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Planck Temperatures

I’ve read of some incredibly large temperatures that emenate from stars. Many in the millions of degrees. How accurate are these claims,how do they tell the difference between say…9 million degrees and 9.5 million ? Is is done by measuring the brightness of the source along with distance and would not the fuel itself affect the brightness? I’ve heard that the big bang generated temps in the trillion degree range. How can that be measured or even assumed to be factual. Is it guesswork or is there proof ? There seems to be a physical limit to negative temperatures yet no limit for positive temps. Is that because all atomic activity stops @ -460 f ? I wonder too why no upper limt as I would think any and all (fuel) used to heat those high temps would disappear at some point.
Noviceily yours;
Craig
When I was told to question everything, I asked why.

Parallax Method

Can you please explain about paralax method?

How to use it to calculate the distance between two astronomical objects?

Asked Shivangi

Answer:

Parallax  is the change in the apparent position of an object due to change iv view point.

Read more here

The parallax method is a way of measuring distances of far-away objects.

Read more: http://wiki.answers.com/Q/What_is_the_parallax_method#ixzz21XoSSONi

Parallax Method to determine the distance of stars

WHAT IS THE WAY TO MEASURE THE DISTANCE OF DISTANT OBJECTS LIKE STARS WITH THE HELP OF PARALLAX METHOD

SHWETANSU asked.

Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.

Astronomers use the principle of parallax to measure distances to celestial objects including to the Moon, the Sun, and to stars beyond the Solar System.

See the animation below to understand the parallax method for determining the stellar distances

Find more information here

http://spiff.rit.edu/classes/phys240/lectures/parallax/parallax.html

 

Aswin Ramesh Asked (via email)
is it the same method that we use in trigonometry ?
 Answer:
Parallax is a different concept, though we are using the principle of trigonometry to solve problems based on it.

Questions from Relativity

Sam asks

  1. “After the Sun, the nearest star visible to the naked eye is Rigel Centaurus, which is 4.35 light years away. If a Spacecraft was sent there from earth at a speed of 0.80c, how many years would it take to reach that star from earth as measured by observers (a) On Earth; (b) On the Spacecraft? (c) What is the distance travelled according to observers on the spacecraft?”
  2. A beam of a certain type of elementary particle travels at a speed of 2.58 x10^8 m/s. At this speed, the average lifetime is measured to be 2.50 x 10^-8 s. What is the particles lifetime at rest?
  3. Imagine a rocketship takes off for a distant planet and can travel at many times the speed of light. (We know that this is impossible but let’s just say you can for this question). Observers on the planet are viewing the incoming spaceship through a powerful telescope. Describe what they will see from the moment the rocketship leaves Earth until it land on the observer’s planet. Support your answer with example equations.
  4. If you were on a rocketship travelling at 0.6c away from the sun, at what speed would the sunlight pass you?
  5. A 100 MeV electron, travelling at 0.999987c, moves along the axis of an evacuated tube that has a length of 3.00m as measured by a laboratory observer S with respect to whom the tube is at rest. An Observer S0 moving with the electron, however, would see this tube moving past her. What length would the tube appear to the Observer?


Formation of Heavier Elements

H. Manishankar (KV Pattom) Asked

Question: Iron is the heaviest element that can be formed by nuclear reactions in a star.So how the heavier elements after iron were formed?And could there be further heavier elements out there in the cosmos?

Answer:

Nuclear fusion inside a star is not the only process my which new elements are created. There are many others too.

During a supernova explosion many unpredictable nuclear transmutations occur, fusing elements and forming heavier elements.

But however, the amount of elements heavier than iron is less.

It’s a good idea to think back (say from the time of BigBang)

Every explosion has a consequent implosion resulting in creation of heavier elements

Remember that birth and death of stars are taking place everyday in some part or other of the universe. The earlier stars had relatively lighter elements in their core. As they die, the remains form part of other stars and other celestial bodies thereby forming heavier elements in the universe.

(I don’t claim that this is a complete answer. Visitors are requested to suggest amendments to this Answer via comments)

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Schrodinger’s Cat in Daily Life

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