View Single Post
  #2  
Old December 11th 16, 04:57 PM posted to sci.astro
Mike Dworetsky
external usenet poster
 
Posts: 715
Default 1) the negative paraxes...

wrote:
..from the topic ''Letter to a friend ''
.. the negative parallaxes are a big mistery , as i told many times
.. almost nobody want to speak about it , and almost all don't know
its existence


Assuming you are talking about entries in a parallax catalogue or list, any
astronomer should know why there are negative parallaxes in the list.

.. Eistein and de Sitter could not imagine a similar thing
.. not only , untill the years 2000 nobody had suspected that
existence


Definitely an incorrect statement. Negative parallaxes have been known
about for more than a century.

.. so difficult to understand ! but exactly the half of not near
bodies ( stars , galaxies , quasars..) have a negative parallaxes ..


Your suspicion is correct. If you have a list of parallaxes of very distant
objects, so that their parallaxes are on average much smaller than your
limit of detection, then the errors of parallax are distributed normally,
with a bell-shaped curve plotting the likely distribution of values around a
mean of nearly zero. Hence we expect there to be approximately half of
those published parallaxes with values less than zero and half with values
more.

and you must make alone all the mental paths around its .. no books ,
no profs ,no magicians ...: i can only say my opinions ..and discuss
with you that opinions , trying togheter a reasonable street where
nobody walked .. ( i think that the negative parallaxes ' solution
can influence directly the dark matter and the age of universe )


This sounds a bit mystical. All that is happening is that very distant
objects have parallaxes so small that they cannot be determined with
accuracy, so half are going to be negative and half positive.

.. main asks and next program : 1) what is a parallax and a negative
parallax? 2) how a negative parallax can enter in our science?


If we rejected any measured result with a negative parallax, then we would
decide that the average of the positive values was real, hence we would
deduce that these very distant objects were actually a lot closer than they
really were. This would be a very bad mistake.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

Ads