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| Benj... |
 Posted: Fri Oct 30, 2009 6:41 am |
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Guest
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Consider the Feynman Paradox reworked slightly as follows.
Start with two superconducting loops of current forming a Helmholtz
coil set. Then put an insulating loop that can rotate freely at the
center. Charge the loop giving a certain charge density.
We know that if the current in the coils is stopped (say heated and
drop out of superconductivity) that an E field will be produced that
accelerates the charged ring. All this stuff is calculable.
Now to make a "paradox" Feynman asserts that since the coils are not
moving there is no angular momentum before we start and since the
charged ring ends up rotating there is angular momentum after we stop
the current, hence conservation of angular momentum is violated.
But obviously Feynman is wrong about no angular momentum before we
start. There is a current going round and round the coils! Now some
say that the angular momentum due to the current is actually stored in
the field. But we know it takes crossed E and B fields to produce
momentum. Some have explained the Paradox by pointing out that the
charges plus the magnetic field represents crossed fields hence
momentum. But this seems wrong since there should be angular momentum
present from a circulating current even before the charged ring is
inserted. Which means no crossed fields to produce it.
So the question then is just how do we calculate the angular momentum
contained in a current circulating in a wire loop? It appears it can't
just be due to the orbits of the electrons in the wire around the
loops. We know it's value as we can calculate the angular momentum in
the ring after the current stops. And that must be equal to the
momentum due to the original current in the wire. |
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| DanB... |
| Posted: Fri Oct 30, 2009 12:45 pm |
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Guest
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Benj wrote:
[quote]
Now to make a "paradox" Feynman asserts that since the coils are not
moving there is no angular momentum before we start and since the
charged ring ends up rotating there is angular momentum after we stop
the current, hence conservation of angular momentum is violated.
[/quote]
This is just like saying that when I pull a string on a toy gyro I am
creating angular momentum that did not exist before the pull. Which, of
course, is not true. |
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| Benj... |
| Posted: Fri Oct 30, 2009 6:12 pm |
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Guest
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On Oct 30, 1:45 pm, DanB <a... at (no spam) some.net> wrote:
[quote]Benj wrote:
Now to make a "paradox" Feynman asserts that since the coils are not
moving there is no angular momentum before we start and since the
charged ring ends up rotating there is angular momentum after we stop
the current, hence conservation of angular momentum is violated.
This is just like saying that when I pull a string on a toy gyro I am
creating angular momentum that did not exist before the pull. Which, of
course, is not true.
[/quote]
Interesting. But let's make the system more isolated so we aren't
bringing in forces from outside. Say you have a wound-up spring that
you bring down to the top, hook it on, and trigger it. Now if you
didn't hold on to the spring mechanism it would spin one way and the
top the other such that the total angular momentum of the system is
still zero. However, if we hold onto the spring mechanism the top
spins up and has angular momentum aftereward, but there was none
before we started. Now we applied a force to the spring box to keep it
from turning, but it wasn't allowed to turn. So that means that since
V = 0 there actually was not angular momentum to the spring box as
there is in the case when it is allowed to spin freely.
So this seems to imply that that the magnetic field is somehow like
the spring, and for this thing to work, there must be a reaction force
upon the coils trying to make them spin in the opposite direction!
What would cause such a force? |
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| iman way... |
| Posted: Sat Oct 31, 2009 9:30 am |
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Guest
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On 31 أكتوبر, 11:12, Benj <bjac... at (no spam) iwaynet.net> wrote:
[quote]On Oct 30, 1:45Â pm, DanB <a... at (no spam) some.net> wrote:
Benj wrote:
Now to make a "paradox" Feynman asserts that since the coils are not
moving there is no angular momentum before we start and since the
charged ring ends up rotating there is angular momentum after we stop
the current, hence conservation of angular momentum is violated.
This is just like saying that when I pull a string on a toy gyro I am
creating angular momentum that did not exist before the pull. Which, of
course, is not true.
Interesting. But let's make the system more isolated so we aren't
bringing in forces from outside. Say you have a wound-up spring that
you bring down to the top, hook it on, and trigger it. Now if you
didn't hold on to the spring mechanism it would spin one way and the
top the other such that the total angular momentum of the system is
still zero. However, if we hold onto the spring mechanism the top
spins up and has angular momentum aftereward, but there was none
before we started. Now we applied a force to the spring box to keep it
from turning, but it wasn't allowed to turn. So that means that since
V = 0 there actually was not angular momentum to the spring box as
there is in the case when it is allowed to spin freely.
