I thought this idea had died when Kare stopped updating her report
but ...

https://phys.org/news/2022-02-laser-mars.html

There's one bit that bugs me though - they talk about running 100
megawatts of lasers (in a ten metre diameter beam) for an hour (well 58
minutes) to push a tonne to 17kps. I make that 40% of the electricity going
into ground based lasers winding up as kinetic energy in a one tonne
payload - I have trouble believing in that much efficiency.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

Yes especially since you will heat the atmosphere or in a vacuum you start
to hit quantum effects that still means you cannot focus your beam properly.
I often wonder where these ideas come from? Is it frustration about the
speed of light or what?
This speed of light thing seems to me to be a very curious thing.
The limit is mainly put there by the effective mass of accelerating
matter, and as photons are light, and have little mass, getting them to go
faster would be difficult. It almost points to the universe having a
processor whose speed is artificially governing the environment. If there
really is a multiverse, might there be one with a different speed of light?
Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"Ahem A Rivet's Shot" <steveo@eircom.net> wrote in message
news:20220210144157.25e993a1301690fb807d4273@eircom.net...
> I thought this idea had died when Kare stopped updating her report
> but ...
>
> https://phys.org/news/2022-02-laser-mars.html
>
> There's one bit that bugs me though - they talk about running 100
> megawatts of lasers (in a ten metre diameter beam) for an hour (well 58
> minutes) to push a tonne to 17kps. I make that 40% of the electricity
> going
> into ground based lasers winding up as kinetic energy in a one tonne
> payload - I have trouble believing in that much efficiency.
>
> --
> Steve O'Hara-Smith
> Odds and Ends at http://www.sohara.org/

On Fri, 11 Feb 2022 09:56:30 -0000
"Brian Gaff \(Sofa\)" <briang1@blueyonder.co.uk> wrote:

> Yes especially since you will heat the atmosphere or in a vacuum you
> start to hit quantum effects that still means you cannot focus your beam
> properly. I often wonder where these ideas come from? Is it frustration
> about the speed of light or what?

They're only using it for launch not long range so the focusing
requirements are not too difficult (a lot easier than putting a spot on the
moon). Small laser propulsion tests have been going on since the 1960s, the
new twists today are cheap high efficiency LEDs, fibre optic lasers (also
cheap and high efficiency) and phased arrays at inrared frequencies (which
is just awesome to contemplate) - a lot of Kare's costs went into steerable
optics so that last a big cost cutter.

The speed of light has nothing to do with it, this is all about
leaving the fuel tanks on the ground while launching the rocket. I'm sure
it can work, I just think they're fibbing a bit about the numbers - 100
megawatts of light output might well do it (that obscenely high temperature
hydrogen will make a very efficient drive). It probably need more like
3-500 megawatts of electricity to make it work - say $30-$50 per kilo to
Mars transfer, not bad at all!

TAAAW of course a one tonne payload is too small to be useful on
it's own. It might just be possible to make a one person lander that small -
but it would be a nasty immobile 45 days in something not much bigger than
a car that is almost entirely heat shield (for the 8G aerobraking at Mars)
and supplies with a person shaped cavity in the middle. The person had
better ride in induced coma otberwise they will not arrive sane - alive is
questionable IMHO. It makes the mass allowance for the first lunar landing
look luxurious.

A rather more practical approach might be to design a modular
powered lander that assembles en-route first into transit mode then into
landing mode. Some engines, some fuel tanks, some life support, some people,
some inflatable living space for the transit all in one tonne modules.

> This speed of light thing seems to me to be a very curious thing.
> The limit is mainly put there by the effective mass of accelerating
> matter, and as photons are light, and have little mass, getting them to

Photons travel at the speed of light because they have *no* rest
mass not little mass but none at all. The multiplier on observed mass as
relative speed increases goes to infinity at the speed of light so it
requires infinte energy to accelerate anything with mass to the speed of
light.

