
The Case of the 5-Millisecond Cosmic Radio Burst (2014) - kposehn
http://www.planetary.org/blogs/guest-blogs/2014/0514-the-case-of-the-5-millisecond-cosmic-radio-burst.html
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bladedtoys
While calling the bursts FRB is certainly descriptive, I kind of miss the
whimsy of names like LGM [0]

[http://en.wikipedia.org/wiki/PSR_B1919%2B21](http://en.wikipedia.org/wiki/PSR_B1919%2B21)

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TheOtherHobbes
See also:

[http://arxiv.org/pdf/1503.05245v2.pdf](http://arxiv.org/pdf/1503.05245v2.pdf)

which suggests the FRB dispersions are quantised to a standard unit. A lot of
newsies picked this up last week and suggested it was proof of... something
unusual.

The authors think it suggests the opposite.

Given the date, I can't tell if the paper is serious or not. But if it's meant
to be serious, the effect seems real - possibly an artefact of a very small
sample size, but it's hard to tell.

It would be useful to have access to the raw data to see the exact dispersion
shape and frequency range, to check whether it matches - say - any standard
radar chirp signal.

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ghshephard
re: " If the star is above that critical mass but spinning, the centrifugal
force can help keep the star from collapsing right away"

I still resent my Grade 11/12 physics teacher for insisting that there was no
such thing as centrifugal force, and that what was really occurring was
centripetal acceleration only. He basically decided that newtons third law
would not exist in his classroom.

~~~
xahrepap
My physics teacher did the same thing. When it came down to it, he was talking
about vocabulary, not science. The definition of "force" he was trying to get
across meant that there was no such thing as "centrifugal force".

~~~
ghshephard
Yeah, I get that he was teaching out of a book that told him (and probably
every science teacher in existence) to teach this way - it just never made any
sense. Anybody who has ever ridden a tilt-a-whirl instinctively _knows_ there
is a force pushing you _out_ (otherwise you would go falling to the ground
when it went vertical).

Why science instructors are so focussed on the inwards force (in the case of a
tilt-a-whirl, it's the outer frame, in the case of orbiting a planet/spinning
neutron star, it's gravity) to the exclusion of everything else never made any
sense to me, and caused me know end of distress.

It probably came from the same place that suggested a charged item can attract
a neutral object, but that a neutral object cannot attract a charged item.
That made even _less_ sense to me, but was right out of the book.

Needless to say, my high school physics instructor and I never really got
along very well.

~~~
aptwebapps
If you tell someone there's no such thing as a centrifugal force and that (in
rotation) there's only the centripetal force, you're half wrong. There's also
ordinary inertia which is what is pushing you against the side of the tilt-a-
whirl.

Telling someone there's no such thing as the centrifugal force in physics is a
good starting point but you shouldn't stop there.

~~~
tjradcliffe
> Telling someone there's no such thing as the centrifugal force in physics is
> a good starting point but you shouldn't stop there.

No, it's a terrible starting point. Maybe the worst possible starting point.
"Here is something you know to be true that I am going to tell yo is false,
creating confusion and a tendency to reject anything else I say as obvious
nonsense."

 _End_ with the notion of fictitious forces (which do exist, so the name is
terrible), don't start with them, unless you want to be like one of those
dreadful people who talks about negative generalized temperature or negative
generalized resistance to neophytes without first explaining the
generalization, so you deliberately mislead people into thinking you are
talking about the familiar, ungeneralized concept.

There is no evidence whatsoever that such introductions make anyone more
motivated or able to understand, and a good deal of reason to expect they
don't.

~~~
ghshephard
Thanks very much - I think you are nailing it exactly. My physics instructor
just blatantly said, "Centrifugal force - it's fiction. Doesn't exist.
Centripetal acceleration does exist." He pretty much left it at that, so I
tended to ignore everything else he said for the next couple years that didn't
make sense to me, thought he didn't know what he was talking about.

I've probably learned more about the topic from this HN thread than I ever did
in grade 11 physics.

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fullwedgewhale
Just in time for the X-Files coming back this summer!

