HDTenEightyP/NetNews huggingface dataset:
From: draper@sscvx1.ssc.gov
Newsgroups: sci.physics
Subject: Re: terminal particle energy for accelerators
Date: 16 Apr 92 21:54:54 GMT
Distribution: world,local
Organization: Superconducting Super Collider Laboratory

In article <70425@ut-emx.uucp>, johncobb@ut-emx.cc.utexas.edu (John W. Cobb) writes:
> In article <1992Apr14.213121.17723@lmpsbbs.mot.com>,
> capurka@ssd.comm.mot.com (Tom Capurka) writes:
> |>Hello,
> |>I have a question about particle accelerators:  Why does there seem to be
> |>a terminal particle energy for a given particle, accelerator, related to
> |>the radius of the acclerator?  Is this because the radiation caused by...
> 
> Well, you coudn't put a colliding ring w/ SSC type energies into a box
> with getting a great deal of radiation. So the competing effect you
> describe above would be imensely increased...
> 
> You might think of some other tricks also. The two big problems you need to
> finesse are 1) a collider must reduce (or re-absorb?) its own radiation...

Just to reiterate a point I made earlier, the limitation for an SSC-type
machine is NOT the radiation, but the magnetic field used to constrain the beam
into a circle. The magnetic field required to collapse a 20TeV ring to the size
of a meter radius, whether it's electrons or protons or Buicks (the latter
suffering almost no synchrotron radiation at all), would be 60,000 Tesla!

Now in fact, for the SSC, the energies of the proton are high enough that
synchrotron energy losses are not completely ignorable (left as an exercise),
and this is why the magnets are not absolutely the strongest available...i.e.
the ring as designed was allowed to expand a little to lessen the losses due to
radiation. But believe me, the magnets will run out of steam long before you
ever worry about vaporizing the beam tube walls with gamma rays.

Paul Draper
University of Texas at Arlington
draper@sscvx1.ssc.gov
Mythink. Not UTAthink, not SSCthink, not GOVthink. Happy now?
From: anderson@fermi.phys.ualberta.ca (Warren G. Anderson)
Subject: Re: Interesting time travel paper
Organization: University Of Alberta, Edmonton Canada
Distribution: sci.physics
Date: Fri, 17 Apr 1992 14:13:01 GMT

In article <92107.140505DOCTORJ@SLACVM.SLAC.STANFORD.EDU>  
DOCTORJ@SLACVM.SLAC.STANFORD.EDU (Jon J Thaler) writes:
> srctran@world.std.com (Gregory Aharonian) says:
> 
> > March 28, 1992 issue of New Scientist, page 23, has an interesting
> > article reviewing an article in Physical Review D (October 1991) in which
> > David Deutsch of Oxford uses the many-worlds hypothesis to show how one can
> > how time travel without the paradoxes of killing your grandfather.  He
> > argues that if you could travel back in time, you would end in a parallel
> > universe, whose future you could affect, without affecting your own future.
> > Interesting articles.
> 
> You might look at this article, by Igor Novikov (now at the Copenhagen
> University Observatory):
> 
> THE JINN OF THE TIME MACHINE: NONTRIVIAL SELFCONSISTENT SOLUTIONS.
> By A. Lossev, I.D. Novikov (Nordita & Moscow, ITEP & Lebedev Inst.), 1991.
> NORDITA Copenhagen - NORDITA-91-41 (91,rec.Oct.) 20 p. (submitted to
> Class. Quantum Grav.).
> 
> I haven't read it, but I heard him give a talk with that title.  He argues
> that the lack of 'grandfather paradoxes' might just be a boundary condition
> that is automatically satisfied.  I don't recall that he discussed any
> specific mechanisms which might enforce this.

As a further added note, I know that Mike Morris (one of the people who's area
of specialty is Thorne wormholes) has also been looking at selfconsistent 
solution, although I don't know if he's published much about it. Kip Thorne is
also interested in such things, so you might want to do a literature search on  
him in the last 5 years or so too.

