You were up earlier as you have been
delivering the paper to Mrs L. next door since Carol has a lame leg. You did
your forty minutes of exercises. Kim, Paul, Owen and Brennan called to wish
Carol a Happy Birthday – they tried yesterday but you were not home. The boys
sang Happy Birthday but Brennan added “Grandma and Papa” for good measure. It
was cute and everyone enjoys the boys’ enthusiasms. Kim and Paul also saw The
Imitation Game last night and enjoyed the film. Eventually you both will
head into Kenwood for a Potbelly’s lunch and if Carol is up to it a check on
clothes at Macy’s. Carol is sitting on the side of the bed reading and you,
recently out of the bath, are relaxing in your favorite black-leathered bedroom
chair. – Amorella
1234 hours. Kim also said she has another part time job
until summer session at Kenyon College. One of her old friends and colleagues
is director at Kenyon and needs someone part time. Kim is eager to see how it
is working with students at a small college/university. It is an hour’s drive
each way from Delaware and she will be working on Wednesdays and Fridays. I am
happy and ever proud of her.
1321 hours. Reading BBC a few minutes ago I came upon this
‘who would have thought’ article. I have never heard of anyone wanting to slow
down light. Now it sounds quite intriguing, especially since it is possible.
What a time to be alive and able to pick up the science news so quickly. Some
of science comes to not or should I say ‘knot’ but what it does for the
imagination is something else again. How could anyone ever grow bored living
with a computer and the web on board. Life is something else. Even the precursor
to life (physics) is something else again. Bill Bryson’s A Short History of
Nearly Everything reminds me how little we know about our physical selves –
our cells, our DNA – I still can’t comprehend how we are even here let alone
where here is.
** **
22 January
2015 Last updated
at 20:28 ET
Scientists
slow the speed of light
By Kenneth
Macdonald
BBC Scotland Science Correspondent
A team of
Scottish scientists has made light travel slower than the speed of light.
They sent
photons - individual particles of light - through a special mask. It changed
the photons' shape - and slowed them to less than light speed.
The photons
remained travelling at the lower speed even when they returned to free space.
The
experiment is likely to alter how science looks at light.
The
collaborators - from Glasgow and Heriot-Watt universities - are members of the
Scottish Universities Physics Alliance. They have published their results in
the journal Science Express.
The speed of
light is regarded as an absolute. It is 186,282 miles per second in free space.
Light
propagates more slowly when passing through materials like water or glass but
goes back to its higher velocity as soon as it returns to free space again.
Or at least
it did until now.
Two and a
half years ago, the experimenters set out to see if they could slow down light
just a little - and keep it moving more slowly.
In a
laboratory at Glasgow university, Dr Jacquiline Romero, Dr Daniel Giovannini and
colleagues built what amounts to a racetrack for photons, the individual
particles of light.
Photon race
Then they
raced them in pairs. One photon they left in its normal state. The other photon
was sent through a special mask.
The mask
forced the photon to change its shape and travel slower than the speed of
light.
Dr Romero
explains: "After the mask, the photon is launched into a sort of racetrack
about a metre in length.
"Then
we take the time in which the unshaped photon finishes the racetrack, and the
shaped photon's time as well, and then compare the two times."
If they had
both been travelling at the speed of light it would have been a dead heat. But
the re-shaped photon came in second.
Not by much
- a few millionths of a metre - but it showed that it had not just been slowed
by the mask, but had continued to travel at less than light speed even after it
had returned to free space.
Light
travelling at less than the speed of light. Whose bright idea was that?
It grew from
a conversation between Prof Daniele Faccio at Heriot-Watt University and Prof
Miles Padgett at Glasgow.
Prof Padgett
says the crucial component is the mask - a software controlled liquid crystal
device: "That mask looks a little bit like a bull's-eye target.
"And
that mask patterns the light beam, and we show that it's the patterning of the
light beam that slows it down.
"But
once that pattern has been imposed - even now the light is no longer in the
mask, it's just propagating in free space - the speed is still slow."
But hang on
a minute. If a photon is a particle, how is it possible to impose a pattern on
it?
It's because
photons exist in the exotic and rather wonderful quantum realm, where the rules
of the reassuringly solid world in which we live tend to lose their grip.
They exhibit
what physicists call "wave-particle duality": they behave like both a
wave and a particle. So you can send them round a racetrack two by two like
particles, yet change the shape of one of them as if it was a wave.
Peloton
Complicated?
Oh yes. Which is why the researchers say it might help to think of a bicycle
race.
The peloton - the main bunch of riders - may be moving at a
constant speed. But within the bunch an individual rider may moving more
slowly, dropping back for a rest or a drink.
The bunch is
a beam of light, travelling at - yes - the speed of light. The riders are
photons, travelling at their individual speeds.
For Dr
Giovannini it's been a satisfying intellectual and experimental challenge:
"It mostly comes from a question we asked ourselves two and a half years
ago. We just kept working on it.
"It's
really, really interesting. It's just one of those big, fundamental questions
you may want to ask yourself at some point in the pub one night.
"And if
you follow through and you actually measure it it's quite amazing, isn't
it?"
Prof Padgett
says: "What makes our experiment different, and what has brought clarity
to this, is that rather than looking at a light pulse which contains many,
many, many photons we've reduced the experiment down to a single photon.
"So we
measure the speed of a single photon as it propagates.
"And we
find it's actually being slowed below the speed of light."
There are
some practical implications. Light is used to make extremely precise
measurements such as how far the Moon is from Earth.
The good
news is that we are not in for any nasty surprises on that scale. But
researchers using large aperture lenses to accurately measure very short
distances may be forced to take a second look for tardy photons.
Beyond that,
Dr Giovannini says practical, everyday uses for the discovery are possible.
Although he concedes the physics is more fundamental than applied right now.
"But,"
he says, "who knows?"
Selected and
edited from BBC
Post. - Amorella
Mid-afternoon.
You had Potbelly’s and listened to the live singer whom you like but Carol
decided she wasn’t ready to shop because of her leg, which is slowly getting
better. On the way home you decided to stop at Barnes and Noble. Just off the
I-71 ramp is a new Potbelly’s so now you won’t have to go all the way into
Kenwood. You were both pleasantly surprised. – Amorella
1519 hours. I will miss listening to the young singer. I
like her. Today she had a suitor/boyfriend who helped her load her speakers.
Very nice. Good for her and him too.
Doug responded to the BBC article on slowing
light. You think it is a great and even more so, an important question. - Amorella
** **
Dick, Amazing experiment.
Thanks for sharing. If we can slow down light in a lab what is the possibility
that nature can do it in the universe? What would it mean to our observations?
Doug
** **
Doug thinks like the scientist he is. Here’s
a question from your perspective. If one can discover a way to slow
light down and use this in a ship, would it then be easier to go faster than
the speed of light (slowed down) and thus still go almost as fast as the speed
of light? – Amorella
1637 hours. Home. I like thinking like a scientist, i.e. Doug,
but obviously I don’t always. Doug helps keep me honest. If the speed of light
is not always a constant, then our calculations on distance would not be
accurate. And, if the speed is not constant would it then be possible for the
speed of light to be even faster? For
most intents and purposes we could still hold to the proposition that the speed
of light is 186,282.397 miles per second.
Carol is catching up on one of her shows.
Let’s go to Grandma Seven. – Amorella
Dusk
is gone. You have been reworking Grandma Seven from the original Running
Through. We will have it narrowed down and re-arrange the cemetery setting.
Later. Post. - Amorella
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