Team-BHP - The Astronomy Thread: FAQs, News & Trivia

Quote:

Originally Posted by alpha1 (Post 3706270)

1. Speed of light (or any electromagnetic radiation) is constant because it is not a physical wave requiring a medium. The basis of EM radiation is that there is a changing magnetic field which creates an electric field, and if this electric field also changes with time (which it does), it creates a magnetic field, ... ad infinitum. This is the essence of Maxwell's equations. And this what leads to propagation. The propagation of this field happens at the "speed of light". The only thing that affects this propagation speed is the electrical (permittivity) and magnetic (permeability) properties of material through which these travel.

Hence, there is no reference frame requirement for measuring the "speed of light". All EM waves always travel around in the speed determined according to the Maxwell's equations.

2. We assume X+Y because we (1) observe this to happen in our practical lives (2) Newton's laws lead to this result. (Newton's laws also came about to explain all that we were coming across and observing in the 17th century)

Quote:

Originally Posted by alpha1 (Post 3706623)

Sorry, but actually I jumped on the point no1 :D
I just tried thinking yesterday after my post: why would someone assume that light should also go X+Y, and I got my answer perhaps this was also what was going in your mind:
People believe that light comprises of some particles. So the expectation is that the light particle jump off the moving platform and thereby achieve a greater velocity.

But we have experimental results to show that light/EM is actually a wave (yes, it is wave-particle duality - but these particles are not exactly like mechanical slug balls, so let me continue calling them waves).
A wave always propagates at speeds governed by the media properties (elasticity and density), and has no relevance to the source's speed. (This is why we have doppler's effect)

Now the only objection to this is the point that a mechanical wave relies upon a medium. A medium might be moving itself. Therefore the speed of such mechanical waves might change with the frame of reference.
Maxwell's equation led to results that EM waves do not require any medium. Therefore all the light, everywhere has to have same speed.

So there are two things:
1. Light is a wave, and therefore speed depends on medium properties
2. Light is a special wave, and therefore does not even require the presence of a medium!

Now expanding upon this concept, we must also understand that every "reality" that we experience is based on information. And that information is always based on EM radiation.

Hello alpha1, both your above posts are very interesting and informative. I just felt that perhaps a slight digression on the newer ideas being discussed over the past few decades might also prove interesting.
The dual nature of EM propagation (wave/particle) is being increasingly resorted to in explaining various phenomena (quantum physics, polarization, diffraction & lasers among other phenomena). Also the idea that light velocity is a constant across frames of reference appears to be increasingly challenged in theoretical physics. Prof E.C.G. Sudarshan (TIFR, Harvard, Univ.of Texas, etc) had proposed the existence of faster-than-light particles - tachyons - as far back as the sixties. The nature and size of the universe has always been of interest to me and there is still no agreement between the two prevalent schools of thought - the "steady state" and the "big bang" theories. Being an Indian and more familiar with our own way of thinking, the steady state theory appeals more to me - in essence that the universe has always been there and always will be! The law of conservation being served with the idea of "black holes" being all-consuming and "white holes" or "cosmic gushers" spewing it all out somewhere & somewhen!

Quote:

Originally Posted by shashanka (Post 3902218)

1. The dual nature of EM propagation (wave/particle) is being increasingly resorted to in explaining various phenomena (quantum physics, polarization, diffraction & lasers among other phenomena).

2. Also the idea that light velocity is a constant across frames of reference appears to be increasingly challenged in theoretical physics. Prof E.C.G. Sudarshan (TIFR, Harvard, Univ.of Texas, etc) had proposed the existence of faster-than-light particles - tachyons - as far back as the sixties.

3. The nature and size of the universe has always been of interest to me and there is still no agreement between the two prevalent schools of thought - the "steady state" and the "big bang" theories. Being an Indian and more familiar with our own way of thinking, the steady state theory appeals more to me - in essence that the universe has always been there and always will be! The law of conservation being served with the idea of "black holes" being all-consuming and "white holes" or "cosmic gushers" spewing it all out somewhere & somewhen!