--
########################## _`|'_ ##############################################
##  Warren G. Anderson     |o o| "... for its truth does not matter, and is  ##
##  Dept. of Physics       ( ^ )  unimaginable." -J. Ashbery, The New Spirit ##
##  University of Alberta  /\-/\      (anderson@fermi.phys.ualberta.ca)      ##
From: gilligan@bldrdoc.gov (Jonathan M. Gilligan)
Newsgroups: sci.physics
Subject: Re: terminal particle energy for accelerators
Date: 17 Apr 92 02:02:32 GMT
Distribution: world,local
Organization: National Institute of Standards and Technology

In article <1992Apr16.155454.1@sscvx1.ssc.gov> draper@sscvx1.ssc.gov writes:
>Just to reiterate a point I made earlier, the limitation for an SSC-type
>machine is NOT the radiation, but the magnetic field used to constrain the beam
>into a circle. The magnetic field required to collapse a 20TeV ring to the size
>of a meter radius, whether it's electrons or protons or Buicks (the latter
>suffering almost no synchrotron radiation at all), would be 60,000 Tesla!

OK, maybe we can't get 20 TeV electrons into a meter even without
synchrotron radiation. However, although I'm a lowly atomic physicist
everyone I talk to in particle physics would prefer to look for new
particles with e+e- colliders, and there the practical limitation _is_
synchrotron radiation. The only reason to use protons, I'm told, is

1) to study proton structure

2) to avoid synchrotron losses

By the way, I can make my coffee cup move in a 1-meter circle at millions
of TeV with no difficulty (a million TeV = 0.1 Joule) so the only problem
with Buicks is making them small enough.

---Jon
From: jac@ds8.scri.fsu.edu (Jim Carr)
Newsgroups: sci.physics
Subject: Re: Heard of VIRTUAL PARTICLES???
Date: 13 Apr 92 15:33:32 GMT
Reply-To: jac@ds8.scri.fsu.edu (Jim Carr)
Organization: SCRI, Florida State University

In article <1992Apr9.233448.1@acad2.alaska.edu> assib@acad2.alaska.edu writes:
>The other day a friend of mine mentioned 'Virtual Particles...'
>Could I get some more info on this?
>
>If you have any feedback, send to:
>----------------------------------
>      ASSIB@ACAD2.ALASKA.EDU

I tried sending mail to this address, and it bounced.

"assib", if you are out there, send me mail and I will forward my reply. 

--
J. A. Carr                                    |  "The New Frontier of which I  
jac@gw.scri.fsu.edu                           |  speak is not a set of promises
Florida State University  B-186               |  -- it is a set of challenges."
Supercomputer Computations Research Institute |   John F. Kennedy (15 July 60)
From: columbus@strident.think.com (Michael Weiss)
Newsgroups: sci.physics
Subject: Re: Sciencists/politics (was Hawking speaks out ...)
Date: 9 Apr 92 09:48:25
Organization: Thinking Machines Corporation, Cambridge MA, USA
Distribution: world,local
	<8APR199214001279@sscvx1.ssc.gov> <9382@vice.ICO.TEK.COM>
NNTP-Posting-Host: strident.think.com
In-reply-to: hall@vice.ICO.TEK.COM's message of 8 Apr 92 22:35:51 GMT

In article <9382@vice.ICO.TEK.COM> hall@vice.ICO.TEK.COM (Hal Lillywhite)
writes: 

   Unfortunately movie stars can support political candidates or causes
   and people (including the media) give them coverage as though they
   knew something special.  Scientists usually don't get as much
   attention (unless they speak out in support of some popular or
   politically correct idea)....

