Well, it's Sunday evening again. I'm sick of studying for maths and IT exams - what I've been doing all week - so I'll take some time off, and look at harmonics.

Let's recall our good friend the sine wave:

Here the signal rose and fell between some extremes - the amplitude. It did so in a certain time - the period - which ( when measured in seconds ) if you took the reciprocal, you got the frequency.

Let's look at what happens if we change the frequency only - by some exact/integral multiples:

Now with another friend, the Fourier Transform, we can describe this behaviour thus:

As a general rule for pretty well any wave-like phenomenon, the energy in a given waveform increases with frequency. For light that is certainly true ( with E = Energy, h = Planck's constant, and v = frequency. * means multiply ):

E = h * v

Many resonant systems/behaviours tend to distribute energy in a number of multiples of a given frequency, but because the higher frequencies 'cost' more energy then each of those is less 'affordable'. Also the higher frequencies usually decay and subside quicker, with the energy being dealt into some other form. Check this out, from Livingstone:

which indicates energy at peaks of 60Hz, 120Hz, 180Hz, 240Hz and 300Hz. This is the fundamental and harmonics of the alternating current power supply frequency in the US.

Try these ones, from Hanford:

which demonstrate a so called 'violin mode' of oscillation, and many harmonics. Note how the same 'structure' of the lowest frequency pattern is preserved. Also see how the amplitude, with each increase in frequency, steadily goes down and in this plot ( for the ninth harmonic ) is hardly above the forest of noise:

Of course, a really good question is why do such multiples exist? But that'll be another day.... :-)

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

Also mention of an earthquake (in Argentina, mag 6.4) just prior to the trouble with the wind.

Not too much trouble with the weather at Livingston, but there are the usual trains. The interferometer was is Science Mode during a gamma-ray burst, and the elog mentioned multiple notifications from the same satellite. I checked the GRB Real-time Sky Map and, sure enough, the SWIFT satellite bagged a couple more (although their descriptions aren't listed yet at the time of this post)...

I also noticed that the NS/NS Inspiral Range for Livingston is creeping towards 14 Mpc (since the last few weeks). But there was also mention of more logging... at Livingston? Sounds like something Hanford would have to deal with; but at Hanford, they actually had to contend with noise from a baling machine, which was baling tumbleweeds. Sounds like that time of year... :)

OK, so here's what you get from those prolonged high winds around Hanford ( mid-X station is shown at the top left, and the Y arm in the deep background going across the top ):

and here ( end-X station at upper right ):

and also here ( at LVEA/corner station ):

for which there is a good chap by the name of Oscar who is doing the baling. At least they aren't Triffids! :-)
It looks like land retention/reclamation efforts in the foregrounds of the arm shots, probably tumbleweed bales tied together me thinks...
You can see the hemi-cylindrical concrete tunnels enclosing our precious beams, I think the large upright cylindrical tanks are for coolant storage?
There have been long locked periods for all IFO's last 24 hours. :-)
Cheers, Mike.

( NB. Photos by Corey Gray - thank you )

( edit ) Here's one of Mr Gray himself:

- Hmmm, tricky to caption that one..... err ..... How many physicists does it take to change a light globe? :-)

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

## Well, it's Sunday evening

)

Well, it's Sunday evening again. I'm sick of studying for maths and IT exams - what I've been doing all week - so I'll take some time off, and look at harmonics.

Let's recall our good friend the sine wave:

Here the signal rose and fell between some extremes - the amplitude. It did so in a certain time - the period - which ( when measured in seconds ) if you took the reciprocal, you got the frequency.

Let's look at what happens if we change the frequency only - by some exact/integral multiples:

Now with another friend, the Fourier Transform, we can describe this behaviour thus:

As a general rule for pretty well any wave-like phenomenon, the energy in a given waveform increases with frequency. For light that is certainly true ( with E = Energy, h = Planck's constant, and v = frequency. * means multiply ):

E = h * v

Many resonant systems/behaviours tend to distribute energy in a number of multiples of a given frequency, but because the higher frequencies 'cost' more energy then each of those is less 'affordable'. Also the higher frequencies usually decay and subside quicker, with the energy being dealt into some other form. Check this out, from Livingstone:

which indicates energy at peaks of 60Hz, 120Hz, 180Hz, 240Hz and 300Hz. This is the fundamental and harmonics of the alternating current power supply frequency in the US.

Try these ones, from Hanford:

which demonstrate a so called 'violin mode' of oscillation, and many harmonics. Note how the same 'structure' of the lowest frequency pattern is preserved. Also see how the amplitude, with each increase in frequency, steadily goes down and in this plot ( for the ninth harmonic ) is hardly above the forest of noise:

Of course, a really good question is why do such multiples exist? But that'll be another day.... :-)

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

## There was trouble with the

)

There was trouble with the wind, at Hanford, with some gusts clocked at 80 mph.

Last couple days, as measured at the Laser Vacuum and Equipment Area:

[img]http://groups.msn.com/_Secure/0TAAeDygXfZiOjjtmo*bdPkOviBvV74!*u3x1URUSakeoT8keYfbynFPGjmwDO39!qHavM3NQPe5B9kDXqAO0UgdgIxXEtnqhoF7czH74q1LPUBJd3fTIQQ/HanfordWind.jpg?dc=4675597710326653025[/img]

The red plot is max, green is min, and the plot between is the mean

Also mention of an earthquake (in Argentina, mag 6.4) just prior to the trouble with the wind.

Not too much trouble with the weather at Livingston, but there are the usual trains. The interferometer was is Science Mode during a gamma-ray burst, and the elog mentioned multiple notifications from the same satellite. I checked the GRB Real-time Sky Map and, sure enough, the SWIFT satellite bagged a couple more (although their descriptions aren't listed yet at the time of this post)...

I also noticed that the NS/NS Inspiral Range for Livingston is creeping towards 14 Mpc (since the last few weeks). But there was also mention of more logging... at Livingston? Sounds like something Hanford would have to deal with; but at Hanford, they actually had to contend with noise from a baling machine, which was baling tumbleweeds. Sounds like that time of year... :)

## OK, so here's what you get

)

OK, so here's what you get from those prolonged high winds around Hanford ( mid-X station is shown at the top left, and the Y arm in the deep background going across the top ):

and here ( end-X station at upper right ):

and also here ( at LVEA/corner station ):

for which there is a good chap by the name of Oscar who is doing the baling. At least they aren't Triffids! :-)

It looks like land retention/reclamation efforts in the foregrounds of the arm shots, probably tumbleweed bales tied together me thinks...

You can see the hemi-cylindrical concrete tunnels enclosing our precious beams, I think the large upright cylindrical tanks are for coolant storage?

There have been long locked periods for all IFO's last 24 hours. :-)

Cheers, Mike.

( NB. Photos by Corey Gray - thank you )

( edit ) Here's one of Mr Gray himself:

- Hmmm, tricky to caption that one..... err ..... How many physicists does it take to change a light globe? :-)

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

## A powerful earthquake blew

)

A powerful earthquake blew off all the IFO's - 7.8 on the Richter between Japan & Kamchatka - phew!

Anyhows, time for a respawn ....

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal