat, and electric phenomena.

There are three SI base units that relate to these phenomena, measure
of intensity, measure of temperature, and measure of electric current.

I might be mistaken but I think that intensity is how many photons are
received within a given time period, temperature is how fast the
electrons of a substance are moving, and current is how many electrons
are moving down a some conducter.

Is it true that the three SI base units in question may be understood
in terms of the movement of particles? In other words, can those three
units be described in terms of the other base units?

For example:

if N photons are received in S seconds, the intensity is I cd

if the electrons are moving at a V m/s the temperature of the
substance is equal to T kelvin

if N electrons pass through a conductor in S seconds there are X amps

Are there any formulas for these conversions?

I'm asking out of pure curiousity. I don't think that there are any
real practical uses for these formulas, or for reducing the number of
SI base units. Are there?

Old Man

Sep13-04, 03:17 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>"Mike Helland" <mobydikc@gmail.com> wrote in message news:11990c07.0409101017.2d2c1523@posting.google.c om...\n> Hello,\n>\n> According to the book QED, the theory by the same name can explain\n> light, heat, and electric phenomena.\n>\n> There are three SI base units that relate to these phenomena, measure\n> of intensity, measure of temperature, and measure of electric current.\n>\n> I might be mistaken but I think that intensity is how many photons are\n> received within a given time period, temperature is how fast the\n> electrons of a substance are moving, and current is how many electrons\n> are moving down a some conducter.\n>\n> Is it true that the three SI base units in question may be understood\n> in terms of the movement of particles? In other words, can those three\n> units be described in terms of the other base units?\n>\n> For example:\n>\n> if N photons are received in S seconds, the intensity is I cd\n>\n> if the electrons are moving at a V m/s the temperature of the\n> substance is equal to T kelvin\n>\n> if N electrons pass through a conductor in S seconds there are X amps\n>\n> Are there any formulas for these conversions?\n>\n> I\'m asking out of pure curiousity. I don\'t think that there are any\n> real practical uses for these formulas, or for reducing the number of\n> SI base units. Are there?\n\nThe distribution of molecular velocities, v, in a gas of temperature, T,\nis given by a Maxwrll\'s distribution:\n\nn(v) / n_0 = exp [- m v^2 / 2 k T ]\n\nor approximately,\n\n(1 / 2) m (v_ave)^2 ~ (3 / 2) k T\n\nwhere k is Bolltzmann\'s constant.\n\nThe Stefan-Boltzmann law relates luminous intensity to temperature for\nblack-body radiation. Radiation energy flux (W / m^2)\n\nP / A = w_b *T^4\n\nWhere w_b can be expressed in terms of fundamental physical constants,\nh , c, and k.\n\nElectric current and elementary charge are related to molecular mass via\nprecise electroplating experiments (Avogadro\'s Number).\n\n[Old Man]\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>"Mike Helland" <mobydikc@gmail.com> wrote in message news:11990c07.0409101017.2d2c1523@posting.google.c om...
> Hello,
>
> According to the book QED, the theory by the same name can explain
> light, heat, and electric phenomena.
>
> There are three SI base units that relate to these phenomena, measure
> of intensity, measure of temperature, and measure of electric current.
>
> I might be mistaken but I think that intensity is how many photons are
> received within a given time period, temperature is how fast the
> electrons of a substance are moving, and current is how many electrons
> are moving down a some conducter.
>
> Is it true that the three SI base units in question may be understood
> in terms of the movement of particles? In other words, can those three
> units be described in terms of the other base units?
>
> For example:
>
> if N photons are received in S seconds, the intensity is I cd
>
> if the electrons are moving at a V m/s the temperature of the
> substance is equal to T kelvin
>
> if N electrons pass through a conductor in S seconds there are X amps
>
> Are there any formulas for these conversions?
>
> I'm asking out of pure curiousity. I don't think that there are any
> real practical uses for these formulas, or for reducing the number of
> SI base units. Are there?