So this seems to imply that that the magnetic field is somehow like
the spring, and for this thing to work, there must be a reaction force
upon the coils trying to make them spin in the opposite direction!
What would cause such a force?
I know that, my article may be unusual ,but it might be useful. PLEASE[/quote]
read it
WHAT IS ISLAM
Islam is composed of three main areas: Utterance (to testify that
there is no god worthy of worship except Allah and that Muhammad is
His slave and messenger), faith, and deeds.
Faith is to believe in Allah, the Angels, the Heavenly Scriptures,
Prophets, the last Day, and in the ability of Allah to will the
existence of good or bad.
Deeds are: Salat (Prayers,) Zakat (a certain fixed proportion of the
wealth – liable to Zakat – of a Muslim to be paid yearly for the
benefit of the poor,) Siyam (Fasting,) and Hajj (Pilgrimage.)
Faith in Allah
1. We believe that Allah is one God, our Lord and the Lord of
everything, and the Creator of everything.
2. All other than Him are created, and are servants who share nothing
with Allah. Even Angels and Prophets are merely created servants
submitting to Allah.
3. Among them are Jesus and Muhammad (Peace be upon them); both have
no trace of deity (godhood).
4. Allah is the Living Self-Subsisting, Eternal, the First without a
beginning and the Last without an end.
5. He hears everything and sees everything.
6. He is Most Gracious, Most Merciful, All-Dominating and He has the
Most Beautiful Names and the Noblest Attributes.
7. He has created us out of nothing, and made us in the best form and
He has given us all graces and bounties.
8. Hence we are not permitted to worship or submit to any other than
Him, whether a favorite Angel or a chosen Prophet.
9. Whoever directs his prayers, bows or prostrates (in worship), or
offers sacrifice to any other than Allah, he is an infidel and not a
Muslim even if he declares that he is a Muslim. Allah says: "Say:
Truly, my prayer and my service of sacrifice, my living and my dying
are (all) for Allah, the Cherisher of the Worlds. No partner has He.
And of this I have been commanded and I am the first of those who
submit to His Will." (Holy Qur’an; 6:162-163)
10. Islam is the religion of Monotheism: it denies the Dualism of
Magians and the Trinity of Christians. Islam teaches that Allah is One
and only One. No one shares with Him, His Dominion or His Command. He
has the Most Beautiful Names and the Noblest Attributes. Allah says:
"Say! He is Allah, the One. He is The Most Unique, The Eternal, The
Absolute. He begets not, nor was He begotten. And there is none like
unto Him." (Holy Qur’an; 112)
Faith in Angels
1. Allah has created Angels to worship Him, to carry out His commands
and to be His messengers to His Prophets.
2. One of the angels is Gabriel who used to bring down Revelation to
our Prophet Muhammad (PBUH).
3. Another Angel is Michael who is in charge of rain falling.
4. A third one is the "Angel of Death" who is in charge of taking the
souls of people whose death is due.
5. Angels are but servants honored by Allah.
6. Hence we honor them and speak of them respectfully.
7. But we worship none of them, nor do we take them as Allah’s sons or
daughters (as infidels claim).
8. We worship only Allah who created them in this wonderful kind of
creation.
Allah (Glory be to Him) says: "And they say: The Most Gracious has
begotten a son, Glory be to Him! They are but honored servants. They
do not speak before He speaks, and they act (in all things) by His
command. He knows what is before them, and what is behind them, and
they offer no intercession except for those whom He accepted, and they
stand in awe for the fear of Him. If any of them should say, ‘I am a
God besides Him’, such one We should reward with Hell. Thus do We
reward those who do wrong." (Holy Qur’an; 21:26-29)
Faith in Holy Scriptures
1. Allah has sent down to a number of Messengers, Books in order to
proclaim them to mankind. These Books contain the Words of Allah.
2. Among them are the Sheets of Ibrahim (Abraham,) Taurat revealed to
Musa (Moses,) Az-Zabour (Psalms) revealed to Dawud (David,) The Injil
(Gospel) revealed to Isa (Jesus,) and the Qur’an sent down to Muhammad
(Peace be upon them all).
