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calling all physicists



 
 
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  #11  
Old September 29th 17, 12:54 PM posted to uk.tech.digital-tv
Peter Crosland
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Default calling all physicists

On 29/09/2017 10:05, Jim Lesurf wrote:
In article , Bill Wright
wrote:
Apparently shock waves can travel trough the air at speeds exceeding
that or normal sounds. In that case, if an electromagnetic shock wave
was generated could it travel faster than the speed of light?


Short answer:

Cherenkov

Longer answer:

When I was still in the 'ed biz' and ocasionally wrote for New Scientist I
started getting told about all kinds of journal papers that - one way or
another - implied or claimed FTL. Other academics I knew also started
sending them to me as puzzle-pieces to spot the flaw(s). Sadly, they were
all flawed, hence the implications/claims were bollox. (Technical term
often used by academics.)

Later on I got sent a research council report to assess. This was a final
report on a project they'd given a grant. It was the work of a well known
prof who'd extracted a quarter of a million quid to make a system to try
out his ideas. They implied FTL. One of his co-workers had visited us and
given a talk on the project while it was under way. At the time I had my
doubts. The final results confirmed them. Very fancy complex maths and
loads of graphs and claims. Sadly, again, they were bollox. No idea if they
really believed what they'd written, and simply had made some daft errors,
or couldn't face admitting they'd made a mess and wasted the money.

Sound and light are very different. Beyond that, it drifts into the "it
depends what you mean by" areas when it comes to the speed of light.


I would suggests it also depends what you mean by a shock wave. I assume
Bill was talking about what is essentially a sound wave. Alternatively
if he meant the EMP then that is essentially an electro-magnetic wave
that cannot exceed the speed of light in identical conditions. Your term
for FTl is very apposite.


--
Peter Crosland

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  #12  
Old September 29th 17, 01:24 PM posted to uk.tech.digital-tv
MR
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Default calling all physicists

On Friday, 29 September 2017 07:41:28 UTC+1, Brian Gaff wrote:

However if your particle has no mass , then that would seem to me to make
its increase a little dubious.


Massless particles include photons, a particle of light (or any electromagnetic wave). These do indeed travel at light speed in a vacuum.
  #13  
Old September 29th 17, 02:16 PM posted to uk.tech.digital-tv
Jim Lesurf[_2_]
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Default calling all physicists

In article , MR
wrote:
On Friday, 29 September 2017 07:41:28 UTC+1, Brian Gaff wrote:


However if your particle has no mass , then that would seem to me to
make its increase a little dubious.


Massless particles include photons, a particle of light (or any
electromagnetic wave). These do indeed travel at light speed in a
vacuum.


More precisely, have no rest mass. They do have momentum and energy, and
thus mass in accord with Relativity.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm
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  #14  
Old September 29th 17, 02:25 PM posted to uk.tech.digital-tv
Jim Lesurf[_2_]
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Default calling all physicists

In article , Peter
Crosland wrote:
I would suggests it also depends what you mean by a shock wave. I assume
Bill was talking about what is essentially a sound wave. Alternatively
if he meant the EMP then that is essentially an electro-magnetic wave
that cannot exceed the speed of light in identical conditions. Your term
for FTl is very apposite.


TBH Relativity, etc, don't necessarily totally forbid FTL. What they
effectively seem to rule out is starting from rest and accellerating up to
FTL. (Or vice versa) because the values required 'blow up' as you go though
'c'.

However it may be that there are ways around this, or that
always-faster-than-light things exist. Relativity doesn't prove these can
exist. Just that as yet we've not seen a sign of it, and could then modify
our ideas.

What did dissapoint me, therefore, was that in paper after paper, any hint
was so easy to find flawed. I'd have *loved* someone to find a practical
way around the 'speed limit'. :-)

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm
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  #15  
Old September 29th 17, 04:30 PM posted to uk.tech.digital-tv
Brian Gaff
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Default calling all physicists

I reckon with some fairly basic research anyone could come up with the
fundamentals of building an H bomb, the trick is the engineering to allow
the hydrogen to stay around so you can use it in the fusion reaction before
the bomb shatters.

The only way to use atomic bombs is this way as it needs a less heavy
amount of fissionable material than that used in the last war, for example.
This is important if you are putting it on a rocket.

I noted the other day that one company will sell you an underwater stealth
drone to deliver your dirty bomb to coastal installations silently so all
navy vessels would be uninhabitable for years. I'm sure if you knew where
the nuclear subs were you could use it on those as well.

Brian

--
----- -
This newsgroup posting comes to you directly from...
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"Jim Lesurf" wrote in message
...
In article , R.
Mark Clayton wrote:
You can get the equivalent of the bullet with light: a particle which
moves faster than the speed of light in the medium (eg water) - but
not faster than "c", the speed in a vacuum. But I don't know of any
EM "shock" wave.


Electromagnetic pulse (from H bomb).


Not sure that is correct. A shock wave tends to depend on propagating in a
nonlinear medium, and alters the local behaviour to get a change in
propagation velocity. (e.g. in 'high' explosives).