The distribution of molecular velocities, v, in a gas of temperature, T,
is given by a Maxwrll's distribution:

n(v) / n_0 = \exp [- m v^2 / 2 k T ]

or approximately,

(1 / 2) m (v_{ave})^2 ~ (3 / 2) k T

where k is Bolltzmann's constant.

The Stefan-Boltzmann law relates luminous intensity to temperature for
black-body radiation. Radiation energy flux (W / m^2)P / A = w_b *T^4

Where w_b can be expressed in terms of fundamental physical constants,
h , c, and k.

Electric current and elementary charge are related to molecular mass via
precise electroplating experiments (Avogadro's Number).

[Old Man]

Bjoern Feuerbacher

Sep14-04, 12:11 PM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nMike Helland wrote:\n> Hello,\n>\n> According to the book QED,\n\nBy whom? There are several books with that title.\n\n\n> the theory by the same name can explain\n> light, heat, and electric phenomena.\n\nHeat? I doubt that.\n\n\n> There are three SI base units that relate to these phenomena, measure\n> of intensity, measure of temperature, and measure of electric current.\n>\n> I might be mistaken but I think that intensity is how many photons are\n> received within a given time period, temperature is how fast the\n> electrons of a substance are moving, and current is how many electrons\n> are moving down a some conducter.\n\nThat is vaguely right.\n\n\n\n> Is it true that the three SI base units in question may be understood\n> in terms of the movement of particles?\n\nThey *can* measure the movement of particles, but they don\'t always do.\n\n\n> In other words, can those three\n> units be described in terms of the other base units?\n\nThey can, but not as you think.\n\n\n> For example:\n>\n> if N photons are received in S seconds, the intensity is I cd\n\nNo, it is not so simple.\n\n\n\n> if the electrons are moving at a V m/s the temperature of the\n> substance is equal to T kelvin\n\nNo, it is not so simple.\n\n\n\n> if N electrons pass through a conductor in S seconds there are X amps\n\nWell, finally, that does indeed work.\n\n\n\n> Are there any formulas for these conversions?\n\nFor the last one: simply read up the relation between charge and\ncurrent, and the charge of an electron. You should be able to get\nthe relationship then quite easily.\n\n\n> I\'m asking out of pure curiousity. I don\'t think that there are any\n> real practical uses for these formulas, or for reducing the number of\n> SI base units. Are there?\n\nSince there are other unit systems which have *less* basic units than\nthe SI, obviously there *are* practical uses for relationships between\ndifferent units.\n\n\nBye,\nBjoern\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Mike Helland wrote:
> Hello,
>
> According to the book QED,

By whom? There are several books with that title.

> the theory by the same name can explain
> light, heat, and electric phenomena.

Heat? I doubt that.

> There are three SI base units that relate to these phenomena, measure
> of intensity, measure of temperature, and measure of electric current.
>
> I might be mistaken but I think that intensity is how many photons are
> received within a given time period, temperature is how fast the
> electrons of a substance are moving, and current is how many electrons
> are moving down a some conducter.

That is vaguely right.

> Is it true that the three SI base units in question may be understood
> in terms of the movement of particles?

They *can* measure the movement of particles, but they don't always do.

> In other words, can those three
> units be described in terms of the other base units?

They can, but not as you think.

> For example:
>
> if N photons are received in S seconds, the intensity is I cd

No, it is not so simple.

> if the electrons are moving at a V m/s the temperature of the
> substance is equal to T kelvin

No, it is not so simple.

> if N electrons pass through a conductor in S seconds there are X amps

Well, finally, that does indeed work.

> Are there any formulas for these conversions?

For the last one: simply read up the relation between charge and
current, and the charge of an electron. You should be able to get
the relationship then quite easily.

> I'm asking out of pure curiousity. I don't think that there are any
> real practical uses for these formulas, or for reducing the number of
> SI base units. Are there?