3. Jews and Christians distorted some parts of their Books (Taurat and
Injil).
4. Being the last Book assuredly guarded from corruption, the Qur’an
confirms the truth in the previous Books and guards it.
5. Whatever, in those Books, differs from the Qur’an is corrupted or
abrogated. Allah (Glory be to Him) says: "And We have sent down to you
the Book (this Qur’an) in truth, confirming the scripture that came
before it, and guarding it…" (Holy Qur’an; 5:48)
6. Allah revealed the Qur’an in Arabic and has firmly promised to
protect it. His last Message is free from all corruption; He, Most
High, says about the Qur’an: "We have, without doubt, sent down the
Message, and We will assuredly guard it (from corruption)" ( Holy
Qur’an; 15:9)
Faith in Prophets
1. We believe that Allah chose from among mankind some Prophets to
deliver His Guidance. From among those Prophets He selected Some
Messengers.
2. He sent to the Messengers Laws and commanded them to proclaim these
laws and to clarify them to their people.
3. Some of the great Messengers of Allah were Nooh (Noah,) Ibrahim
(Abraham,) Musa (Moses), Isa (Jesus,) and Muhammad (peace be upon them
all).
4. Embracing Islam does not mean to disbelieve in Moosa, Isa, or any
other Prophet.
5. Islam teaches you how to believe correctly in all Prophets.
Allah (Glory be to Him) says in the Qur’an: "And We have sent down to
you the Book (this Qur’an) in truth, confirming the scripture that
came before it, and guarding it (clarifying the truth they distorted)
…" (Holy Qur’an; 5:48)
6. Allah mentioned the names of a number of Prophets, He, Most High,
says: "Say you (Muslims): We believe in Allah, and the revelation
given to us and to Ibrahim, lsma’il, Isaac, Ya’qoob (Jacob) and the
Tribes, and that which was given to Moosa (Moses), and Isa (Jesus),
and that which was given to all Prophets from their Lord. We make no
difference between one and another of them, and we submit to Allah (in
Islam)." (Holy Qur’an; 2:136)
7. The first Prophet was Adam, father of mankind (PBUH).
8. Muhammad, the Prophet of Islam (PBUH) is the seal (the last) of the
Prophets. No Prophet is to come after him up to the end of this world.
9. Hence the fact that Islam is the only true religion to remain up to
the Last Day.
10. He is Muhammad son of Abdullah son of Abdul-Muttalib. He is an
Arab from (the famous tribe) of The Quraysh, a descendant of Ibrahim
(Abraham) and Isma’il (Ishmael) (peace be upon them all).
11. He was born in Makkah (Mecca) in 571 AD (Known as the Year of the
Elephant).
12. Allah sent Revelation to him when he was 40 years old.
13. He stayed in Makkah 13 years calling people to (believe in) Allah.
Only a limited number of people believed in him.
14. After that he emigrated to Al-Madinah and invited its people to
believe in Allah, they accepted.
15. He established the Islamic state, and in the year 8 AH (After
Hijrah) He died at the age of 63 after the whole of the Qur’an was
revealed, and all Arabs embraced Islam.
Faith in the Last Day
1. We believe that there will be another life after this life.
2. When the determined term of this life comes to an end, Allah will
command an Angel to sound the Trumpet and all mankind and all other
creatures will die.
3. Then he (Angel) will sound it again, when, behold, all dead since
Adam will stand out of their graves.
4. Then, Allah will gather all people to account them for what they
did.
5. Those who believed (in Allah), accepted the Messengers (as
truthful) and did good deeds (commanded by Allah), Allah will put them
in Paradise. In Paradise, they will enjoy eternal Bliss.
6. But those who rejected the Messengers and disobeyed Allah’s
commands will be put in Hell. In Hell Fire, they will be in continuous
eternal punishment.
Allah (Glory be to Him) says: "As for him who had transgressed all
bounds, and preferred the life of this world his abode will be Hell-
Fire. And for him who feared of standing in front of his Lord’s
(Tribunal), and restrained (his) soul from lower desires, his abode
will be Paradise." (Holy Qur’an, 79:37-41)
Faith in Fate and Divine Decree
1. We believe in the timeless knowledge of Allah and in His power to
plan and execute His plans and nothing could happen in His Kingdom
against His will.