Well, movie stars sometimes get elected, so maybe that makes their opinions
weightier than those of mere scientists :-))  [Or perhaps :-(( would
be more appropriate?]
Newsgroups: sci.physics
From: aankrom@isis.cs.du.edu (Anthony Ankrom)
Subject: Re: masers
Organization: Nyx, Public Access Unix at U. of Denver Math/CS dept.
Date: Tue, 14 Apr 92 17:48:29 GMT


 I know what a maser is, but no one seems to really use them any more. I
_don't_ know much ABOUT them. Lasers seem much more straighforward, and
maybe a little less tricky than masers. What I really want to do is to make
a mountain out of some molehills. I want to gang several magnetrons 
together and make a device that would shoot a very directional beam of
microwaves. (The magnetrons I have are all rated 2.5 GHz, I think.)
I just want something to experiment with. But I would like some input for
maybe a good driver circuit for several magnetrons. (Wonder how many can be
driven by the 15kV transformer from a microwave?) It's just something I
want to mess around with. I thought I'd ask for some input. I guess a
maser isn't what I really want to make, just something to use a bunch of
magnetrons in. (No. I don't want to make a RADAR system...)

St. Anthony



Newsgroups: sci.physics
From: capurka@ssd.comm.mot.com (Tom Capurka)
Subject: terminal particle energy for accelerators
Organization: Motorola LMPS
Distribution: world,local
Date: Tue, 14 Apr 1992 21:31:21 GMT
Summary: what is it
Keywords: n

Hello,
I have a question about particle accelerators:  Why does there seem to be
a terminal particle energy for a given particle, accelerator, related to
the radius of the acclerator?  Is this because the radiation caused by
the fact that the article is not in an inertial frame gets too large and
approaches equilibrium state with the energy input?
Whatever the reason, is there any possibility that there exists
a yet undiscovered trick around this so that one could have an SSC type
acclerator (as far as particle energies are concerned) in a 1 meter box?
Or is this impossible in principle, given the state of physics today.

Sorry if this is too basic but a good library is far away and this may turn
out to be more fun.

Regd's
Tom C.  <capurka@ssd.comm.mot.com>

From: pauls@trsvax.tandy.com
Date: 10 Apr 92 10:26 CDT
Newsgroups: sci.physics
Subject: Xeroxing mirrors
Message-ID: <8400009@trsvax>
Nf-ID: #N:trsvax:8400009:000:108
Nf-From: trsvax.tandy.com!pauls    Apr 10 10:26:00 1992


Can somebody explain this to me??

I tried to Xerox a flat mirror. The paper came out pitch black.

Well??
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: simple question
Date: 8 Apr 92 23:08:07 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

According to my Nuc. Phys. book, one must be careful to compare
C14 ratio to atmospheric C14 ratio of ~ 1940-50, as since then
atmospheric nuclear tests have put sufficient C14 into the air
to screw things up.

Kind of sad, don't you think?  Although possibly future
archaeologists will be able to deduce our weapons capabilities
from spikes in C14 (or thorium, or whatever) abundance ...

- Ben Weiner

If there ARE future archaeologists ...
Newsgroups: sci.physics
From: anderson@fermi.phys.ualberta.ca (Warren G. Anderson)
Subject: Re: What is space-time?
Organization: University Of Alberta, Edmonton Canada
Date: Thu, 9 Apr 1992 16:21:50 GMT

Where did all these physical philosophers come from all of a sudden?

In article <1992Apr9.023836.13990@csl.sri.com> ronnie@cisco.com (Ronnie B. Kon)  
writes:
> Consider a section of space-time which contains a perfect vacuum.

Section usually has a special meaning in space-time physics, but I assume
you mean a 4-D subset (maybe "chunk" would be good).

>  What is the space-time?

Mathematically, it is a 4-dimensional curved space. Physically, it is an
"arena" in which physical processes can take place.

>  Does it have temperature (3 degrees K)?

Depends what you mean by a vacuum. If it is classical and empty (neither of
which are likely to be true for chunks of space-time as we know it) then the
answer must be know (no energy --> no 3K photons). If you mean a chunk with
no massive particles (which is not possible even in the semi-classical limit)
then the photons in it at least have a 3K temperature. If you want even a
semi-classical (lowest order quantum effects) space-time, then you are 
beyond my ability to say (maybe some other's out there know).