EMP weapons would probably be detonated in space above the atmosphere to
get maximum coverage. The intent is to generate very large fields and
rates-of-onset, etc, to toast electronics as a result of the effects
produced. The wavefront probably would interact with the materials in the
atmosphere, but probably not change the velocity much. However if someone
has checkable figures, I'd be interested to see them. Trying to publish
them might get you shot, first, though. :-)

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics
https://www.st-andrews.ac.uk/~www_pa...o/electron.htm
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  #16  
Old September 29th 17, 05:13 PM posted to uk.tech.digital-tv
R. Mark Clayton[_2_]
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Default calling all physicists

On Friday, 29 September 2017 03:50:48 UTC+1, wrote:
Apparently shock waves can travel trough the air at speeds exceeding
that or normal sounds. In that case, if an electromagnetic shock wave
was generated could it travel faster than the speed of light?

Bill


There was a young lady called Bright
Who could travel faster then light
She set of one day
In a relative way
And came back the previous night!
  #17  
Old September 29th 17, 05:23 PM posted to uk.tech.digital-tv
Jim Lesurf[_2_]
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Posts: 4,228
Default calling all physicists

In article , Brian Gaff
wrote:
I reckon with some fairly basic research anyone could come up with the
fundamentals of building an H bomb, the trick is the engineering to
allow the hydrogen to stay around so you can use it in the fusion
reaction before the bomb shatters.


The 'trick' is the exceedingly high precision needed with the timing, etc.
In principle, easy. In practice, very hard to get right... fortunately.
Although, sadly, not as hard to do as we may come to wish.

I noted the other day that one company will sell you an underwater
stealth drone to deliver your dirty bomb to coastal installations
silently so all navy vessels would be uninhabitable for years. I'm sure
if you knew where the nuclear subs were you could use it on those as
well.


Yes, the eventual ubiquity of glider undersea drones flocking and using
satellite comms is likely to render our much-fabled 'trident replacement'
an insanely costly white elephant *long* before it even gets into service.
It will remain just political willie-waving, at our great expense.
Engineers know this, but politicians choose to ignore it because they want
SSNs to let them preen themselves on the UN Security Council, etc.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

  #18  
Old September 29th 17, 08:39 PM posted to uk.tech.digital-tv
Jeff Layman[_2_]
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Default calling all physicists

On 29/09/17 14:25, Jim Lesurf wrote:
In article , Peter
Crosland wrote:
I would suggests it also depends what you mean by a shock wave. I assume
Bill was talking about what is essentially a sound wave. Alternatively
if he meant the EMP then that is essentially an electro-magnetic wave
that cannot exceed the speed of light in identical conditions. Your term
for FTl is very apposite.


TBH Relativity, etc, don't necessarily totally forbid FTL. What they
effectively seem to rule out is starting from rest and accellerating up to
FTL. (Or vice versa) because the values required 'blow up' as you go though
'c'.

However it may be that there are ways around this, or that
always-faster-than-light things exist. Relativity doesn't prove these can
exist. Just that as yet we've not seen a sign of it, and could then modify
our ideas.


If they did exist, what do the theories say about them slowing down to
the speed of light or even less than it. Or would that not be possible?
And if they did slow down to less than c, would it then not be possible
for them to accelerate above it again?

--

Jeff
  #19  
Old September 29th 17, 11:46 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 2,095
Default calling all physicists

On 29/09/2017 14:16, Jim Lesurf wrote:

Massless particles include photons, a particle of light (or any
electromagnetic wave). These do indeed travel at light speed in a
vacuum.


More precisely, have no rest mass. They do have momentum and energy, and
thus mass in accord with Relativity.

Jim


Weirdly, a lot of this stuff starts to sound like the scientists modify
the theory to make it fit. A bit like Einstein did with his made up
cosmological constant, or like the warmists are doing like crazy these
days as it becomes more and more obvious that the observations don't fit
the computer models.

Funny business, science. It used to be like Caesar's wife, but now we
start to realise they're all just worried about grants and careers and
mortgages and reputations, like the rest of us.

Bill

  #20  
Old September 30th 17, 09:33 AM posted to uk.tech.digital-tv
Jim Lesurf[_2_]
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Posts: 4,228
Default calling all physicists

In article , Jeff Layman
wrote:
However it may be that there are ways around this, or that
always-faster-than-light things exist. Relativity doesn't prove these
can exist. Just that as yet we've not seen a sign of it, and could
then modify our ideas.


If they did exist, what do the theories say about them slowing down to
the speed of light or even less than it. Or would that not be possible?
And if they did slow down to less than c, would it then not be possible
for them to accelerate above it again?


Its assumed that the problem is the same as for STL. That the variables
like 'mass' and 'energy' go towards being infinite as you approach 'c' from
either above or below. Hence things divide into three categories.

1) Always STL

2) Always moving at 'c'

3) Always FTL

and we have no way to move something from category to another without some
kind of transformation of the type of item. e.g. bash an electron and
positron together to get two photons. (Category 1 - Category 2) Sadly,
this process loses information so can't be guaranteed to be perfectly
reversed in terms of the individual input particles and their specific
properties.

All we can say with confidence about this is that particle accellerators
have been getting small subatomic particles up to very close indeed to the
speed of light, and the behaviour we observe agrees with relativity. As
yet, no clear sign of any flaw in relativity in this respect.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

 




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