2. His knowledge and power are in action and command at all times over
His creation.
3. He is Wise and Merciful and whatever He does must have a meaningful
purpose.
4. If this is established in our minds and hearts, we should accept
with good faith all that He does, although we may fail to understand
it fully, or think it is bad.
———–
For more information about Islam
http://english.islamway.com/
http://www.islamhouse.com/
http://www.discoverislam.com/
http://www.islambasics.com/index.php
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Contact Us At
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| Androcles... |
| Posted: Sat Oct 31, 2009 1:47 pm |
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Guest
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"iman way" <imanway555 at (no spam) gmail.com> wrote in message
news:76dedd69-83cd-4425-be87-1fc5924b934d at (no spam) w19g2000yqk.googlegroups.com...
On 31 ??????, 11:12, Benj <bjac... at (no spam) iwaynet.net> wrote:
[quote]On Oct 30, 1:45 pm, DanB <a... at (no spam) some.net> wrote:
Benj wrote:
Now to make a "paradox" Feynman asserts that since the coils are not
moving there is no angular momentum before we start and since the
charged ring ends up rotating there is angular momentum after we stop
the current, hence conservation of angular momentum is violated.
This is just like saying that when I pull a string on a toy gyro I am
creating angular momentum that did not exist before the pull. Which, of
course, is not true.
Interesting. But let's make the system more isolated so we aren't
bringing in forces from outside. Say you have a wound-up spring that
you bring down to the top, hook it on, and trigger it. Now if you
didn't hold on to the spring mechanism it would spin one way and the
top the other such that the total angular momentum of the system is
still zero. However, if we hold onto the spring mechanism the top
spins up and has angular momentum aftereward, but there was none
before we started. Now we applied a force to the spring box to keep it
from turning, but it wasn't allowed to turn. So that means that since
V = 0 there actually was not angular momentum to the spring box as
there is in the case when it is allowed to spin freely.
So this seems to imply that that the magnetic field is somehow like
the spring, and for this thing to work, there must be a reaction force
upon the coils trying to make them spin in the opposite direction!
What would cause such a force?
I know that, my article may be unusual ,but it might be useful. PLEASE[/quote]
read it
WHAT IS ISLAM
==================================================
Listen, fuckwit!
These newsgroups are NOT for religion, whether Xtian, Moslem, Buddhist or
fucking
Easter Bunny. Take your crap and shove it up your arse, you are not welcome
here.
*plonk*
Do not reply to this generic message, it was automatically generated;
you have been kill-filed, either for being boringly stupid, repetitive,
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subjects to a sci. newsgroup, attempting cheapskate free advertising
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or permutation of the aforementioned reasons; any reply will go unread.
Boringly stupid is the most common cause of kill-filing, but because
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as I would any chicken with two heads, either one of which enables the
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This should not trouble you, many of those plonked find it a blessing
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I'm fully aware that you may be so stupid as to reply, but the purpose
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I hope you find this explanation is satisfactory but even if you don't,
damnly my frank, I don't give a dear. Have a nice day and fuck off. |
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| George Herold... |
| Posted: Sat Oct 31, 2009 5:47 pm |
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Guest
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On Oct 30, 12:41 pm, Benj <bjac... at (no spam) iwaynet.net> wrote:
[quote]Consider the Feynman Paradox reworked slightly as follows.
Start with two superconducting loops of current forming a Helmholtz
coil set. Then put an insulating loop that can rotate freely at the
center. Charge the loop giving a certain charge density.
We know that if the current in the coils is stopped (say heated and
drop out of superconductivity) that an E field will be produced that
accelerates the charged ring. All this stuff is calculable.
Now to make a "paradox" Feynman asserts that since the coils are not
moving there is no angular momentum before we start and since the
charged ring ends up rotating there is angular momentum after we stop
the current, hence conservation of angular momentum is violated.
But obviously Feynman is wrong about no angular momentum before we
start. There is a current going round and round the coils! Now some
say that the angular momentum due to the current is actually stored in
the field. But we know it takes crossed E and B fields to produce
momentum. Some have explained the Paradox by pointing out that the
charges plus the magnetic field represents crossed fields hence
momentum. But this seems wrong since there should be angular momentum
present from a circulating current even before the charged ring is
inserted. Which means no crossed fields to produce it.