Things with no rest mass can only have mass at the speed of light
and so things with no rest mass must move at the speed of light relative to
everything (that light does this was experimentally verified by the
Michaelson/Morely experiment). It took Poincare, Lorentz, Fitzgerald and
finally Einstein (among others but their's were the main insights and of
course Einstein pulled it all together) to make sense out of that
observation.

> go faster would be difficult. It almost points to the universe having a

Not difficult, impossible. Photons can only exist by being at the
speed of light relative to everything. As for faster - either the theory
breaks down or the concept of imaginary (in the square root of -1 sense)
mass has meaning - either way slower than light and faster than light are
separated by an infinitely high barrier at the speed of light only massless
particles can dance on the fence and they can't get anywhere else.

One more thought for you, from the perspective of a photon the
universe is an infinitely thin flat sheet, the photon is a fixed point on
that sheet and there is no time.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

Yes heard that before, but the problem I have is if they have no mass, how
come we can detect them at all. The last thread was talking about propulsion
using lasers, which if they can exert a force on a mass,howcan they have it
both ways?

Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"Ahem A Rivet's Shot" <steveo@eircom.net> wrote in message
news:20220211110956.76c1f86ee26fd2b8f94425c8@eircom.net...
> On Fri, 11 Feb 2022 09:56:30 -0000
> "Brian Gaff \(Sofa\)" <briang1@blueyonder.co.uk> wrote:
>
>> Yes especially since you will heat the atmosphere or in a vacuum you
>> start to hit quantum effects that still means you cannot focus your beam
>> properly. I often wonder where these ideas come from? Is it frustration
>> about the speed of light or what?
>
> They're only using it for launch not long range so the focusing
> requirements are not too difficult (a lot easier than putting a spot on
> the
> moon). Small laser propulsion tests have been going on since the 1960s,
> the
> new twists today are cheap high efficiency LEDs, fibre optic lasers (also
> cheap and high efficiency) and phased arrays at inrared frequencies (which
> is just awesome to contemplate) - a lot of Kare's costs went into
> steerable
> optics so that last a big cost cutter.
>
> The speed of light has nothing to do with it, this is all about
> leaving the fuel tanks on the ground while launching the rocket. I'm sure
> it can work, I just think they're fibbing a bit about the numbers - 100
> megawatts of light output might well do it (that obscenely high
> temperature
> hydrogen will make a very efficient drive). It probably need more like
> 3-500 megawatts of electricity to make it work - say $30-$50 per kilo to
> Mars transfer, not bad at all!
>
> TAAAW of course a one tonne payload is too small to be useful on
> it's own. It might just be possible to make a one person lander that
> small -
> but it would be a nasty immobile 45 days in something not much bigger than
> a car that is almost entirely heat shield (for the 8G aerobraking at Mars)
> and supplies with a person shaped cavity in the middle. The person had
> better ride in induced coma otberwise they will not arrive sane - alive is
> questionable IMHO. It makes the mass allowance for the first lunar landing
> look luxurious.
>
> A rather more practical approach might be to design a modular
> powered lander that assembles en-route first into transit mode then into
> landing mode. Some engines, some fuel tanks, some life support, some
> people,
> some inflatable living space for the transit all in one tonne modules.
>
>> This speed of light thing seems to me to be a very curious thing.
>> The limit is mainly put there by the effective mass of accelerating
>> matter, and as photons are light, and have little mass, getting them to
>
> Photons travel at the speed of light because they have *no* rest
> mass not little mass but none at all. The multiplier on observed mass as
> relative speed increases goes to infinity at the speed of light so it
> requires infinte energy to accelerate anything with mass to the speed of
> light.
>
> Things with no rest mass can only have mass at the speed of light
> and so things with no rest mass must move at the speed of light relative
> to
> everything (that light does this was experimentally verified by the
> Michaelson/Morely experiment). It took Poincare, Lorentz, Fitzgerald and
> finally Einstein (among others but their's were the main insights and of
> course Einstein pulled it all together) to make sense out of that
> observation.
>
>> go faster would be difficult. It almost points to the universe having a
>
> Not difficult, impossible. Photons can only exist by being at the
> speed of light relative to everything. As for faster - either the theory
> breaks down or the concept of imaginary (in the square root of -1 sense)
> mass has meaning - either way slower than light and faster than light are
> separated by an infinitely high barrier at the speed of light only
> massless
> particles can dance on the fence and they can't get anywhere else.
>
> One more thought for you, from the perspective of a photon the
> universe is an infinitely thin flat sheet, the photon is a fixed point on
> that sheet and there is no time.
>
> --
> Steve O'Hara-Smith
> Odds and Ends at http://www.sohara.org/

