How does space work? What are the key laws of physics?

Question

How does space work? What are the key laws of physics?

Answer 1

Einstein laid out how space time works.



Special Relativity: Space time is elastic and expands and contracts such that the speed of light is constant for all observers



We start with the Train and pitcher thought experiment.

You are standing on the ground next to a train track. A train going 100 km/hr is going past. On a flat car is a baseball pitcher that you know can throw 195 km/hr fastballs throwing toward toward you. You have a radar gun so you can measure the speed of the baseballs.

What speed would you measure if the train was coming toward you? (100 + 195 = 295 km/hr )

What speed would you measure if the train was going away from you? (195 - 100 = 95km/hr)



Now we start Special Relativity:



Toward the end of the 1800s scientists measured the speed of light compared with the speed of the earth in orbit. They expected that knowing the speed of the earth going toward the source of light the velocities would add and that when going away from the source of light the velocities would subtract. BUT that is not what happened. It did not matter if they were moving toward the source or away from the source, they got the same value: roughly 3 * 10^8 m/s. VERY STRANGE! They were sure something was wrong. It was not possible, based on their assumption that Time and Space were absolute (unchanging) for that to be true.



Einstein's insight: He thought,"What if the speed of light IS absolute and Time and Space could change to make that true? What does that do to everything else? He worked it out for all the physical quantities. It works! What you get is consistent with what we observe in experiments.



This site will let you play with what happens at near light speed

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/relmom.html



Buiding on the concept of elastic space time we get General Relativity



General Relativity: Another thought experiment: Einstein thought, "What exactly is gravity?" Newton described how gravity worked but could not figure out what it was. Example: The earth is attracted to the sun. But, how does the Sun do that? Where is the "rope" that allows the sun to pull on the earth? Newton ignored the question.



Einstein tackled it. And thought (My paraphrase): Suppose you were captured by aliens and drugged, you wake up in a sealed room. The room could be sitting motionless on the earth or you could be on the alien’s spaceship being taken back to their home planet. The space ship could have a soundless, vibration less rocket motor that we cannot tell if it is firing or not. If it is firing it is accelerating the room at 9.8 m/s^2 Is there any experiment that we can do that will allow you to figure out if the room is sitting motionless on the earth or accelerating through space at 9.8 m/s^2? Turns out there are no way to figure out if we are sitting on earth or accelerating through space. This means: If we cannot tell the difference, then there is no difference. ===> Gravity is not a force but acceleration that manifests itself as a warping (curving) of Space-Time. (A very profound conclusion. Newton caught a whiff of this insight, but missed its’ significants. F = MA To get a Force you multiply Mass times Acceleration).

Another way to say this: Masses are not attracted to each other, they just follow the curvature of space-time. The acceleration of gravity is the slope of the curvature of space-time.



Einstein knew from Special Relativity that acceleration would warp Time and Space ===> Gravity is mass warping Time and Space (Space-Time) ===> General Relativity



The warping of Space-Time is necessary for General Relativity. Einstein's reasoning requires it. If it was a force as Newton proposed, then if the mass of the sun disappeared the earth instantly leave its orbit. But, Special Relativity says that nothing, not even gravity can travel faster than light ====> It must take about 8 minutes for the earth to leave its orbit after the sun disappeared. With GR there would be a "ripple" in the fabric of Space-Time that when calculated actually moves at c. All this would be conjecture except we can test GR and its predictions are accurate

Very nice graphic of the Gravity Ripple at:

http://www.pbs.org/wgbh/nova/elegant/program.html

1st Hour – A New View of Gravity



The "proofs" are down in Section 4



http://en.wikipedia.org/wiki/Introductio…









We assume that the laws of physics are the same in all locations of our universe. Observation seems to conform this and that assumption allows us to apply our physical theories and laws to our observations of the universe. If it were not true then we would have no basis to make conclusions. Since we cannot test it in all locations, we cannot prove that it is correct, but it does seem to work and the results we get make sense (we get what we expect)..



http://en.wikipedia.org/wiki/Uniformitarianism_(science)

Answer 2

1. Space seems to work according to Einstein's theory of relativity, which ties together the concepts of space, time, gravity, matter, and energy, with (complicated) equations that mostly include the number "c", which seems to be a universal constant, and which is also the speed of light.



