Defining *Event*? (kst)

Comments, notions references invited.

I have yet to see a good physical definition of
*event*, yet that term is bandied about as if it
is known.

Thanks in Advance
Ken S. Tucker

PS: Snippable notes...
An event is digital like 1,0 - either the lamp
is turned on or it's not, events aren't fractional,
they're an invariant like 1 or 0. But event requires
a real physical description based on real physical
finite quantities like

Dx, Dy, Dz, Dt, De (e=energy)

(D means finite increment)
to be realistically measureable.

We can get a D(rho) =Dx*Dy*Dz*Dt
(see Dover's P of R pg 129 Eq.18,
D(rho) is a spacetime volume),
that transforms as,

D(rho')*sqrt(g') = D(rho)*sqrt(g)

where g = det |g_uv|.

Setting DV = D(rho)*sqrt(g) simplifies to

DV '= DV which is invariant.

And employing a CS where g =1-v^2
(v = velocity) and De = rest energy then

De/sqrt(g) = De'/sqrt(g')

is invariant energy.

Setting DE = De/sqrt(g) simplifies to

DE' = DE which is invariant.

Then the Event Invariant is defined by,

DV * DE = DV' * DE'

=Dx *Dy *Dz *Dt *De

=Dx'*Dy'*Dz'*Dt'*De' ,

where these last two equations are the
*coordinate specific* increment.
This statement can be refined by defining
De and De' as increments to the rest energy
w.r.t CS K and K' respectively.

The invariant change in energy density is,

DE/DV = DE'/DV' .

as in +/- photons (DE) per volume (DV).

Expanding to specific CS's K and K',

DE/DV = (1/g)*De/D(rho)=(1/g')*De'/D(rho').

and connects the Event Equation with Einsteins
Field Equation G_uv =k*T_uv, (EFE) via density
transforms. This means |G_uv| has the same
density as De/D(rho).
That's good, because an *invariant event*
is defined in accord with Einsteins Law, to the
resolution of relative tensor density .
The Event definition can be connected indice
by indice with EFE's. It may be easier to find
EFE's as a solution to an Event, and the EFE's
become a solution of the definition of an Event.

Apparently EVENT= DE*DV is identical in
QM and GR.
KST

Ken S. Tucker:
Defining *Event*? (kst)

Comments, notions references invited.

I have yet to see a good physical definition of
*event*, yet that term is bandied about as if it
is known.

Spacetime point.

(Ken S. Tucker) wrote in message . com...
Defining *Event*? (kst)

Comments, notions references invited.

I have yet to see a good physical definition of
*event*, yet that term is bandied about as if it
is known.

http://dictionary.reference.com/search?q=event

event
n.

(Perfectly Innocent) wrote in message . com...

Thanks bilge and Innocent, for your replies.

Ken S. Tucker:
Defining *Event*? (kst)
I have yet to see a good physical definition of
*event*, yet that term is bandied about as if it
is known.

Spacetime point.
bilge

That's imaginary, it's not physicaly measureable.

Innocent writes,
http://dictionary.reference.com/search?q=event
event
n.
Something that takes place; an occurrence.
A significant occurrence or happening.

Illustration:
Imagine that every location in the universe can be assigned a triple
of numbers, (x,y,z). Now imagine that every location has a clock. If
you want to be conventional, imagine that the clocks are synchronized.
(It doesn't matter how you synchronize your clocks. Pick whatever
clock synchronization scheme you like). Now suppose something happens
at the location (x,y,z). The happening can be anything sudden: a
button is pushed, a bullet is fired or a flashbulb goes off. If the
happening at (x,y,z) coincides with the clock there reading time t,
then (x,y,z,t) is an event.

Agreed. But the events you've described by
"sudden" all need a detectable (non-zero)
change in energy. Given this quantity is the
increment De, then a period of time greater
than zero describes the Power of the event
to be 0 De/Dt oo (infinity).

So the time coordinate of the event would be
t+Dt , similiarily (x+Dx, y+Dy, z+Dz).

To simplify, let's choose a CS where the
origin is at x,y,x,t so that x=y=z=t=0.

Then the *event* is a finite Space-Time
Interval (STI) defined by Dx, Dy, Dz, Dt.

This makes good sense. So extending the
event provides the STI so the event is the
same as the interval. (Instead of the usual
definition of separate events defining the STI).

I'll venture a test of this conjecture.
Go look at a star 10 Light Years away.

For any knowledge of the emission of light
from the star to occur to you, then emission
is followed by absorption in your eye.

That same star, reduced in Power output,
can be moved to be an inch away from your
eye, and the same observation results.
So relative to your observations, the same
event occured.

We usually think in terms of distance to be
physically real, but this is an imaginary
abstraction when the Physical Laws of Nature
are formulated. After all a rock obeys natural
law and can only do that wrt what it receives.

I think that's partly why Einstein's Equation
describes physical effects with a local (within
the rocks volume) by G_uv = k*T_uv.
The solution of this is our abstraction.

Regards
Ken S. Tucker

Ken S. Tucker:
(Perfectly Innocent) wrote in message . com...

Thanks bilge and Innocent, for your replies.

Ken S. Tucker:
Defining *Event*? (kst)
I have yet to see a good physical definition of
*event*, yet that term is bandied about as if it
is known.

Spacetime point.
bilge

That's imaginary, it's not physicaly measureable.

I don't really care what it is. You asked for the definition and
that it was I gave you as relativity textbooks define it. You can
either use the term as it's defined and invent new ones for whatever
personal issues you have with the definition everyone else uses,
or you can use the term `event' differently than everyone else
does and be misunderstood. Your objection is equivalent to saying
you think the word "duck" sounds more like it describes a large furry
mammal with antlers and a tail rather a bird with feathers and webbed
feet that lives around lakes and ponds. Nobody is going to understand
that the herds of ducks you describe roaming the wilderness are
what everyone else calls elk.

(Bilge) wrote in message ...

Ken S. Tucker:
(Perfectly Innocent) wrote in message . com...

Thanks bilge and Innocent, for your replies.

Ken S. Tucker:
Defining *Event*? (kst)
I have yet to see a good physical definition of
*event*, yet that term is bandied about as if it
is known.

Spacetime point.
bilge

That's imaginary, it's not physicaly measureable.

I don't really care what it is. You asked for the definition and
that it was I gave you as relativity textbooks define it.

Ahhhh, "relativity textbooks", would your quoted
definition be true in quantum theory textbooks?
((In this question I think you would very well
qualified to render a QM opinion)).

You can
either use the term as it's defined and invent new ones for whatever
personal issues you have with the definition everyone else uses,
or you can use the term `event' differently than everyone else
does and be misunderstood. Your objection is equivalent to saying
you think the word "duck" sounds more like it describes a large furry
mammal with antlers and a tail rather a bird with feathers and webbed
feet that lives around lakes and ponds. Nobody is going to understand
that the herds of ducks you describe roaming the wilderness are
what everyone else calls elk.

Understood and thanks, I'll add ducks may
be descended from dinosaurs. Definitions
evolve, to suit the application and as a kind
of fusion between QM and GR is evolving,
there does seem to be a need to define
*event* consistently across physics disciplines.
Thanks and Regards
Ken S. Tucker

Ken S. Tucker:
(Bilge) wrote in message
e-al.net...

I don't really care what it is. You asked for the definition and
that it was I gave you as relativity textbooks define it.


Ahhhh, "relativity textbooks", would your quoted definition be true in
quantum theory textbooks? ((In this question I think you would very well
qualified to render a QM opinion)).

"Event" is not a quantum mechanical term. It's a term that applies
to spacetime coordinates. Quantum mechanics lives in hilbert space.
That's why I said you should invent your own terminology rather
than reinvent a definition for something which has a well defined
meaning. It's bad enough that different well-defined conventions
exists for the same terms that have the same meanings (esp in fields
which make use of a lot of quantum mechanics). Don't confuse things
by redefining a term no one is confused about, regardless of whether
you think it's an improvement. An "improvement" deserves its own
word.