On Sat, 12 Feb 2022 14:19:48 -0000
"Brian Gaff \(Sofa\)" <briang1@blueyonder.co.uk> wrote:

> Yes heard that before, but the problem I have is if they have no mass,

They have no rest mass, but they can have relativistic mass at the
speed of light. Which essentially means that they can only exist by going at
the speed of light relative to everything.

> how come we can detect them at all. The last thread was talking about

They have mass when they move at the speed of light and only then,
because infinity times zero equals something indertiminate. So we can only
detect them and they can only exist at the speed of light where they do
have mass proportionate to the energy they carry.

> propulsion using lasers, which if they can exert a force on a mass,howcan
> they have it both ways?

Now you know.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

On 12/02/2022 15:51, Ahem A Rivet's Shot wrote:
> On Sat, 12 Feb 2022 14:19:48 -0000
> "Brian Gaff \(Sofa\)" <briang1@blueyonder.co.uk> wrote:
>
>> Yes heard that before, but the problem I have is if they have no mass,
>
> They have no rest mass, but they can have relativistic mass at the
> speed of light. Which essentially means that they can only exist by going at
> the speed of light relative to everything.
>
>> how come we can detect them at all. The last thread was talking about
>
> They have mass when they move at the speed of light and only then,
> because infinity times zero equals something indertiminate.

Basic maths suggest that infinity times zero =1
:-)

(In case you didn't get that, try rearranging the formula One divided by
Zero equals... <G>)

HTH, Chris

On Sat, 12 Feb 2022 16:33:01 +0000
"ChrisND@privacy.net" <chrisnd@privacy.net> wrote:

> On 12/02/2022 15:51, Ahem A Rivet's Shot wrote:
> > On Sat, 12 Feb 2022 14:19:48 -0000
> > "Brian Gaff \(Sofa\)" <briang1@blueyonder.co.uk> wrote:
> >
> >> Yes heard that before, but the problem I have is if they have no mass,
> >
> > They have no rest mass, but they can have relativistic mass at
> > the speed of light. Which essentially means that they can only exist by
> > going at the speed of light relative to everything.
> >
> >> how come we can detect them at all. The last thread was talking about
> >
> > They have mass when they move at the speed of light and only
> > then, because infinity times zero equals something indertiminate.
>
> Basic maths suggest that infinity times zero =1
> :-)
>
> (In case you didn't get that, try rearranging the formula One divided by
> Zero equals... <G>)

Now rearrange the formula 6.3587903028903821 / 0 = <lazy 8> and an
infinite number of other equations to conclude that it's inderterminate.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