Since there are other unit systems which have *less* basic units than
the SI, obviously there *are* practical uses for relationships between
different units.

Bye,
Bjoern

J. J. Lodder

Sep16-04, 07:09 AM

<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Mike Helland <mobydikc@gmail.com> wrote:\n\n> According to the book QED, the theory by the same name can explain\n> light, heat, and electric phenomena.\n\nSure, QED is the \'theory of everything\',\nwhen you restrict yourself to purely electromagnetic phenomena,\nwhich in practice is almost everything in everyday life.\nDon\'t expect to understand the engine of your car with it though.\n\n> There are three SI base units that relate to these phenomena, measure\n> of intensity, measure of temperature, and measure of electric current.\n>\n> I might be mistaken but I think that intensity is how many photons are\n> received within a given time period, temperature is how fast the\n> electrons of a substance are moving, and current is how many electrons\n> are moving down a some conducter.\n\nIf \'electrons\' here means \'free electrons\'.\n\n> Is it true that the three SI base units in question may be understood\n> in terms of the movement of particles? In other words, can those three\n> units be described in terms of the other base units?\n>\n> For example:\n>\n> if N photons are received in S seconds, the intensity is I cd\n>\n> if the electrons are moving at a V m/s the temperature of the\n> substance is equal to T kelvin\n>\n> if N electrons pass through a conductor in S seconds there are X amps\n>\n> Are there any formulas for these conversions?\n\nOf course. Look them up in any table of fundamental constants.\nYou should understand though that how many \'basic\' units there are\nis first of all a question of practicality.\nWhat matters to a metrologist\nis how accurately a given unit can be reproduced,\nnot how nicely it is defined.\n\nThus we have a separate unit for temperature\nbecause it is not practical to realize a temperature unit\nbased on how many joules of kinetic energy an electron has. (on average)\n\nThere are proposals though to redefine the Ampere\nas a current of how (defined number) many electrons/second.\nThis may come about eventually,\nwhen the needed technology will be there,\nand supposing some other method (like defining Avogadro)\nwill not be more accurate still.\n\nBest,\n\nJan\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form">  View this Usenet post in original ASCII form </a></div><P></jabberwocky>Mike Helland <mobydikc@gmail.com> wrote:

> According to the book QED, the theory by the same name can explain
> light, heat, and electric phenomena.

Sure, QED is the 'theory of everything',
when you restrict yourself to purely electromagnetic phenomena,
which in practice is almost everything in everyday life.
Don't expect to understand the engine of your car with it though.

> There are three SI base units that relate to these phenomena, measure
> of intensity, measure of temperature, and measure of electric current.
>
> I might be mistaken but I think that intensity is how many photons are
> received within a given time period, temperature is how fast the
> electrons of a substance are moving, and current is how many electrons
> are moving down a some conducter.

If 'electrons' here means 'free electrons'.

> Is it true that the three SI base units in question may be understood
> in terms of the movement of particles? In other words, can those three
> units be described in terms of the other base units?
>
> For example:
>
> if N photons are received in S seconds, the intensity is I cd
>
> if the electrons are moving at a V m/s the temperature of the
> substance is equal to T kelvin
>
> if N electrons pass through a conductor in S seconds there are X amps
>
> Are there any formulas for these conversions?

Of course. Look them up in any table of fundamental constants.
You should understand though that how many 'basic' units there are
is first of all a question of practicality.
What matters to a metrologist
is how accurately a given unit can be reproduced,
not how nicely it is defined.

Thus we have a separate unit for temperature
because it is not practical to realize a temperature unit
based on how many joules of kinetic energy an electron has. (on average)

There are proposals though to redefine the Ampere
as a current of how (defined number) many electrons/second.
This may come about eventually,
when the needed technology will be there,
and supposing some other method (like defining Avogadro)
will not be more accurate still.

Best,

Jan