Igor wrote in message . ..
On Sun, 16 Nov 2003 06:04:36 -0000,
(Bilge) wrote:

Ken S. Tucker:
(Bilge) wrote in message
e-al.net...
I don't really care what it is. You asked for the definition and
that it was I gave you as relativity textbooks define it.

Ahhhh, "relativity textbooks", would your quoted definition be true in
quantum theory textbooks? ((In this question I think you would very well
qualified to render a QM opinion)).

"Event" is not a quantum mechanical term. It's a term that applies
to spacetime coordinates. Quantum mechanics lives in hilbert space.
That's why I said you should invent your own terminology rather
than reinvent a definition for something which has a well defined
meaning. It's bad enough that different well-defined conventions
exists for the same terms that have the same meanings (esp in fields
which make use of a lot of quantum mechanics). Don't confuse things
by redefining a term no one is confused about, regardless of whether
you think it's an improvement. An "improvement" deserves its own
word.

Agreed. We can define an event in classical as something occuring at
some point in 3-space, in relativity as something at a point in 3+1
spacetime. IN QM, we tend to lose those precious local properties,
and the Hilbert space tends to obscure the issue even further. But I
tend to believe that, since the wave function is about the only real
deterministic element of QM, it most likely would be the best place to
begin for defining such an event.

Agreed
Usually greek PSI represents "wave function",
I'll denote by W, and use $ as an integral then,

$$$ W*W dx dy dz =1

is the conventional probability normalization,
and is invariant in 3D.

Please do not be too harsh, but I think an
invariant in GR would require 4D, but the
above lacks dt, and so appears Newtonian
in conception to me, and so it's usefulness
as a real spacetime invariant is questionable,
but that does not make it wrong.

We could have solutions in differing
dimensionality like,

$$$ W*W dx dy dz =1

is simultaneous with

$$$$ w*w dx dy dz dt =1, where

w*w is the particles energy/(4D volume)
(4D energy density) and then integrated
in 4D that particle becomes ONE.

Now it stands to reason (I think) that a
tensor like k*T_uv integrated over all of
spacetime will produce a finite quantity
corresponding to the field produced by
the particle, or in juxtaposition this entire
field creates and defines the particle,
depending on interpretation.

I'll stop here pending comment and thanks
Ken S. Tucker

(Perfectly Innocent) wrote in message . com...
(Ken S. Tucker) wrote in message . com...
Defining *Event*? (kst)

Comments, notions references invited.

I have yet to see a good physical definition of
*event*, yet that term is bandied about as if it
is known.

http://dictionary.reference.com/search?q=event

event
n.
Something that takes place; an occurrence.
A significant occurrence or happening.

Illustration:

Imagine that every location in the universe can be assigned a triple
of numbers, (x,y,z). Now imagine that every location has a clock. If
you want to be conventional, imagine that the clocks are synchronized.
(It doesn't matter how you synchronize your clocks. Pick whatever
clock synchronization scheme you like). Now suppose something happens
at the location (x,y,z). The happening can be anything sudden: a
button is pushed, a bullet is fired or a flashbulb goes off. If the
happening at (x,y,z) coincides with the clock there reading time t,
then (x,y,z,t) is an event.

http://www.everythingimportant.org/viewtopic.php?t=648

Eugene Shubert

Sounds good to me. Here is how I defined "event" in Taylor and
Wheeler's text "Exploring Black Holes"

"event - A location in space at an instant in time; that is, a point
in spacetime. A firecracker explosion is an example of an event. The
explosion fixes both a position in space and a time."

The "a point in spacetime" part was not meant to be a definition
though. The definition of 'spacetime' is defined in terms of events,
i.e.

"spacetime - Arena in which events take place. [...]"

That, of course, means the set of all places and all times.

Pmb

(Ken S. Tucker) wrote:
Spacetime point.
bilge
That's imaginary, it's not physicaly measureable.

Counter-example:

Longitude: 90 deg. 0' 0'' west
Latitude: 45 deg. 0' 0'' north
Altitude: 200 meters above surface
Time: 12:00 Midnight, CST, January 1, 2001.

A physical measurement of an event.