Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Chapt17 Telescope experiments as distance tool #1574 ATOM TOTALITY
5th ed

Replies: 19   Last Post: May 24, 2013 7:25 PM

 Search Thread: Advanced Search

 Messages: [ Previous | Next ]
 plutonium.archimedes@gmail.com Posts: 18,572 Registered: 3/31/08
1604 Kepler's supernova Chapt17 Telescope experiments as distance
tool #1588 ATOM TOTALITY 5th ed

Posted: May 24, 2013 7:25 PM
 Plain Text Reply

On May 18, 4:37 pm, Brad Guth <bradg...@gmail.com> wrote:
(snipped)
>
> Your interpretation that 400 million light years is the optical limit
> of seeing other more distant stuff is perhaps not taking into account
> those extremely long time exposures of extremely sensitive CCDs
> gathering photons and thousands of frame stacking methods applied.

Well thanks for keep pushing me to make more clear.

One of the nasty problems of astronomy is a blizzard of terms for
which seem like appropriate but not actually the concept involved. For
example astronomy has these terms:

intensity

brightness

magnitude

luminosity

coherence

etc etc

What I am after, is the concept that says that light turned on at
distance x, can only travel so far before it is too attenuated that it
cannot be seen anymore. Even a supernova that goes off, has a distance
limit to where it is no longer able to be seen.

So let me put out an analogy. A shotgun with its thousand pellets. As
you shoot the gun the pellets are together closely and as they travel
meters they start to widen out and not so together and nearby. With
increasing distance of travel there is only 3 pellets per cubic meter.
With further distance, there is 1 pellet per cubic meter.

Light from a star, from a galaxy, from a supernova is much the same as
those pellets of a shotgun. At some distance, there are so few light
waves of that star, or galaxy or supernova so that the observer can no
longer see the object. I believe this upper limit is 400 million light
years, whereas astronomers mostly believe it is infinity.

Now I am looking at some old supernovae in human history-- such as the
1604 Kepler's supernova which was 20,000 (alleged) light years away.
So comparing the light of that supernova with its distance we can sort
of arrive at a upper limit of light travelling before a supernova is
no longer able to be seen due to sheer distance.

--
More than 90 percent of AP's posts are missing in the Google
newsgroups author search archive from May 2012 to May 2013. Drexel
University's Math Forum has done a far better job and many of those
missing Google posts can be seen here:

http://mathforum.org/kb/profile.jspa?userID=499986

Archimedes Plutonium
http://www.iw.net/~a_plutonium
whole entire Universe is just one big atom
where dots of the electron-dot-cloud are galaxies

© The Math Forum at NCTM 1994-2018. All Rights Reserved.