1. Agreed. The Wave particle duality has been in place since the discovery of the Photoelectric effect and Black body radiation paradox. The only reason why I chose to reject particle theory and project the wave theory was to talk about Maxwell's electromagnetism. And the point to be noted, "your honor" :D: is that in the wave particle duality, photon are not the corpuscles that Newton dreamt of or what we imagine a particle to be.

2. Yes, but if you recall even Einstein's theories remained theories till they were verified with observations. Like Mercury's orbit anomaly.

3. As of now, it has been verified that the universe is indeed expanding. I am afraid Mr. Hoyle as well as our ancient texts (and the elders writing those) were not correct on this.

Quote:

Originally Posted by alpha1 (Post 3902982)

Hi alpha1,

I accept that both Newton and Einstein were right in their own lifetimes. And equally likely is the possibility that (like Newton's classical physics) some of Einstein's remarkable insights may reveal their shortcomings in the times to come. The phenomena of non-locality in quantum mechanics and quantum pseudo-telepathy in game theory are peculiar off-shoots of this field. But since these are not astronomical phenomena perhaps they should be discussed elsewhere!

A recent astronomical breakthrough appears to be the Santilli telescope (see earthfiles.com website, as well as www.prweb.com/releases/2016/01/prweb13168382.htm) which uses a concave lens instead of the more conventional convex lens. The Santilli telescope detects what is described as "anti-matter" light sources which are invisible to conventional optical telescopes. Dr.Santilli (who was once nominated for a Nobel, no less!) demonstrated that with this telescope one can see Invisible Terrestrial Entities (ITE types 1 & 2) which appear to be intelligently controlled! This phenomena (described in the January 20, 2016 edition of the American Journal of Modern Physics) I find very interesting since the subject of UFOs & the possibility of alien intelligence has fascinated me for many years.

Quote:

Originally Posted by shashanka;3907014
A recent astronomical breakthrough appears to be the Santilli telescope (see earthfiles.com website, as well as [URL="http://www.prweb.com/releases/2016/01/prweb13168382.htm"

www.prweb.com/releases/2016/01/prweb13168382.htm[/url]) which uses a concave lens instead of the more conventional convex lens. The Santilli telescope detects what is described as "anti-matter" light sources which are invisible to conventional optical telescopes. Dr.Santilli (who was once nominated for a Nobel, no less!) demonstrated that with this telescope one can see Invisible Terrestrial Entities (ITE types 1 & 2) which appear to be intelligently controlled! This phenomena (described in the January 20, 2016 edition of the American Journal of Modern Physics) I find very interesting since the subject of UFOs & the possibility of alien intelligence has fascinated me for many years.

http://www.thunder-energies.com/docs...r-12-15-15.pdf
http://article.sciencepublishinggrou...5040101.17.pdf

So the thing that comes out is this:
1. there are CMOS image developed on the camera
2. the images are result of focusing
3. the focusing of the image has been achieved by using concave lens
4. thus it mean that the glass is acting like a negative refractive index material for this unique "light" that is coming from a unique material

If the light from antimatter is that different, how is it being captured by our (matter) world CMOS and CCD sensors?

Quote:

Originally Posted by alpha1 (Post 3909658)

"Unique light" and "Unique material" is not really something I can comment on, since I don't have a Ph.D. in theoretical physics like Dr. Santilli:D. But one thing I am certainly looking forward to is the reaction of the establishment to this new development from Dr.Santilli. As you may have gathered (if you have followed the threads on the Santilli telescope & the thunder-energies eulogies of Dr.Santilli!) this gentleman has been at loggerheads with the scientific establishment for a long time, which makes him an underdog in my book! And to be honest, I have a soft spot for all underdogs - in the academic sphere and elsewhere. I shall be following developments closely!

Another interesting breaking news in astrophysics is the first time that - "a binary black hole merger has been observed and this is also a story about the detection of gravitational waves for the first time” - David Reitze, LIGO Ex. Dir. (Caltech), LIGO Press Conference, February 11, 2016.