>  How does it exist?

You'll have to be more specific.

>  It must be curved (in a relatavistic universe) so there must 
> be something to be curved. But if there is something, it must be 
> constructed of particles, so it can't be a vacuum. Or is space-time
> not constructed of particles? 

In classical space-time, space-time is not built out of particles. It simply
gives particles someplace to be (pardon the handwaving). It's existence is
seperate from the existence of particles.

> If not, what can it be constructed of? 

This is a pretty ambiguous question. What is matter constructed of? What is
energy constructed of? What is an electric field constructed of? These are
not questions that we can ask meaningfully at this point in physics.
 
> Will space-time and matter be unified one day?  (No, I don't expect a
> definitive yes.  Maybe a definitive no though).

I'll give you a definitive "perhaps" :-).

--
########################## _`|'_ ##############################################
##  Warren G. Anderson     |o o| "... for its truth does not matter, and is  ##
##  Dept. of Physics       ( ^ )  unimaginable." -J. Ashbery, The New Spirit ##
##  University of Alberta  /\-/\      (anderson@fermi.phys.ualberta.ca)      ##
Newsgroups: sci.physics
From: djconnel@leland.Stanford.EDU (Daniel Connelly)
Subject: Re: Xeroxing mirrors
Organization: DSG, Stanford University, CA 94305, USA
Date: Fri, 17 Apr 92 20:34:52 GMT

In article <10407@inews.intel.com> bhoughto@hopi.intel.com (Blair P. Houghton) writes:
>In article <8400009@trsvax> pauls@trsvax.tandy.com writes:
>>I tried to Xerox a flat mirror. The paper came out pitch black.
>What color is a mirror?

White.


Dan
-- 
Newsgroups: sci.physics
From: jim@cs.UAlberta.CA (Jim Easton)
Subject: Re: Question about dimmer switch and lamp.
Organization: University of Alberta, Edmonton, Canada
Distribution: na
Date: Thu, 16 Apr 1992 19:06:06 GMT

gsteckel@vergil.East.Sun.COM (Geoff Steckel - Sun BOS Hardware CONTRACTOR) writes:

>>    Given an incandescent lamp with a dimmer switch. The lamp is on.
>>...
>>    switch up, no matter how slow, the light always comes on rather
>>    suddenly and much brighter than in the reverse process .

>Yes, but it has to do with the circuit triggering the triac.
...

I disagreed with this but I am a great believer in letting experiment
settle these issues so last night I pulled the dimmer out of our dinning
room wall and wired it up on the kitchen table with a couple of
meters to see what was going on.

Sadly, it turns out I was wrong, at least partly, and that Geoff is
probably right - it is the hysteresis in the triac that is doing it.
(I hate being wrong)

My explanation was that it arises from the non-linearity of the light
bulb resistance with temperature.  Had I been correct then as I
turned the control from zero up to the point where the bulb comes on
I would have seen the current slowly increasing and at the point where
the bulb comes on the current would drop.  Instead the current remained
at the "quiescent" value until the light came on at which point it
suddenly jumped to values shown below.

Similarly going down when the bulb goes out the current should have
risen slighly but it dropped to about 1 Ma.  Interestingly immediately
after turning the control to zero the current drops to about 1 Ma but
then as time goes on (~30 seconds) the current rises to several Ma.
On one occasion the control was turned to zero and I was sitting there
wondering what I would do next when the bulb came on, full power.  I
turned the control just slightly off zero and it went out again.  Would
Geoff have an explanation for what happened there?