So the question then is just how do we calculate the angular momentum
contained in a current circulating in a wire loop? It appears it can't
just be due to the orbits of the electrons in the wire around the
loops. We know it's value as we can calculate the angular momentum in
the ring after the current stops. And that must be equal to the
momentum due to the original current in the wire.
[/quote]
Benj, There's no real paradox. The angular momentum is carried in
the E-M fields. I'm not sure exactly how to calculate it, but if you
have the Feynman lectures I'm sure it's in there.
George H. |
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| Benj... |
| Posted: Sat Oct 31, 2009 8:59 pm |
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Guest
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On Oct 31, 10:47 pm, George Herold <ggher... at (no spam) gmail.com> wrote:
[quote]Benj, There's no real paradox. The angular momentum is carried in
the E-M fields. I'm not sure exactly how to calculate it, but if you
have the Feynman lectures I'm sure it's in there.
[/quote]
I"m sure there's no paradox. Feynman implies there is an answer.
However, he says that "We should warn you that the solution in not
easy, nor is it a trick. When you figure it out, you will have
discovered an important principle of electromagnetism."
Now if you search the internet on this question you find all manner of
wild calculations. People have done papers on the subject yet nobody
has actually answered the question. Just what "important principle" is
he talking about? Solutions range from angular momentum present in a
static electric field to the angular momentum present in "crossed" E
and M fields. None of this seems to be what Feynman was talking about.
So it seems that Feynman has stumped the entire physics community
including all the professionals, professors, and theoreticians. No one
else seems to get it either. That that it is any surprise that Feynman
was capable of doing this!
So if it's in the book, It's apparently buried pretty deep! My
thinking goes like this: First off the electric field that rotates the
charge is NOT caused by the magnetic field of the coils! The magnetic
field is totally superfluous. The causality is between the current in
the coils and the E field at the hoop. The angular momentum of the
final motion is easy to see given the rotation and mas of the hoop,
but what and how is the angular momentum of the current in the coils.
The coils are still so they have no MECHANICAL momentum. Thus the only
possibility is for the original angular momentum to be due to motion
of the charges constituting a current and possibly the energy stored
in the magnetic field due to those circulating charges. Whether or not
the magnetic field actually contains angular momentum is not clear,
however, since the energy contained there does keep the charges
circulating longer than they would without that extra energy it is not
a stretch to imagine that this energy goes into extra current (charge
circulation) which in turn translates to extra angular momentum.
It's all not very simple. |
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| Justintruth... |
| Posted: Sat Oct 31, 2009 11:57 pm |
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Guest
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On Nov 1, 1:59 am, Benj <bjac... at (no spam) iwaynet.net> wrote:
[quote]On Oct 31, 10:47 pm, George Herold <ggher... at (no spam) gmail.com> wrote:
Benj, There's no real paradox. The angular momentum is carried in
the E-M fields. I'm not sure exactly how to calculate it, but if you
have the Feynman lectures I'm sure it's in there.
I"m sure there's no paradox. Feynman implies there is an answer.
However, he says that "We should warn you that the solution in not
easy, nor is it a trick. When you figure it out, you will have
discovered an important principle of electromagnetism."
Now if you search the internet on this question you find all manner of
wild calculations. People have done papers on the subject yet nobody
has actually answered the question. Just what "important principle" is
he talking about? Solutions range from angular momentum present in a
static electric field to the angular momentum present in "crossed" E
and M fields. None of this seems to be what Feynman was talking about.
So it seems that Feynman has stumped the entire physics community
including all the professionals, professors, and theoreticians. No one
else seems to get it either. That that it is any surprise that Feynman
was capable of doing this!
So if it's in the book, It's apparently buried pretty deep! My
thinking goes like this: First off the electric field that rotates the
charge is NOT caused by the magnetic field of the coils! The magnetic
field is totally superfluous. The causality is between the current in
the coils and the E field at the hoop. The angular momentum of the
final motion is easy to see given the rotation and mas of the hoop,
but what and how is the angular momentum of the current in the coils.