On 12/02/2022 18:09, Ahem A Rivet's Shot wrote:
> On Sat, 12 Feb 2022 16:33:01 +0000
> "ChrisND@privacy.net" <chrisnd@privacy.net> wrote:
>
>> On 12/02/2022 15:51, Ahem A Rivet's Shot wrote:
>>> On Sat, 12 Feb 2022 14:19:48 -0000
>>> "Brian Gaff \(Sofa\)" <briang1@blueyonder.co.uk> wrote:
>>>
>>>> Yes heard that before, but the problem I have is if they have no mass,
>>>
>>> They have no rest mass, but they can have relativistic mass at
>>> the speed of light. Which essentially means that they can only exist by
>>> going at the speed of light relative to everything.
>>>
>>>> how come we can detect them at all. The last thread was talking about
>>>
>>> They have mass when they move at the speed of light and only
>>> then, because infinity times zero equals something indertiminate.
>>
>> Basic maths suggest that infinity times zero =1
>> :-)
>>
>> (In case you didn't get that, try rearranging the formula One divided by
>> Zero equals... <G>)
>
> Now rearrange the formula 6.3587903028903821 / 0 = <lazy 8> and an
> infinite number of other equations to conclude that it's inderterminate.

The basic problem being that there are an infinite number of infinities.

On Mon, 14 Feb 2022 00:23:58 +0000
Mike Fleming <mike@tauzero.co.uk> wrote:

> The basic problem being that there are an infinite number of infinities.

Indeed, but I'm not sure what order of infinity is needed to count
the infinities, neither was my pure maths supervisor when we covered the
transfinite integers.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

On 11/02/2022 09:56, Brian Gaff (Sofa) wrote:
> Yes especially since you will heat the atmosphere or in a vacuum you start
> to hit quantum effects that still means you cannot focus your beam properly.
> I often wonder where these ideas come from? Is it frustration about the
> speed of light or what?
> This speed of light thing seems to me to be a very curious thing.
> The limit is mainly put there by the effective mass of accelerating
> matter, and as photons are light, and have little mass, getting them to go
> faster would be difficult. It almost points to the universe having a
> processor whose speed is artificially governing the environment. If there
> really is a multiverse, might there be one with a different speed of light?
> Brian
>

Laser beams diverge pretty quickly. I found this out trying to level a
floor. It's about 1m per km. So presumably these lasers only work at
close range, unless you have a huge light sail.

There are many types of theoretical multiverse most of them are
completely untestable, unknowable, so you might just as well go to
church. There is a relatively good audiobook by Max Tegmark "Our
Mathematical Universe".

On 12/02/2022 16:33, ChrisND@privacy.net wrote:

>>     They have no rest mass, but they can have relativistic mass at the
>> speed of light. Which essentially means that they can only exist by
>> going at
>> the speed of light relative to everything.
>>
>>> how come we can detect them at all. The last thread was talking about
>>
>>     They have mass when they move at the speed of light and only then,
>> because infinity times zero equals something indertiminate.
>
> Basic maths suggest that infinity times zero =1
> :-)
>

In maths Measure Theory defines: countable infinity (aleph 0) times 0 =
0. (I never like that, but then I never really like infinity)

AIUI photons have momentum but not mass, relativistic or otherwise.

On Sat, 19 Feb 2022 11:15:32 +0000
Pancho <Pancho.Dontmaileme@outlook.com> wrote:

> Laser beams diverge pretty quickly. I found this out trying to level a
> floor. It's about 1m per km. So presumably these lasers only work at
> close range, unless you have a huge light sail.

Beam divergence is a function (inverse) of aperture size and
they're playing synthetic aperture games on a ten metre scale, you probably
had an aperture of about a millimetre. They'll get a *much* tighter beam.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

On 19/02/2022 11:47, Pancho wrote:
> On 12/02/2022 16:33, ChrisND@privacy.net wrote:
>
>>>     They have no rest mass, but they can have relativistic mass at the
>>> speed of light. Which essentially means that they can only exist by
>>> going at
>>> the speed of light relative to everything.
>>>
>>>> how come we can detect them at all. The last thread was talking about
>>>
>>>     They have mass when they move at the speed of light and only then,
>>> because infinity times zero equals something indertiminate.
>>
>> Basic maths suggest that infinity times zero =1
>> :-)
>>
>
> In maths Measure Theory defines: countable infinity (aleph 0) times 0 =
> 0. (I never like that, but then I never really like infinity)
>
> AIUI photons have momentum but not mass, relativistic or otherwise.
>
Hmmm... I have a long standing theory which explains the duality of
light and the 'missing' mass of the universe (aka dark matter). I will
probably arrange to have it published posthumously.*

