so effectively it's a paradox?Originally Posted by Broken
Socialism is simply the Collective denial of responsibility.
What is with the physics 101 stuff?
After you've all finished giving each other a group hug, care to discuss Bell's Intercnnectedness Theorem?
Glad to see the futality of religious applications hasn't changed much and I was able to set you straight.
Banned -- oh really -- Maybe I am Feynman's interference.
No paradox at all. Let's take a more concrete example.
Suppose you are the proud new owner of a a kilometer-long Beta-class starship. You have crewmen posted at the bow and stern with synchronized watches. Your bow crewman spots your buddy Moe in his Beta-class starship approaching from dead ahead at half the speed of light.
As Moe's starship flashes past, your bowman notices his watch has exactly the same time as Moe's bowman. However, when Moe's bowman flies by your sternman, you sternman notices that Moe's bowman's watch is running slow.
The crewmen on Moe's starship see the same effect in reverse. Your bowman's clock matches Moes's bowman's clock, but when your bowman passes Moe's sternman, Moe's sternman sees your bowman's clock is slow. This has to be the case, since the laws of physics are symmetric. In fact, Einstein relativity is the direct result of this symmetry.
Now take the "twin paradox". You take your starship on a round trip to Alpha Centuri. Moe, who is the same age as you, remains behind on Earth. When you return to Earth, you are now younger than Moe. How can this be? You and Moe moved apart and then back together. By symmetry, shouldn't you be the same ages? This is the so-called "twin paradox".
The reason there is no paradox is because you left Earth at one velocity and then reversed your velocity to return home. Moe never changed velocity, and so the situation is not symmetric.
Let's fix up the situation to make it symmetric. You and Moe both leave Earth at opposite velocities, travel the same distance, and then return to Earth. Your third friend Larry, the same age as you and Moe, remains on Earth the whole time you are travelling. You and Moe will now both be the same ages, but younger than Larry.
OK, you say, but what does symmetry have to do with you (or Moe) being younger than Larry? Let's find out. Say you have a TV link to Larry the whole time you are travelling, so you can watch each other age. What do you see?
On the journey out, you and Larry will be moving apart at high speed, so the TV signals between you will be doppler shifted to lower frequencies (red shift). To Larry, your TV image will appear to move slow and the clock he can see on your wall will run slow too. By symmetry, you will see Larry's TV image move slow as well. So far so good.
You get to Alpha Centuri and turn around. Since you are now moving towards Larry, your TV signal from Larry will now be doppler shifted to higher frequencies (blue shift). Your TV image of Larry will appear to move faster and his clock will speed up. Now for the tricky part! Larry is still getting a red-shifted TV signal from you and the TV image from you will still be moving slow to him!
Why? Because it takes time for your turn-around to effect the TV signal reaching Larry on Earth. If you were moving half the speed of light, you would be halfway back to Earth before Larry saw your TV signal flip from red-shift to blue-shift (slow-time to fast-time). However, you see Larry's TV signal flip from red to blue immediately at your turn-around.
This is where the situation is not symmetric. You see Larry's TV image sped up the whole way back to Earth. Larry doesn't see your TV image speed up until you are halfway home. So, you see more time passing on Larry's TV image than he sees on yours. He ages more than you.
I hope this helps.
Last edited by Broken; 24 Dec 04, at 02:46.
what's with this rogaine fellow?
Dude, no one cares.
Were we naughty? Is he the coal in our stockings?
-dale
He's certainly a good representation of the arrogance of mankind.
I try not to argue with those who believe in God, fact is there isn't a way you can completely disaprove it and frankly proof doesn't enter into the equation when talking about religion nor for that matter much rationality, its more about emotion. What you were raised with, what your culture tells you and what happened in your life.
In my experience you can not change anyone's religious beleifs through argument, beliefs usually change through life events, rarely is it because someone convinced them.
That said my belief is that given a infinite and eternal universe, any possibility is realized no matter how small or unlikely. In the religious community one would say well which belief is correct, answer maybe all of them somewhere somewhen.
