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I’ve been looking through the organic chemistry thread, and I’ve been getting jealous because the people seem like they’re having so much fun discussing organic chemistry and I wish I could join the discussion but I don’t know the first thing about organic chemistry.
So I’m starting this thread for people to discuss physics.
Discuss.
I once threw a big rock at a fish tank and the glass broke.
Can someone please explain to me, in detail, the theory of relativity?
Specifically, how is special relativity different than general relativity.
Meno – not fair! Now there will be two threads about topics that I am clueless about 🙁
is this a copy of my thread of organic and a and p??? before i even read it thats what i thought!!
lilmod ulelamaid – look it up!!
i love physics but bad at it just like all the other sciences!!
joseph – according to wiki “In 1905, Albert Einstein determined that the laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of all observers. This was the theory of special relativity”.
Joe -“Can someone please explain to me, in detail, the theory of relativity?”
Why don’t you ask your relative Einstein?!?
I don’t even understand Joseph’s question – I haven’t learned science since 10th grade!
Famous physicist richard feynman on quantum physics: ” It is my task to convince you not to turn away because you don’t understand it. You see my physics students don’t understand it… That is because I don’t understand it. Nobody does.”
He, or someone else like him said: (I don’t know the exact quote but basically):anyone who claims to understand quantum mechanics doesn’t understand it.
lilmod ulelamaid – thats sad:( science is the way to go! i LOVE science even tho im bad at it.
Meno – joseph asked someone to explain it so i got wiki to do that. also its insulting to call someone smartypants so you owe me an apology.
feivel – phsyics is VERY HARD to understand. do you know that physics proves that their has to be a G-d in this world because they did a VERY famous experiment where they sent particles through a wall and saw that they reacted differently when nothing was watching them from when someone was watching them saying that stuff that your NOT looking at go to a different dimension when your NOT looking at it. its so scary and cool at the same time and it proves that G-d exists because how can this happen if their was no G-d????
Meno – because how could this happen if their was NO G-d???
Meno – i guess im more religious than you because i look at it from a view of a religious persons view. i view it as that G-d made everything for a reason and for a beautiful reason and EVERYTHING proves that G-d exists.
there was this nice problem I read the other day. You are in a boat on a lake. There’s a rock on the boat. If you throw the rock into the water, does the water level goes up or down?
It’s very easy for anyone who’s learnt physics.
It’s called the double slit experiment and you described it in its essence quite well.
I think the only thing it conclusively proves is that things are not always (probably not ever) as we rationally understand them.
It is highly suggestive however, along with all the other “spooky” (as physicists themselves refer to them) occurrences, that there is something out there that gives causality to the universe that we may be too limited to be capable of understanding
feivel – you got me. thats exactly what i was talking about! and i call it “spooky”. i love physics because of this. i love astronomy as well. theres SO MUCH above our sky its “spooky”.
You love it because Hashem can be felt there more readily.
That’s what the “beauty” in the world is that artists try so hard to capture but really can’t.
It’s Hashem that they sense in the mountains and clouds that stirs their hearts. In physics and biology and such, if you are sensitive to Him, He stirs the emotions of your intellect.
Rabbi Avigdor Miller, zt’l called “nature” the other Torah. It’s the Torah that Avraham Aveinu learned.
Special Relativity posits that:
1.) Evreything in the universe is always “moving” at a constant speed (“C”)
2.) The Universe is made out of a 4 dimensional fabric comprised of 3 spatial dimensions and 1 time dimension
3.) By necessity an object moving through any one dimension goes slower through the others. (Imagine a car going straight east and another going north east. The car going north east will cover less ground in the eastward direction. Same thing with the dimensions of spacetime an object moving through one of the spatial dimensions will by neccessity move slower through the time dimension.)
4.) Being that light has no mass to “hold” it in one of the spatial dimensions it moves at a constant speed of C through the spatial dimensions. An object with mass that is at rest will have all of its movement happen in the time dimension.
General Relativity posits
1.) All of the above
2.) spacetime curves in the vicinity of a massive object.