The coils are still so they have no MECHANICAL momentum. Thus the only
possibility is for the original angular momentum to be due to motion
of the charges constituting a current and possibly the energy stored
in the magnetic field due to those circulating charges. Whether or not
the magnetic field actually contains angular momentum is not clear,
however, since the energy contained there does keep the charges
circulating longer than they would without that extra energy it is not
a stretch to imagine that this energy goes into extra current (charge
circulation) which in turn translates to extra angular momentum.
It's all not very simple.
[/quote]
I'm confused. If there is current traveling in a circular wire there
must be angular momentum because the charges in the wire are moving.
Can you not just take the rxmv of the electrons? |
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| zzbunker at (no spam) netscape.net... |
| Posted: Sun Nov 01, 2009 2:58 am |
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Guest
|
On Oct 30, 11:41 am, Benj <bjac... at (no spam) iwaynet.net> wrote:
[quote]Consider the Feynman Paradox reworked slightly as follows.
Start with two superconducting loops of current forming a Helmholtz
coil set. Then put an insulating loop that can rotate freely at the
center. Charge the loop giving a certain charge density.
[/quote]
Well, half of the Feymann isn't really a paradox.
Since the people who understand electricty invented
lasers, rather than magentic fields, and invented fiber optics, and
reverse compilers
rather than insulators, and invented optical computers,
rather than universities, and invented GPS, Atomic Clock
Wristwatches,
HDTV, 4D Holographics, and Self-Replicating Machines, rather than
superconducting anything.
[quote]
We know that if the current in the coils is stopped (say heated and
drop out of superconductivity) that an E field will be produced that
accelerates the charged ring. All this stuff is calculable.
Now to make a "paradox" Feynman asserts that since the coils are not
moving there is no angular momentum before we start and since the
charged ring ends up rotating there is angular momentum after we stop
the current, hence conservation of angular momentum is violated.
But obviously Feynman is wrong about no angular momentum before we
start. There is a current going round and round the coils! Now some
say that the angular momentum due to the current is actually stored in
the field. But we know it takes crossed E and B fields to produce
momentum. Some have explained the Paradox by pointing out that the
charges plus the magnetic field represents crossed fields hence
momentum. But this seems wrong since there should be angular momentum
present from a circulating current even before the charged ring is
inserted. Which means no crossed fields to produce it.
So the question then is just how do we calculate the angular momentum
contained in a current circulating in a wire loop? It appears it can't
just be due to the orbits of the electrons in the wire around the
loops. We know it's value as we can calculate the angular momentum in
the ring after the current stops. And that must be equal to the
momentum due to the original current in the wire.[/quote] |
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| Y.Porat... |
| Posted: Sun Nov 01, 2009 7:00 am |
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Guest
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On Oct 30, 8:45 pm, DanB <a... at (no spam) some.net> wrote:
[quote]Benj wrote:
Now to make a "paradox" Feynman asserts that since the coils are not
moving there is no angular momentum before we start and since the
charged ring ends up rotating there is angular momentum after we stop
the current, hence conservation of angular momentum is violated.
This is just like saying that when I pull a string on a toy gyro I am
creating angular momentum that did not exist before the pull. Which, of
course, is not true.
[/quote]
------------------------
take a hose of water that is curved
and twisting and push water in it
you get the same problem
and a similar phenomenon
2
get a similar problem in the fibers that
conduct light
those fibers can have any longitudical shape
Y.P
------------------------ |
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| Benj... |
| Posted: Sun Nov 01, 2009 7:28 am |
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On Nov 1, 4:57 am, Justintruth <truth.jus... at (no spam) gmail.com> wrote:
[quote]It's all not very simple.
I'm confused. If there is current traveling in a circular wire there
must be angular momentum because the charges in the wire are moving.
Can you not just take the rxmv of the electrons?