Chris
*yes, seriously.
--
The Deuchars BBB#40 COFF#14
Yamaha XV750SE & Suzuki GS550t
http://www.Deuchars.org.uk

On 19/02/2022 16:41, ChrisND @UKRM wrote:
> On 19/02/2022 11:47, Pancho wrote:
>> On 12/02/2022 16:33, ChrisND@privacy.net wrote:
>>
>>>>     They have no rest mass, but they can have relativistic mass at the
>>>> speed of light. Which essentially means that they can only exist by
>>>> going at
>>>> the speed of light relative to everything.
>>>>
>>>>> how come we can detect them at all. The last thread was talking about
>>>>
>>>>     They have mass when they move at the speed of light and only then,
>>>> because infinity times zero equals something indertiminate.
>>>
>>> Basic maths suggest that infinity times zero =1
>>> :-)
>>>
>>
>> In maths Measure Theory defines: countable infinity (aleph 0) times 0
>> = 0. (I never like that, but then I never really like infinity)
>>
>> AIUI photons have momentum but not mass, relativistic or otherwise.
>>
> Hmmm...  I have a long standing theory which explains the duality of
> light and the 'missing' mass of the universe (aka dark matter).  I will
> probably arrange to have it published posthumously.*
>
> Chris
> *yes, seriously.

I have a th^h^h^h^an hypothesis too. Lots and lots and lots and lots of
free particles which haven't conglomerated into anything individually
detectable, floating//bouncing about/etc freely in the space between the
visible lumps, clumps and clouds.

--
Rusty Hinge
To err is human. To really foul things up requires a computer and the BOFH.

On 19/02/2022 12:27, Ahem A Rivet's Shot wrote:
> On Sat, 19 Feb 2022 11:15:32 +0000
> Pancho <Pancho.Dontmaileme@outlook.com> wrote:
>
>> Laser beams diverge pretty quickly. I found this out trying to level a
>> floor. It's about 1m per km. So presumably these lasers only work at
>> close range, unless you have a huge light sail.
>
> Beam divergence is a function (inverse) of aperture size and
> they're playing synthetic aperture games on a ten metre scale, you probably
> had an aperture of about a millimetre. They'll get a *much* tighter beam.
>

I suppose I should try and understand that, because I don't.

It seems to me that lots of little lasers focused to a small, distant
area would still lose power quickly. So to work you need not only a big
aperture, but a big target, but I could easily be wrong I'm not a physicist.

I actually came to the group after the storm, because I was wondering
about my poor old shed, that I maybe didn't treat quite as good as I
should have. You know, little things I should have said and done, I
just never took the time.

On 20/02/2022 09:02, Pancho wrote:
> On 19/02/2022 12:27, Ahem A Rivet's Shot wrote:
>> On Sat, 19 Feb 2022 11:15:32 +0000
>> Pancho <Pancho.Dontmaileme@outlook.com> wrote:
>>
>>> Laser beams diverge pretty quickly. I found this out trying to level a
>>> floor. It's about 1m per km. So presumably these lasers only work at
>>> close range, unless you have a huge light sail.
>>
>>     Beam divergence is a function (inverse) of aperture size and
>> they're playing synthetic aperture games on a ten metre scale, you
>> probably
>> had an aperture of about a millimetre. They'll get a *much* tighter beam.
>>
>
> I suppose I should try and understand that, because I don't.
>
> It seems to me that lots of little lasers focused to a small, distant
> area would still lose power quickly. So to work you need not only a big
> aperture, but a big target, but I could easily be wrong I'm not a
> physicist.
>
> I actually came to the group after the storm, because I was wondering
> about my poor old shed, that I maybe didn't treat quite as good as I
> should have.  You know, little things I should have said and done, I
> just never took the time.