Following are the numbers that I got - if anyone's interested.  I have
arranged them in order of decreasing bulb resistance.

			current	bulb volts	calculated bulb
			(Ma)			resistance
	40 Watt bulb

full on			335	115		343
intermediate value	289	60 		207
up from zero - bulb on	237	35		147
down - bulb goes off	~120	~6		50
all the way down	1-4	~0		.03 (measured)

	100 Watt bulb

full on			850	115		135
intermediate		717	60		84
up from zero - bulb on	590	36		61
down - bulb goes off	~280	~5		17
all the way down	1-5	~0		.013 (measure)

The reason I said I was only partly wrong is because the bulb 
resistance is extremely non-linear and I have seen this effect
using a rheostat but that was quite a number of years ago.
Unfortunately I didn't have a rheostat of suitable value but I
am going to try to round one up.  In the meantime perhaps someone
who does have a rheostat of the right value could try it and let
us know what happens.

My expectation is that one would see the effect but it would be
much less pronounced than it is with the triac.

	Jim
Newsgroups: sci.physics
From: lepp@hal.lv-physics.nevada.edu (Stephen Lepp - Physics Faculty)
Subject: Re: "what's new" Apr-10-1992
Organization: UNLV Department of Physics
Date: Tue, 14 Apr 92 18:06:45 GMT

In article <1992Apr14.012809.8562@hsv3.uucp>, mvp@hsv3.uucp (Mike Van Pelt) writes:
|> 
|> In article <92101.162358WTU@psuvm.psu.edu> WTU@psuvm.psu.edu writes:
|> >WHAT'S NEW, Friday, 10 April 1992                  Washington, DC
|>  ...
|> >An Israeli Air Force expert said his study found no evidence that a
|> >Patriot ever took out an al Hussien warhead: "by that definition, the
|> >Patriot was a failure--and in a populated area there can be no other
|> >definition of success."  And yet, Israel is accused of selling Patriot
|> >technology to China.  Now that's a sale!
|> 
|> The fact that a screwdriver doesn't make a very good cold chisel
|> doesn't prove that it's a bad screwdriver, contrary to the logic
|> found in "What's New" columns like this one.
|> 
|> Those who don't subscribe to the "What's New" column's brand of
|> Politically Correct Know-Nothingism might consider it relevant that
|> the Patriot was designed for point defense.  Considering that area
|> defense of soft civilian targets was a use for which the missile was
|> never intended, akin to using a screwdriver for a cold chisel, it
|> performed pretty well.

But that still doesn't make it a good cold chisel (to use your analogy).
Seriously Park qualified his statement with 'in a populated area'.  I
think that Park may have a preference toward a witty statement rather
then a dull one everyone will be happy with.  If he didn't I doubt I 
would read his Whats New every week, I certainly wouldn't enjoy it
as much as I do.

Stephen Lepp
Newsgroups: sci.physics
From: srctran@world.std.com (Gregory Aharonian)
Subject: Interesting time travel paper
Organization: The World
Distribution: sci.physics
Date: Wed, 15 Apr 1992 14:34:24 GMT

    March 28, 1992 issue of New Scientist, page 23, has an interesting
article reviewing an article in Physical Review D (October 1991) in which
David Deutsch of Oxford uses the many-worlds hypothesis to show how one can
how time travel without the paradoxes of killing your grandfather.  He
argues that if you could travel back in time, you would end in a parallel
universe, whose future you could affect, without affecting your own future.
Interesting articles.

    By the way, almost all time-travel paradoxes involving death paradoxes
usually involve going back and killing your grandfather or father.  Aren't
we physicists supposed to be humanitarian and objective, and minimize the
destruction by going back and killing ourselves as children?

Just a thought  :-)

Gregory Aharonian
Source Translation & Optimization
From: hall@vice.ICO.TEK.COM (Hal Lillywhite)
Newsgroups: sci.physics
Subject: Sciencists/politics (was Hawking speaks out ...)
Date: 8 Apr 92 22:35:51 GMT
Distribution: world,local
Organization: Tektronix Inc., Beaverton, Or.