[/quote]
Apparently not. People online have done that and say it's not enough
momentum. And that makes sense because the amount of energy (inertia)
stored by moving electricity depends upon the shape of the wire
(hose). The kinetic energy inertia of water in a hose does not depend
upon the shape of the hose. The energy stored by electricity in a wire
(inductance) does. [Maxwell noted this] So I suggest that like the
top discussion, what is happening is that there is energy stored in
the magnetic field of the current and as that field collapses it
transfers energy to the electrons orbiting in the wire coils. Thus
what happens is that extra field energy (above and beyond the simply
angular momentum of the circulating current is transferred to those
charges creating additional angular momentum. Sort of like the spring
transferring stored potential energy to the angular momentum of the
spinning top. |
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| Jim Black... |
| Posted: Mon Nov 02, 2009 1:53 am |
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On Sat, 31 Oct 2009 23:59:57 -0700 (PDT), Benj wrote:
[quote]On Oct 31, 10:47 pm, George Herold <ggher... at (no spam) gmail.com> wrote:
Benj, There's no real paradox. The angular momentum is carried in
the E-M fields. I'm not sure exactly how to calculate it, but if you
have the Feynman lectures I'm sure it's in there.
I"m sure there's no paradox. Feynman implies there is an answer.
However, he says that "We should warn you that the solution in not
easy, nor is it a trick. When you figure it out, you will have
discovered an important principle of electromagnetism."
Now if you search the internet on this question you find all manner of
wild calculations. People have done papers on the subject yet nobody
has actually answered the question. Just what "important principle" is
he talking about? Solutions range from angular momentum present in a
static electric field to the angular momentum present in "crossed" E
and M fields. None of this seems to be what Feynman was talking about.
So it seems that Feynman has stumped the entire physics community
including all the professionals, professors, and theoreticians. No one
else seems to get it either. That that it is any surprise that Feynman
was capable of doing this!
So if it's in the book, It's apparently buried pretty deep!
[/quote]
Chapter 27 (vol. 2), last paragraph.
--
Jim E. Black (domain in headers)
How to filter out stupid arguments in 40tude Dialog:
!markread,ignore From "Name" +"<email address>"
[X] Watch/Ignore works on subthreads |
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| George Herold... |
| Posted: Mon Nov 02, 2009 8:46 am |
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Guest
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On Nov 1, 1:59 am, Benj <bjac... at (no spam) iwaynet.net> wrote:
[quote]On Oct 31, 10:47 pm, George Herold <ggher... at (no spam) gmail.com> wrote:
Benj, There's no real paradox. The angular momentum is carried in
the E-M fields. I'm not sure exactly how to calculate it, but if you
have the Feynman lectures I'm sure it's in there.
I"m sure there's no paradox. Feynman implies there is an answer.
However, he says that "We should warn you that the solution in not
easy, nor is it a trick. When you figure it out, you will have
discovered an important principle of electromagnetism."
Now if you search the internet on this question you find all manner of
wild calculations. People have done papers on the subject yet nobody
has actually answered the question. Just what "important principle" is
he talking about? Solutions range from angular momentum present in a
static electric field to the angular momentum present in "crossed" E
and M fields. None of this seems to be what Feynman was talking about.
So it seems that Feynman has stumped the entire physics community
including all the professionals, professors, and theoreticians. No one
else seems to get it either. That that it is any surprise that Feynman
was capable of doing this!
So if it's in the book, It's apparently buried pretty deep! My
thinking goes like this: First off the electric field that rotates the
charge is NOT caused by the magnetic field of the coils! The magnetic
field is totally superfluous. The causality is between the current in
the coils and the E field at the hoop. The angular momentum of the
final motion is easy to see given the rotation and mas of the hoop,
but what and how is the angular momentum of the current in the coils.
The coils are still so they have no MECHANICAL momentum. Thus the only
possibility is for the original angular momentum to be due to motion
of the charges constituting a current and possibly the energy stored
in the magnetic field due to those circulating charges. Whether or not
the magnetic field actually contains angular momentum is not clear,
however, since the energy contained there does keep the charges
circulating longer than they would without that extra energy it is not
a stretch to imagine that this energy goes into extra current (charge
circulation) which in turn translates to extra angular momentum.
It's all not very simple.
[/quote]
Hi Benj, I never said it was simple. Can you give me the volume and
page number in the Fenyman lectures where this is discussed. I'll
look it up and read it (again). I'm 'pretty' sure that if you have a
static B field there is some angular momentum in the field. I'm not
at all sure how to calculate it. I do know that every photon can
carry one unit (h-bar) of angular momentum.