Ah, this is the usual flypaper - physical Sheds. This group is
primarily. note, only primarily, concened with virtual sheds and what
gets put in them, grows in them, lives in them, or retreats to them.

Shall we say, it's a philosophical construction.

Excavated ♀sheep, you can usually find exactly what you want will fit in
neatly somewhere (if 'neatly' is allowed - this concept might be a step
too far for some Sheddi)

--
Rusty Hinge
To err is human. To really foul things up requires a computer and the BOFH.

Oh, and I forgot to say: Welcome to the Shed, Pancho.

--
Rusty Hinge
To err is human. To really foul things up requires a computer and the BOFH.

On Sun, 20 Feb 2022 09:02:19 +0000, Pancho
<Pancho.Dontmaileme@outlook.com> wrote:

>On 19/02/2022 12:27, Ahem A Rivet's Shot wrote:
>> On Sat, 19 Feb 2022 11:15:32 +0000
>> Pancho <Pancho.Dontmaileme@outlook.com> wrote:
>>
>>> Laser beams diverge pretty quickly. I found this out trying to level a
>>> floor. It's about 1m per km. So presumably these lasers only work at
>>> close range, unless you have a huge light sail.
>>
>> Beam divergence is a function (inverse) of aperture size and
>> they're playing synthetic aperture games on a ten metre scale, you probably
>> had an aperture of about a millimetre. They'll get a *much* tighter beam.
>>
>
>I suppose I should try and understand that, because I don't.
>
>It seems to me that lots of little lasers focused to a small, distant
>area would still lose power quickly. So to work you need not only a big
>aperture, but a big target, but I could easily be wrong I'm not a physicist.
>
>I actually came to the group after the storm, because I was wondering
>about my poor old shed, that I maybe didn't treat quite as good as I
>should have. You know, little things I should have said and done, I
>just never took the time.

Still, at least it was always on your mind.

I'm wondering about your shed: is it currently neatly distributed
amongst your neighbours' gardens or is it still up in the air
somewhere thinking "I've a feeling we're not in Kansas anymore."?

Nick

Pancho <Pancho.Dontmaileme@outlook.com> wrote in
news:sut02s$tvm$1@dont-email.me:

>
> I actually came to the group after the storm, because I was wondering
> about my poor old shed, that I maybe didn't treat quite as good as I
> should have. You know, little things I should have said and done, I
> just never took the time.

Did you snag your cardi on that nail? Never mind, sit on that half-bag of
blue circle and have a brown ale with us. We're an eccentric lot but you'll
catch up with our idiosyncrasies soon enough.

My PC is also called Sancho - Sancho Panza in full. It's just died - I
don't suppose you are the spirit of my PC become incarnate, are you? If so,
get back into that oblody box so I can stop using this flaptop.

--
Peter
-----

On Sun, 20 Feb 2022 09:02:19 +0000
Pancho <Pancho.Dontmaileme@outlook.com> wrote:

> On 19/02/2022 12:27, Ahem A Rivet's Shot wrote:
> > On Sat, 19 Feb 2022 11:15:32 +0000
> > Pancho <Pancho.Dontmaileme@outlook.com> wrote:
> >
> >> Laser beams diverge pretty quickly. I found this out trying to level a
> >> floor. It's about 1m per km. So presumably these lasers only work at
> >> close range, unless you have a huge light sail.
> >
> > Beam divergence is a function (inverse) of aperture size and
> > they're playing synthetic aperture games on a ten metre scale, you
> > probably had an aperture of about a millimetre. They'll get a *much*
> > tighter beam.
> >
>
> I suppose I should try and understand that, because I don't.

Synthetic aperture is weird.

> It seems to me that lots of little lasers focused to a small, distant
> area would still lose power quickly. So to work you need not only a big
> aperture, but a big target, but I could easily be wrong I'm not a
> physicist.

We used to have a real physicist in ye shedde - anyone seen Ivan ?