In article <8APR199214001279@sscvx1.ssc.gov> sawyer@sscvx1.ssc.gov (Lee Sawyer) writes:

>                                 However can you imagine the response
> if Leon Lederman or Phillip Anderson spoke on the presidential race ?
> He would be crucified by the media, if they paid any attention at all.

Well, pretty much anybody of any stature who speaks out on politics
will get crucified by the media.  Sometimes you just have to pay the
price if you are going to make a contribution.  I'm more concerned
about your last phrase, "If [the media] paid any attention at all."
Unfortunately movie stars can support political candidates or causes
and people (including the media) give them coverage as though they
knew something special.  Scientists usually don't get as much
attention (unless they speak out in support of some popular or
politically correct idea).  Jane Fonda has a lot more influence on
the nuclear power plant issue than do the people who really know
something about the issue.
Newsgroups: sci.physics
From: cooper@cbnewsg.cb.att.com (Ralph 'Hairy' Moonen)
Subject: Re: Time
Summary: time, energy
Organization: AT&T
Date: Wed, 8 Apr 1992 11:27:55 GMT

In article <1992Apr8.071015.17512@ifi.uio.no>, jarlo@ifi.uio.no (Jarl Magne Michael stensen) writes:
> I would want to ask all of you this wery simple (?) question: what is time?

Hmm.. I have had a couple of thoughts on the "what is time" question, and for
what I can think of, time is a carrier for energy. If you want to get energy
from A to B then you will need to "transport" it. This transportation occurs
with a "speed". Time is the carrier. The amount of time multiplied with the
reciprocal of the distance gives you this "speed".

Analogy: just like information can be carried by electromagnetic carriers,
energy is carried by time.


> I asked Him what Time was, He just looked at His watch and asked me to come
> back tomorrow.

That's weird.... I asked Him the same question tomorrow, and he told me to 
come back yesterday.....

--Ralph Moonen
--rmoonen@hvlpa.att.com
From: jac@ds8.scri.fsu.edu (Jim Carr)
Newsgroups: sci.physics
Subject: Re: terminal particle energy for accelerators
Keywords: n
Date: 15 Apr 92 13:55:31 GMT
Reply-To: jac@ds8.scri.fsu.edu (Jim Carr)
Distribution: world,local
Organization: SCRI, Florida State University

In article <1992Apr14.213121.17723@lmpsbbs.mot.com> capurka@ssd.comm.mot.com (Tom Capurka) writes:
>Hello,
>I have a question about particle accelerators:  Why does there seem to be
>a terminal particle energy for a given particle, accelerator, related to
>the radius of the acclerator?  Is this because the radiation caused by
>the fact that the article is not in an inertial frame gets too large and
>approaches equilibrium state with the energy input?

Yes.

And this "bremsstrahlung" (literally 'braking-radiation') that arises from 
acceleration of the particle around a curve depends on mass.  Hence an 
electron synchrotron must have a larger radius than a proton synchrotron 
with the same energy.  

>Whatever the reason, is there any possibility that there exists
>a yet undiscovered trick around this so that one could have an SSC type
>acclerator (as far as particle energies are concerned) in a 1 meter box?

Highly unlikely.  What people are working on are compact linear 
accelerators (where this problem will not appear).  The effort is on  
the development of RF cavities that provide extremely high electric 
field gradients while maintaining good beam properties. 

>Sorry if this is too basic but a good library is far away and this may turn
>out to be more fun.

The best source is probably articles in Physics Today, where you can see 
nice color pictures of things like RF quadrupoles.  There was a cover story 
some years back and occaisional news stories about things like planned 
linear colliders.  Maybe one of the SLAC HEP-cats can add some to this. 
I think the former USSR was planning to build one at Serpukhov. 

--
J. A. Carr                                    |  "The New Frontier of which I  
jac@gw.scri.fsu.edu                           |  speak is not a set of promises
Florida State University  B-186               |  -- it is a set of challenges."
Supercomputer Computations Research Institute |   John F. Kennedy (15 July 60)