3.) Left to their own devices an object will travel in a straight line through spacetime.
4.) When spacetime is curved an object will follow the curve.
5.) Gravity is not a “force” but rather it is the result of an object moving along the curvature of spacetime. (The famous ball on a rubber sheet thing)
6.) Gravity is in essence the acceleration (change of direction in the movement) of an object in spacetime due to the curverture of the fabric it is traveling through.
7.) A gravitational field and an acceleration are the same thing
WB 000646!
Sparky: You are falling to a common fallacy of quantum mechanics. People who think they understand quantum mechanics (unlikely, as the “father” of the science, Werner Heisenberg, stated that nobody fully understands it) like to apply all sorts of metaphysical aspects from it. Truth is, its just another branch of physics, like momentum, gravity, or nuclear power. There’s nothing “special” about it, and certainly nothing that proves that there’s a Ribono Shel Olom. “Observing” a particle is just a fancy way of saying “shooting smaller particles at it”. If the particle is small enough, the smaller particles (usually photons) knock it off course making it impossible to measure. Hence the Double Slit Experiment and Heisenberg’s Uncertainty Theorom.
Do you know why Chazal say that looking up from Torah to say ?? ??? ???? ?? is chayiv misa? Because the person is learning the wrong way! How do we know? Because he sees the beauty in a tree, but not in Torah! If you need to look to science to see the “proof” of Hashem Yisborach, you are looking in the wrong place.
Joseph: Read Stephen Hawking’s A Brief History of Time or Brian Greene’s The Elegant Universe
Special Relativity: There’s no such thing as “how fast is it going?” There’s only “how much faster than the other thing is it going?” All speeds are relative to something else. In our context, that’s usually the Earth. The one exception is light. No matter how fast you are going, the photons that make up light will always be traveling 299,792,458 meters per second faster than you.
General Relativity: Everything in physical existence is in a four dimensional medium called “the space-time continuum” (our three dimensions, plus time which in higher physics is treated as just another dimension). Picture it as an endless sheet of rubber. Everything with mass “bends” space-time, bigger objects bend it even more. So when you come near a really massive object, you start slipping down the a slope in space-time. That’s what we call gravity.
Yserbius123 – i said or at least i thought i said i DONT understand it. when did i say i understood it?
Meno,
To observe something you have to interact with it in some way. For example in order to see something you have to bounce photons (light “waves”) off of it back into your eyes. On “normal” sized objects the effects of bouncing photons off of an object is too small to make any practical difference. When you get down to the quantum level the difference becomes quite significant.
Now, finally, someone has given a rational explanation of the double slit experiment!
Interaction with photons. I like that. Makes perfect sense. Undeniable logic.
Now if only the physicists would hear about this they would cease their skepticism and insistence that the double slit experiment admits to no rational explanation.
Sparkly is the only one here who understands the double slit experiment. Her wonderment and appreciation is very much like that of the greatest physicists themselves, albeit with less understanding of how truly “irrational” it is.
Meno,
Your eyes don’t give off any particles, and neither do cameras. Both things see by collecting photons that bounce off an object onto them. If no photons are bounced off the object then all you would see is dark. You wouldn’t see anything.
Bouncing a photon off of an object will change either its position or its velocity. On a normal sized object this occurs as well but the effect is just too small for humans to notice. On the quantum level it becomes much more significant. It is therefore impossible- even in theory- to ever know the exact velocity and position of a particle.
The “observation” that occurs during that particular aspect of the double slit experiment refers to photons that are gathered by a sensor. But the OTHER photons that “miss” the sensor are the ones that behave differently in a situation of observation wherein their fellow photons are captured.
The process of observation itself has no known physical interaction with the particles being studied. THAT is the wonder of the experiment.
And photons don’t hit or deflect other photons like little balls.
Meno: Zero meant that ambient photos from light sources in the room bounce off the photons and enter the eye or camera. He didn’t mean the eye emits photons. (although the eye does actually emit an insignificant amount of photons). Of course the observation referred to here is neither by eye nor camera.
