Fundamental Physical Constants
Coefficients of Friction
Indices Of Refraction
Nuclear & Particle Data
Special Math Constants
Calculators & Apps
Periodic Table of Elements
Time Reference & Exact Time
Humidex & Windchill Calculator
Decimal Multiples & Prefixes
Materials Safety Info
Nobel Prize & Bruce Medal Info
Electricity & Magnetism
Waves in Matter, Sound
Light, Optics and Photonics
Atomic & Nuclear
Special & General Relativity
Astronomy & Astrophysics
Definitions & Reference
All Answers, all categories
University and College Departments
Institutes and National Labs
History of Physics
Reference for Educators
Cartoons by Rick London
Cartoons by Mark Parisi
Cartoons by John McPherson
Cartoons by Jerry Van Amerongen
Solvay ala PhysLink.com
Jokes, jokes and more jokes
Chemist's equiVALENT Party
Is there Santa?
'Twas The Night Before Christmas, NASA-style
The Fate of the Universe
The Ten Commandments for Amateur Astronomers
Ask the Experts - Relativity
In General Relitivity, Acceleration and Gravity is the same; So does that mean that when matter accelerates it emits gravitons as do a gravitational force does?
How does gravity alter the trajectory of light?
I have read that gravity waves travel at the speed of light; does this mean that gravity waves are a part of the electromagnetic spectrum?
Is there any practical proof of time dialation on atomic particles?
If I were able to set a flashlight out in the middle of space and turned it on, would it move?
If an aircraft travelled in the opposite direction to the earth so that the earth had turned once would the occupants of the plane be considered as having travelled backwards in time?
Does time pass faster or slower close to the black hole?
I heard that the speed of light is the same to any observer, no matter how fast he moves, and that the faster you move, speed of light is still the same relative to you. Is this true, and why?
What is a light-year and how long is 1 light-year?
If a visible laser on the earth is shone on the moon and the beam is moved along the surface, could the beam spot on the moon be made to travel faster than the speed of light?
I am curious as to exactly when scientists found out that space is a vacuum and not made up of ether? What year was this and who is credited with the discovery?
If neutrinos both move at the speed of light and also have rest mass, what bearing does this have on relativity?
If nothing can travel faster then the speed of light, how does one explain Cerenkov Radiation?
What would be the force required to accelerate 1 gram to 20% of the speed of light?
Is there any practical proof for time dilation?
Is there a precise formula giving the increase in mass due an increase in velocity as described by relativity?
How fast a person must be going in a car to make a red light appear green?
Does gravity have a speed?
If it was possible to travel faster then the speed of light, would time reverse itself (like backwards time travel) or just not exist?
How are solar sails possible? If photons have no mass, how can they push on something?
Say you have a twin, and you go off into space, traveling near the speed of light, when you return, will your twin have aged more?
Is time quantized?
Now that the universe is proven flat, what implications does it have on the special theory of relativity, particularly the gravitational aspect?
Why is it easier to accelerate an electron to a speed that is close to the speed of light, compared to accelerating a proton to the same speed?
If the speed of light were infinitely large, would the effects of time dilation and length contractions be observable?
By what method is the size (or volume) of the universe at the moment of the big bang (or shortly thereafter) determined? Related to this, how is the size of a black hole determined?
If two lasers 1 mile apart and facing each other emitted a pulse of light at the same time surely the relative velocity between these 2 pulses of light would be 2c (c=speed of light). I was under the impression that nothing could exceed the speed of light so what is the true relative velocity between the 2 pulses?
What experiment or phenomena proved that light was bent by gravity?
My science data book says that the mass of a photon is zero. But how can photon exert radiation pressure, as it occurs in the sun?
If you're in a car traveling at the speed of light and you turn your headlights on, does anything happen?
What is rest mass? How to explain it especially to the high school students?
Are there any laws stating that time must flow in a constant stream (i.e. moments in unbroken succession)?
If an atomic clock is propelled at near the speed of light, wouldn't the definition of a second be distorted?
Does Einstein's mass-energy equation (E = mc
) imply that the mass of an object increases when we give it enough energy, be it kinetic or otherwise?
If the term 'absolute motion' has no meaning, then why do we say that the earth moves around the sun and not vice versa?
How does matter couple to space-time so that space-time becomes curved?
Why is the speed of light considered to be the universal speed limit, and would it be possible to ever exceed that speed with some advanced technology?
What is your opinion on Smarandache's hypothesis that there is no speed barrier in the universe?
I read somewhere that Einstein's formula is mostly quoted in the abbreviated version E=mc
but it should actually be written E
. Is that true?
Is it possible for a patch of light to travel faster than the speed of light?
Does a black hole violate the Law of Conservation of Matter/Energy?
Does the earth's mass increase?
Someone kindly explain,please.My atoms left the spot of the 'BIG BANG' at it's ocurance some 15 billion years ago.They traveled at a relatively slow rate compared to the speed of light.therefore,would not the light generated at BIG BANG time have passed me by and been long forgotten.Yet,we get reports of light from near the time of the BIG BANG just being received as if we had been here all along awaiting it?
Given that space is expanding, why is it that it is still '3,000 miles' from New York to San Francisco? Why is it that the volume of the space in a crystal lattice of, say, NaCl, still X cubic Angstroms? Doesn't 'local' space expand too?
Would not the speed of a light beam headed toward a black hole increase tremendously? We do know it could be bent by the gravity of a star.
'I thank You God for this most amazing day; for the leaping greenly spirits of trees and a blue true dream of sky; and for everything which is natural which is infinite.'
© Copyright 1995-2019 PhysLink.com