George H. |
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| George Herold... |
| Posted: Mon Nov 02, 2009 8:55 am |
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Guest
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On Nov 2, 1:53 am, Jim Black <fmla... at (no spam) organization.edu> wrote:
[quote]On Sat, 31 Oct 2009 23:59:57 -0700 (PDT), Benj wrote:
On Oct 31, 10:47 pm, George Herold <ggher... at (no spam) gmail.com> wrote:
Benj, There's no real paradox. The angular momentum is carried in
the E-M fields. I'm not sure exactly how to calculate it, but if you
have the Feynman lectures I'm sure it's in there.
I"m sure there's no paradox. Feynman implies there is an answer.
However, he says that "We should warn you that the solution in not
easy, nor is it a trick. When you figure it out, you will have
discovered an important principle of electromagnetism."
Now if you search the internet on this question you find all manner of
wild calculations. People have done papers on the subject yet nobody
has actually answered the question. Just what "important principle" is
he talking about? Solutions range from angular momentum present in a
static electric field to the angular momentum present in "crossed" E
and M fields. None of this seems to be what Feynman was talking about.
So it seems that Feynman has stumped the entire physics community
including all the professionals, professors, and theoreticians. No one
else seems to get it either. That that it is any surprise that Feynman
was capable of doing this!
So if it's in the book, It's apparently buried pretty deep!
Chapter 27 (vol. 2), last paragraph.
--
Jim E. Black (domain in headers)
How to filter out stupid arguments in 40tude Dialog:
!markread,ignore From "Name" +"<email address>"
[X] Watch/Ignore works on subthreads- Hide quoted text -
- Show quoted text -
[/quote]
Excellent, Thanks Jim The angular momentum is not in the B-field but
in the combination of charges and B-field, cute. (Think of a
situation where you have to move the charges into the 'all ready
existing' B-field.)
George H. |
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| Timo Nieminen... |
| Posted: Mon Nov 02, 2009 9:14 pm |
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On Mon, 2 Nov 2009, George Herold wrote:
[quote]On Nov 2, 1:53 am, Jim Black <fmla... at (no spam) organization.edu> wrote:
On Sat, 31 Oct 2009 23:59:57 -0700 (PDT), Benj wrote:
On Oct 31, 10:47 pm, George Herold <ggher... at (no spam) gmail.com> wrote:
Benj, There's no real paradox. The angular momentum is carried in
the E-M fields. I'm not sure exactly how to calculate it, but if you
have the Feynman lectures I'm sure it's in there.
I"m sure there's no paradox. Feynman implies there is an answer.
However, he says that "We should warn you that the solution in not
easy, nor is it a trick. When you figure it out, you will have
discovered an important principle of electromagnetism."
Now if you search the internet on this question you find all manner of
wild calculations. People have done papers on the subject yet nobody
has actually answered the question. Just what "important principle" is
he talking about? Solutions range from angular momentum present in a
static electric field to the angular momentum present in "crossed" E
and M fields. None of this seems to be what Feynman was talking about.
So it seems that Feynman has stumped the entire physics community
including all the professionals, professors, and theoreticians. No one
else seems to get it either. That that it is any surprise that Feynman
was capable of doing this!
So if it's in the book, It's apparently buried pretty deep!
Chapter 27 (vol. 2), last paragraph.
Excellent, Thanks Jim The angular momentum is not in the B-field but
in the combination of charges and B-field, cute. (Think of a
situation where you have to move the charges into the 'all ready
existing' B-field.)
[/quote]
The key principle is that moving energy has momentum, as Feynman
emphasises in the chapter. The angular momentum paradox is to show that
the mysterious circulating energy isn't just some figment of the Poynting
vector, but a real flow, with real momentum, and with real observable
implications.
One can get to this principle for the special case of electromagnetics by
calculating the energy flow and the momentum; this can be seen, for
example, in Jackson section 6.7. Feynman gives other specific
non-electromagnetic examples to suggest that it is a general principle.
The quickest route to the general principle is to consider the
energy-momentum 4-vector for some energy at rest, and look at how this
looks (via Lorentz transformation) when the energy is moving. But it's
older than relativity, and older than the Poynting vector, going back to
N.A. Umov, 1874 or so, who got there via thermodynamics.
George, you might like the old paper by Aguirregabiria and Hernandez, "The
Feynman paradox revisited", European J. Phys. 2, 168-170 (1981).
--
Timo |
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