As to the anthropic principle, for me the solution was just random chance, Given a infinite span of time and space there's bound to be a infinite amount of universes with our requirements. Probability in the scope of infinity is kinda funny, I mean probability is based on limits, on records of past effects, is there even probability given infinity.
One might say well something has a first cause, a scientist might say well the universe is infinite it had no first cause, on the other hand a religious person would say something very very similar, except claim God was always existing and in eternal and thus also had no first cause, that or God exists outside of time and and thus it doesn't matter, interestingly another common link between science as Hawking says time didn't begin either.
More later.
Sniper, better to look to string theory if you want FTL, neat stuff like Einstein Rosen Bridges etc.
" fact is there isn't a way you can completely disaprove it"
Fact is there's really no evidence whatsoever to disprove the existance of God.
"Sniper, better to look to string theory if you want FTL, neat stuff like Einstein Rosen Bridges etc."
Yeah, i've read a little about that, but not much.
If you were a trooper you'd hook us up with some good food for the brain on that topic here.
It does make you wonder if Galaxies just form on their own. It might be tough on the Big Bang theory if galaxies are still forming.
I tend to agree, though i still think Big bang is the best idea going to date.
If big bang follows the physics of an explosion each passing second should see the energy and matter needed to form explosions flung farther and farther outward in an increasingly large sphere..with an increasingly large void in between.
That would obviously make it harder to form galaxies.
Methinx it's got something to do with the supermassive blackholes which are believed to be at the center of all galaxies. Perhaps as time passes they attract more and more matter, allowing galaxies to form around them?
I also find it interesting that the total amount of matter in a galaxy is believed to equal the total mass of each galaxy's centrally located black hole(or did they change that theory too while i wasnt paying attention, lol).
Last edited by Bill; 24 Dec 04, at 13:54.
Yeah, but there isn't convincing evidence to beleive in god either; so why not take the less complex route an assume the negative?
For example, you can't disprove that an invisible man that only I can talk to lives within the walls of my house. But why beleive it? Simply because it is more comforting?
I understand that it is necessary for many people to beleive in God simply to make their lives bearable, but I think this is a sad situation.
The book the Elegant Universe by Brian Greene is pretty interesting if you really like physics. Otherwise just watch the NOVA series of the same title on PBS."Sniper, better to look to string theory if you want FTL, neat stuff like Einstein Rosen Bridges etc."
Yeah, i've read a little about that, but not much.
If you were a trooper you'd hook us up with some good food for the brain on that topic here.
The physics snobbery by robbains2 is not appreciated though. If he wants to relate something to physics, he can explain it to everyone.
Great explanation of the twin paradox Broken...
There is no such thing as an atheist in a foxhole.
Chimo
If I had a choice of believing in the negative v. positive, I would first believe in the positive. Secondly, if it is your presumption that God lives "in the walls of your house," no wonder you are leaning toward the negative and relying upon physics. It would take physics to figure how he got into your "walls" in the first place.
If you can read, comprehend, and interpret the writings of God, you will find that it is not the "walls of your home" he resides.
Because the other choice is random chance. Things are too oganized for me to take luck as my God, though you may if you wish.
No man is free until all men are free - John Hossack
I agree completely with this Administration’s goal of a regime change in Iraq-John Kerry
even if that enforcement is mostly at the hands of the United States, a right we retain even if the Security Council fails to act-John Kerry
He may even miscalculate and slide these weapons off to terrorist groups to invite them to be a surrogate to use them against the United States. It’s the miscalculation that poses the greatest threat-John Kerry
Thanks! I have always been frustrated with most twin paradox "explanations", so I thought I would write my own. I am afraid I was a bit cryptic in my use of the word symmetry without explanation.
Symmetry in physics means to do something to a system and have it remain the same. For example, if you rotate a cube by 90 degrees it looks the same; it has cubic symmetry. If you rotate a sphere by any angle it looks the same, so it has spherical symmetry.
Energy is symmetric with time. You can change the time coordinate of a closed system and the energy remains the same. In other words, energy is conserved.
Getting back to relativity, any observer moving at constant velocity relative to another observer has the same laws of physics. The laws of physics are symmetric for observers moving at any constant velocity. If you add the fact that the constant speed of light is a law of physics, you get Einstein's special relativity.
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