Not sure if that's what you wanted. Your question was a little vague.



2. The key laws of physics seem to be the same throughout the universe. In fact, generally speaking, that's more or less a prerequisite; something doesn't get to have the title, "law of physics," unless it is (as far as we can tell) a principle that applies everywhere.

Answer 3

How does space work? What are the key laws of physics?

Hi.I really need help with some questions. I'm not asking you to answer it (but if you could, that would be great), but I just need help to narrow my search down. My questions are:

-How does space work?

-Are the key laws of physics different throughout the universe, and how?





Space is the Universe

The “Laws” of physics describe the relationships between the matter and the energy of which the Universe is composed.

What forces hold the objects in specific places relative to each other?



See the web site below

http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html



What holds the nucleus of an atom together?

The strong nuclear force attracts the protons and neutrons toward each other.



What holds an atom’s electrons around the nucleus?

The electromagnetic force controls the motion of charged particles and the effect of the magnetic fields produced by moving charges.



What causes a nucleus to be stable or unstable?

The weak force is responsible for radioactive decay and neutrino interactions. It has a very short range and, as its name indicates, it is very weak.



The Force of Universal Gravitational Attraction is the force which causes the mass of one object to be attracted to the mass of a 2nd object. mass.



These 4 fundamental forces control the position and interaction of all the objects in the Universe.



Go to the website below for information about the Key laws of Phyiscs



http://physics.about.com/od/physics101thebasics/p/PhysicsLaws.htm



Newton’s 3 laws describe how physical object interact with each other as they exert a force on each other.



The law of Gravity describes how object interact due to the fact that all objects are attracted toward each other.



Conservation of energy and mass tells us that the total amount of energy and mass that exists in the Universe toady, is the same as the total amount of energy that existed at any time in the past and any time in the future.



Conservation of momentum describes the relationship between the mass and velocity of objects before and after a collision. Conservation of angular momentum describes how the rotation of the Earth increases the stability of the Earth. When an meteorite strikes the earth, the Earth does not wobble like a weeble.



The laws of thermodynamics describe how heat energy is transferred from one object to another. Heat energy is really the sum of the kinetic energy of the atoms, ions, and molecules of which a substance is composed. Temperature measures the average kinetic energy of the atoms, ions, and molecules of which a substance is composed!



Electrostatic laws describe how the electric charge of a particle affects other particles.







The laws of relativity are the only laws which describe how matter and energy are related. The fact that the speed of light in any specific medium is constant and the fact that light does not accelerate from 0 m/s to the speed of light determine the how all the forms of electromagnetic radiation interact with physical objects. The theory relativity describes how velocity affects the inertia of physical objects.



All these “Laws”, are really just descriptions of how all the parts of the Universe relate to each other. The world does not obey the laws! The laws describe the behavior of the world!



From the physics point of view, SPACE is what exists between all the matter in the Universe. Space is a necessary ingredient of the Universe, because otherwise, all the matter would be lumped into one giant sphere. This does not exist due to the attraction and repulsion caused by the forces.



Space does no work, but without space, no work can be done.

The space between the planets and the sun, the gravitational force of attraction, and the velocity of the planets keeps the planets in their orbits.



The space between the electrons in the shells and the protons in the nucleus, the electrostatic force of attraction between the + and- charges, and motion of the electrons relative to the nucleus prevents the atom from collapsing.



I am going to eat supper now.

I have enjoyed how the laws of physics have allowed me to communicate with you, even though neither of us knows where the other person is right now.

I will enjoy how the laws of physics help me walk down the stairs without falling.

I really appreciate the space between the atom in the food I eat. Otherwise, I would be chewing on SOLID MATTER, like trying to eat a rock!



Rocks have space between the atoms, otherwise erosion would never occur!



I must stop or the law of thermodynamics will make my food be the same temperature as the kitchen!!



This has been fun!!