Happy new year 2015 !!!

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Amazing facts about space !

1. Neutron stars can spin at a rate of 600 rotations per second.

Neutron stars are one of the possible evolutionary end-points of high mass stars. They're born in a core-collapse supernova star explosion and subsequently rotate extremely rapidly as a consequence of their physics. Neutron stars can rotate up to 60 times per second after born. Under special circumstances, this rate can increase to more than 600 times per second.

2. All of space is completely silent.

Sound waves need a medium to travel through. Since there is no atmosphere in space, space will always be eerily silent.

You may be asking how astronauts can talk to each other in space. Lucky for them, radio waves can travel through space. No problem there, Houston.

3. There is an uncountable number of stars in the known universe.

We basically have no idea how many stars there are in the universe. Right now we use our estimate of how many stars there are in our own galaxy, the Milky Way. We then multiply that number by the best guesstimate of the number of galaxies in the universe. After all that math, NASA can only confidently say that say there all zillions of uncountable stars. A zillion is any uncountable amount.

An Australian National University study put their estimate at 70 sextillion. Put another way, that's 70,000 million million million. This figure is basically a guess, though.

4. The Apollo astronauts' footprints on the moon will probably stay there for at least 100 million years.

Since the moon doesn't have an atmosphere, there's no wind or water to erode or wash away the Apollo astronauts' mark on the moon. That means their footprints, roverprints, spaceship prints, and discarded materials will stay preserved on the moon for a very long time.

They won't stay on there forever, though. The moon still a dynamic environment. It's actually being constantly bombarded with "micrometeorites," which means that erosion is still happening on the moon, just very slowly.

5. 99% of our solar system's mass is the sun.

Our star, the Sun, is so dense that it accounts for a whopping 99% of our entire solar system. That's what it allows it to dominate it gravitationally. Technically, our Sun is a "G-type main-sequence star" which means that every second, it fuses approximately 600 million tons of hydrogen to helium. This means that it also converts about 4 million tons of matter to energy as a byproduct.

Being the type of star that the Sun is, it also means that when it dies, it will become a red giant and envelop the earth and everything on it. But don't worry: That won't happen for another 5 billion years.

6. More energy from the sun hits Earth every hour than the planet uses in a year.

You should be sad to know that solar technology produces less than one-tenth of 1% of global energy demand. This is due to several factors, including how much land is required for solar panels to capture enough energy for a population of people to use, how unreliable it is in bad weather and at night, and how expensive the technology is to install.

Despite all these drawbacks, the use of solar energy has increased at a rate of 20% each year for the past 15 years.

7. If two pieces of the same type of metal touch in space, they will bond and be permanently stuck together.

This amazing effect is called cold welding. It happens because the atoms of the individual pieces of metal have no way of knowing that they are different pieces of metal, so the lumps join together. This wouldn't happen on earth because there is air and water separating the pieces. The effect has a lot of implication for spacecraft construction and the future of metal-based construction in vacuums.

8. The largest asteroid ever recorded is a mammoth piece of space rock named Ceres.

The asteroid is almost 600 miles in diameter. It's by far the largest in the asteroid belt and accounts for a whole third of the belt's mass. The surface area is approximately equal to the land area of India or Argentina. It's so big, there's actually some debate over whether to refer to it as a dwarf planet instead of an asteroid, even if it has mostly asteroid-like qualities.

Ceres piques our interest specifically, as water in the form of ice has been spotted on its surface. An unmanned spacecraft named Dawn is due to be orbiting the space rock by 2015.

Modern Tests of Relativity

There seems to be an abundance of anti-relativity threads on this ( and all other ) science forums, so I thought it is about time to start a thread in support of relativity ! 
For this purpose I would like to present some modern day empirical tests of relativity - while everyone knows about the likes of Michelson-Morley etc ( being the classical tests ), there are many more modern empirical tests which are not as widely known. Here's a small sample :


Tests of Special Relativity & Relativity Principle

Cryogenic Optical Resonators : http://www.exphy.uni-duesseldorf.de/...prl78_4741.pdf
Non-Stationary Optical Cavities : http://www.exphy.uni-duesseldorf.de/...xiv0510169.pdf
Lorentz Invariance : Special relativity passes key test - physicsworld.com
Time Dilation in Satellites : http://www.quantum.physik.uni-mainz...._861(2007).pdf
Length Contraction in Heavy Ion Colliders : http://home.broadpark.no/~ccsernai/Csernai-textbook.pdf
Relativistic Lorentz Force Tests : The effects of the Aharonov-Bohm type as tests of the relativistic interpretation of electrodynamics
Anisotropy of Inertial Mass Tests : An Error Occurred Setting Your User Cookie
Time dilation in mu-mesons : Measurement of the Relativistic Time Dilation Using
Length contraction in free electron Lasers : What is SR, how is it generated and what are its properties?Length contraction in Penrose-Terrell Rotations : Can You See the Lorentz-Fitzgerald Contraction?
Penning Traps : Antimatter tests of Lorentz violation - Wikipedia, the free encyclopedia


Tests of General Relativity

Universality of Gravitational Red Shift : http://www.exphy.uni-duesseldorf.de/...2-PRL10401.pdf
Gravitational Potential at Short Distances : http://www.exphy.uni-duesseldorf.de/...2-PRL10401.pdf
Tests of Lorentz Invariance : http://relativity.livingreviews.org/...005-5Color.pdf
Gravitational Red Shift / Pound-Rebka : http://luth2.obspm.fr/IHP06/lectures...avRedshift.pdf
Light Deflection within the Solar System/Shapiro Delay : [astro-ph/0302294] The Measurement of the Light Deflection from Jupiter: Experimental Results
Lunar Laser Ranging to test Nordvedt Effect : Phys. Rev. 169, 1017 (1968): Equivalence Principle for Massive Bodies. II. Theory
Hafele-Keating Experiment for Time Dilation : Around-the-World Atomic Clocks: Predicted Relativistic Time Gains
Thirring-Lense Effect : http://www.nature.com/nature/journal...ture03007.html
Geodetic Effect : Phys. Rev. Lett. 106, 221101 (2011): Gravity Probe B: Final Results of a Space Experiment to Test General Relativity
Orbital Decay through Gravitational Waves in Binary Pulsar System PSR J-0737-3039 : Tests of General Relativity from Timing the Double Pulsar

Latest Results

Confirmation of "Maeder Effect" : http://physicsworld.com/cws/article/...during-eclipse
Pulsar in Relativistic Binary : http://www.sciencemag.org/content/340/6131/1233232
Gravity Probe B : http://einstein.stanford.edu


Needless to say all of these tests confirmed the predictions of the theory of relativity to varying, but very high degrees. No violations of any laws of relativity have ever been observed in empirical experiments, to the best of my knowledge, and more tests and experiments continue to be scheduled for the near future.
Also, one must consider quantum electrodynamics ( QED ), which is built on relativity from the ground up - again, needless to say that all QED effects are in perfect agreement with experiment. In fact, a large part of modern day electronics and technology is directly based on QED, and would not be functioning without it being correct !
Relativity works !!!