NowThatWeKnow

what about something like a mirror surrounding it. or at least something shiny. that would reflect everything right?

I am far from an expert but I did find this. Remember visible light is only a small portion of the EM range.

http://en.wikipedia.org/wiki/Uranium-238

"Uranium-238 is also used as a radiation shield — its alpha radiation is easily stopped by the non-radioactive casing of the shielding and the uranium's high atomic weight and high number of electrons is highly effective in absorbing gamma rays and x-rays. However, it is not as effective as ordinary water for stopping fast neutrons. Both metallic depleted uranium and depleted uranium dioxide are being used as materials for radiation shielding. Uranium is about five times better as a gamma ray shield than lead, so a shield with the same effectivity can be packed into a thinner layer."

... but if radiation in space is just photons, wouldnt anything thats not see through stop it? ...

Different frequencies are very different. X-ray is an electromagnetic radiation you are familiar with that penetrates and then you have gamma rays.

C is invariant, there's a brake in symmetry when the travelling twin changes direction...cameron marica, if you want a full description of what that means, I'm more than happy to describe it layman terms...

More then just cameron would benefit from you (or anyone else) putting it into layman terms. Two frames are doing the same thing relative to each other so what determines which twin stays younger? It seems that acceleration, deceleration and gravitational potential are the only differences to be considered. I recently read where the clock speed differences are consistent during a trip and do not happen at one point.

...Time is the same to each person in their own element. The "traveling" person will say the "stationary" person aged faster than normal and the "stationary" person will say the "traveling" person aged slower than normal? Who is right? They both are...

But one twin is older then the other when they reunite.

this time dilation stuff is just so hard to wrap my head around...

You are not alone. As many times as I have read about the twins, it still confuses me. I was reading an article just yesterday about time differences between two inertial frames with no acceleration involved. I thought that acceleration is what broke the symmetry between the clocks but now I am not so sure. How else would you know who is traveling and who is at rest?

There is a difference in clocks running at different speeds and stopping the clock. The twin story I read said the difference in age was years, not seconds.

http://www.phys.unsw.edu.au/einsteinlight/jw/module4_twin_paradox.htm

The universe is space-time. The universe is expanding into empty space. Beyond there is no matter at all, not even a few atoms per cubic LY, so it is not space-time, it is only space, black, cold empty space. Nothing is more simple than that.

Maybe not simple and far from fact but it is easier to think about than a universe with a boundary or one without.

Quantum theory = very small

Infinite universes = very large plus pure speculation

This thread may experience a relativistic ride.

Welcome Maybe we are the "cursor".

Very interesting but with a lot of unknowns. I wonder if these massive black holes may be another source for heavy elements in the galaxy. It would seem there would be plenty of pressure and energy for developing them and the jets could disperse it.

lol, sounds good i shall do that this weekend, know any theory's that have any sort of relation to mine?, any other books?

You can find all sorts of things over in the "speculation" section. Other areas of this forum require something to back them up like math or observations.

does anyone have any links to any sites on black holes

I guess you already absorbed all the information in the link iNow posted?

I can see where "illusion" may not fit much of the time. When two frames meet, the results will not be an illusion. Thanks for the replies.

...Of course kinetic energy depends on how fast you consider the object to be moving.

Exactly, the kinetic energy and relativistic mass are equally varible depending on what you are comparing your speed to.

He probably meant just slowing down. That's it. And would doing so make time go faster. It's the reverse of speeding up, and time would move slower.

You may be right and I was confused by "but can we move something "negatively" somehow? so a reference points ages faster than another reference point moving at normal speeds?" If so he was sort of answering the question before he asked it.

i thought this was a good description of the matter

http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html

It makes it sound like gamma [math] y[/math] is some kind of resistance in space despite the fact that a continuous 1G acceleration will cover more distance at a faster and faster rate according to your clocks on the ship. Earth time is the one that seems to be stuck at the speed of light. That could be a relevant factor on a trip.

But only if we were the same distance away from the black hole as we are from the center of the Earth now, right?

Someone please correct me if I am wrong but I would guess that gravity 4000 miles from the black hole would be similar to gravity at the earths surface. A new set of rules apply as you get closer to the black hole. Going towards the center of the earth your weight would decrease and getting closer to the black hole your weight woud increase. All bets off when you get close to the black hole. Again, corrections welcome if needed.

Edit -

I love it when I am right. finally

http://amazing-space.stsci.edu/resources/explorations/blackholes/teacher/sciencebackground.html#5

A variable value that is only relative to someone else does not seem very relevant. Unless maybe when you are using a particle collider.

Traveling back in time takes advance planning. If you want to come back to 2010 in 2020 you could send Earth on a relativistic trip now and wait on Mars for it's return. As mentioned, you could do the same with gravity. But even if you could ignore the gravity of the Sun and Earth you would only go ahead in time by about 1 minute a year. As Baby Astronaut says, "unless my calculations are totally screwy"

What time is it inside a black hole? .. If time changes does to gravitational effects, could the time be either 0 or infinite?

A black hole could have the mass of the Earth or millions of stars. A black hole with the mass of Earth would have a similar gravity as Earth. And I would think a similar time dilation. I have a feeling that stopping time is like reaching the speed of light. You will never quite get there.

If relativistic mass is only seen by an observer outside of the particular frame in question, it must be an illusion. You could have several inertial frames moving about at different speeds and no one could agree on the relativistic mass of each one, yet they would all agree that their own mass is at rest.

Another question: Would a rotor with a larger curve on the top do better than one with a smaller one? In Bernoulli's principle, it says lift is achieved by the lowering of air density because of movement... so a bigger curve would mean more lift, wouldn't it? Or does it need to be more aerodynamic so it can move faster? And what would be the best type of metal? Would aluminum work, or is it too flimsy?

NASA Foilsim will let you calculate lift with different angles of attack, airfoil size, camber and speed. Change the "Input" field for different options.

http://www.grc.nasa.gov/WWW/K-12/airplane/foil2.html

The lithium ion battery would give the most power for weight and is used in radio control aircraft with excellent success. It does get pricey as the size goes up.

... However, the energy is hard to be released...

I agree. A one kilogram rock equivalent to [math]8.98755179 * 10^{16} joules[/math]. As mentioned, antimatter is our only hope.

If the twins start at the same "now" and end at the same "now' with their clocks, which measure time, showing diffrent values, time as we measure it cannot accuratly show the rate of progression of "now".

Your head ages faster then your feet and they share the same "now".

"...sound like an Abbott & Costello bit." Yep

The definition of "now"

http://www.einstein-online.info/en/spotlights/Now/index.html

"two events are simultaneous if and only if they can be seen on the same photograph, taken with a double camera placed exactly in the middle between their locations."

...which is why these discussions occasionally sound like an Abbott & Costello bit.

I resemble that remark.