Anyway, if you just took a bunch of little lasers and pointed them
up at the sky you would indeed get a big beam that diverged just as much as
each individual laser.

The trick with synthetic aperture is to adjust the phase and
direction of each point so that the combined beam acts as though it was a
single distant point source being focussed by a ten metre parabolic lens -
*all* it takes is working out what the phase and direction would be at each
point if that were so and setting it up in real time at infrared
frequencies. On that scale and on those wavelengths there's either a very
rigid structure holding the lasers or some *really* fancy realtime vibration
compensation going on to pull it off - probably the latter.

There's a railway line near Madingley in Cambridgeshire where they
played that trick in reverse with radio telescopes back in the 1960s (the
one mile telescope) there's also the 5km telescope nearby which was built
later and has more tracks and dishes.

It's all about how the waves interfere once you get rid of the other
abberations.

> I actually came to the group after the storm, because I was wondering
> about my poor old shed, that I maybe didn't treat quite as good as I
> should have. You know, little things I should have said and done, I
> just never took the time.

Is it still there after the storm ? One of mine became airborne a
couple of storms ago and didn't take too well to the landing, it was really
only a temporary shelter though not a proper shed like the one that needs
roof repairs when the wind and rain stop for a bit (not this weak end).

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

Ahem A Rivet's Shot wrote:

> anyone seen Ivan ?

Not for agesnages.

On Sun, 20 Feb 2022 11:24:25 +0000
RustyHinge <rusty.hinge@foobar.girolle.co.uk> wrote:

> Oh, and I forgot to say: Welcome to the Shed, Pancho.

Yes indeed, and do mind your cardy on the nail ... oh never mind,
someone pass the sewing tin please.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

On 20/02/2022 13:31, Tease'n'Seize wrote:
> Ahem A Rivet's Shot wrote:
>
>> anyone seen Ivan ?
>
> Not for agesnages.

Nor I.

I do hope he's OK

--
Rusty Hinge
To err is human. To really foul things up requires a computer and the BOFH.

On 2022-02-20, Pancho <Pancho.Dontmaileme@outlook.com> wrote:
> On 19/02/2022 12:27, Ahem A Rivet's Shot wrote:
>> On Sat, 19 Feb 2022 11:15:32 +0000
>> Pancho <Pancho.Dontmaileme@outlook.com> wrote:
>>
>>> Laser beams diverge pretty quickly. I found this out trying to level a
>>> floor. It's about 1m per km. So presumably these lasers only work at
>>> close range, unless you have a huge light sail.
>>
>> Beam divergence is a function (inverse) of aperture size and
>> they're playing synthetic aperture games on a ten metre scale, you probably
>> had an aperture of about a millimetre. They'll get a *much* tighter beam.
>>
>
> I suppose I should try and understand that, because I don't.

That's one option. Another is to shrug and file it under "I'll take your
word for that." If more people did that the pandemic would already be over.

--
Bernard Peek
bap@shrdlu.com

In article <sutnfb$jlk$2@dont-email.me>, RustyHinge <rusty.hinge@foobar.
girolle.co.uk> on Sun, 20 Feb 2022 at 15:41:31 awoke Nicholas from his
slumbers and wrote
>On 20/02/2022 13:31, Tease'n'Seize wrote:
>> Ahem A Rivet's Shot wrote:
>>
>>> anyone seen Ivan ?
>>
>> Not for agesnages.
>
>Nor I.
>
>I do hope he's OK
>
He still appears to be a member of staff at Brunel University, at least
he is listed there, with (the same) e-mail address and building
location.

The last posting that I can find is on 28 July 2019. Earlier in the year
he was writing about cataracts and macular degeneration and previously I
think he had detached retinas. I dunno if this might have something to
do with it, or he just had enough of us old codgers. Not sure how old he
is, but when he posted a photograph of himself he look as if he
qualified for the epithet "old codger".
--
0sterc@tcher -

"Où sont les neiges d'antan?"