The article (in www.earthfiles.com) goes on to say that 100 years after Dr. Einstein's prediction "that acceleration of massive objects should generate gravitational waves, distortions in spacetime radiating outward at the speed of light", the MIT and Caltech Laser Interferometer Gravitational-Wave Observatory (LIGO) research now confirms it has detected gravitational waves where two black holes are spiraling into each other and merging.

Interesting times indeed! It is now only a matter of time perhaps, that the existence of "worm holes" in space is established. And from there it may be just another step to the time travel phenomena that is so beloved of SF writers!

The following news snippets appeared recently in Linda Howe's 'Earthfiles' (https://www.earthfiles.com/) and might be of interest in this thread:

1) Interstellar Travel with Light Propulsion. Report Upcoming.
“Much as wind pushes a sail, there's a way to be propelled by light or photons.”
- Philip Lubin, Ph.D., Prof. of Physics, Univ. of Calif.-Santa Barbara

Illustration of laser photons propelling a small “wafer-scale”
droid spacecraft at 25% the speed of light. Light moves
at 186,000 miles a second in this universe. 25% light speed could
push an unmanned small droid to our closest star, Alpha Centauri,
4.5 light-years from Earth, in about 17 years. Illustration
by Q. Zhang, UCSB Experimental Cosmology Group.

2) Old Nuclear-Powered Satellites Orbit Earth with Plutonium Onboard.
One Crash Could Contaminate Thousands of Square Miles.
Report upcoming.
“A lot of these satellites were for military purposes, for surveillance, for both
the U. S. and Soviet Union. We used plutonium, the most toxic radioactive substance.”
- Karl Grossman, Prof. of Journalism, SUNY-Old Westbury, NY

3) March 22, 2016 - Exploding Star “Seen” by Kepler Telescope.
For the first time on Earth, the visible light of an exploding star's shockwave has been captured by NASA's Kepler space telescope. The supernovae Type II explosion showing hydrogen occurred in a massive red supergiant, KSN 2011d, that was 500 times the size of our sun and 1.2 billion light-years away. NASA reports, “The shock breakout itself lasts only about 20 minutes, so catching the flash of energy is an investigative milestone for astronomers.”

Illustration of the 20 minutes that the “finger-like plasma jets
rush upward through the huge star's layers.” The shockwave reached
KSN 2011d's surface and exploded the whole star in a supernovae Type II
that NASA's Kepler Space Telescope recorded as “photometric observations.”
See video animation by NASA Ames, STSci/G. Bacon.

Wow! I did not expect to find an Astronomy/Astrophysics thread on teambhp. Its amazing how alongside cars we can share our other interests on the same forum. I am an astrophysics student myself. Subscribed!

Quote:

Originally Posted by Gany (Post 3898654)

I am planning to buy a telescope, refractor type. Any suggestion from the group, which is better, cost & where to buy. I do not want to buy a very expensive one & should be able to see planets, Saturn rings and if possible Orion Nebula:)

Here is photograph I clicked at Panambur beach sometime ago. Hand held on Nikon Coolpix S9700/30x

What is your budget range? Celestron offers some good quality beginner telescopes. It completely depends on what you are looking for. I personally have been using the Celestron 76mm Firscope for quite a bit now and I would say it is a great way to start your astronomical journey. It offers a good balance between price and use. You can observe the details of the moon clearly.

Orion telescopes are good as well but tend to be on the expensive side. A good telescope to observe Saturn's rings and Jupiter would be the 130EQ Astromaster. It is however a reflector type unlike the refractor you are looking for.

You definitely want to go for a fully manual telescope in order to keep the price down. Your best bet would probably be the Astromaster 114 EQ. Refractor, focal length of a 1000mm and light gathering power of 265x. The best part is, you get all this under 15k.

I will be very happy to answer any more questions regarding which telescopes to buy. All you need to decide is a budget range - apart from that, the sky is the limit.

As for where to buy the telescope, I have no idea as I live in the UK. Several websites like Amazon India and Flipkart list these items but I am not sure about their authenticity or service experience.