Memo and Feivel,
I wasn’t talking about the double slit experiment. I was addressing Menos question about what particles are shot out of someone’s eyes when they observe something.
zero, you are correct that the exact position and velocity (more correctly momentum) cannot be SIMILTANEOUSLY determined precisely for an individual electron, even theoretically. This is not because of interaction with other particles but because in their essential existence an electron simply doesn’t have a definite existing simultaneous position and momentum! It is a matter of probabilities.
I don’t claim to really understand this Heisenberg principle. Physicists are apparently unable to grasp it either though they can certainly describe and use it.
I think you are correct Meno. Both in understanding what zero has said. And another reason as to why he is wrong.
It’s a lot more complicated than that, but essentially works out to the same thing. Certain subatomic particles have bizarre properties that defy our standard rational understanding of the physical world. They don’t actually exist in one particular place at one particular time, unless they are observed. So, an unobserved electron traveling from point A to point B can’t be visualized as a ball flying from one place to the next. Instead it’s more like a wave, with the peaks and troughs representing possibilities as to where the electron may travel. Technically, it’s actually traveling through all possibilities.
?????? ??? ???. Because it gets weirder.
Now, using classical Newtonian physics, we “know” that the particle must be somewhere along that wave. Like in the double slit experiment, it either travels through slit 1 or slit 2. Right? So we put sensors on each slit to see which one it goes through. Alright, now the sensors are sending back data telling us which side the electron went through. Except now that the electron-wave isn’t a wave anymore, it’s a particle, acting like a ball being thrown through a hoop. How does it “know” when it’s being observed? It has nothing to do with whether someone’s eyeballs are on it, or if someone watched the DVD, or any of that metaphysical nonesense. It’s merely a question of whether something “hit” the wave on. The sensors give off photons (or other equivalent sub-atomic particles) which interact with the wave, forcing it to stop being a wave and start being a particle.
Imagine, if you will, watching waves crash ashore on a beach. Now imagine that if you stick your hand in a wave, the water disappears and a beach ball appears, sometimes in your hand, sometimes a few feet away. That’s sort of what’s happening.
Confused yet? Good. It means you’re starting to get it.
“I wasn’t talking about the double slit experiment.”
I see, so then you DONT have an explanation of the observer effect in the experiment?
Or if you do, can you please explain it again, or copy from a previous explanation? thanks.
And you also aren’t claiming that: the Heisenberg Principle can be explained by the fact of the necessary interaction of particles that occurs during observation?
L’havdil, when R’ Akiva Eiger would write ??? he wasn’t saying “There’s no explanation”, he was saying “I am not wise enough to understand this.” Same thing over here. There is a rational explanation for the Uncertainty Principle and it is well understood among physicists. It’s just far to complicated and, unless someone here is works in particle science, no one on this thread understands it.
Yeserbius: up until you said: “The sensors give off photons (or other equivalent sub-atomic particles) which interact with the wave, forcing it to stop being a wave and start being a particle.” you were correct. You are positing that there is a physical element to the observation that is causing the particle aspect of the photon to come into existence.
Unless my understanding of the implications of the experimental data are flawed, this is not the case. When the photon stream is being observed, those particles that have NOT interacted with anything will exhibit particle behavior and characteristics, not only the sampling of photons that have necessarily undergone interaction.
When the photon stream in general is not being observed then particle nature is not exhibited in the end result on the screen.
In other words, it would come out from the DS experiment that IF YOU COULD observe each photon with ZERO interaction or influence, ( say by some form of mental telepathy or time shifting) STILL the observer effect would be present in full.
It’s not a matter of being confusing to understand. It’s a matter of it not admitting to any rational understanding, as our rational understanding is today. That why physicists themselves have turned to “metaphysical nonsense” to explain it
Your misunderstanding is common. As you can see from zeros mistaken explanation of the Heisenberg Principle, which also has to do with “observation”. See my earlier post on this if interested
I don’t wish to take up anymore time on this. It’s quite unimportant to me.
What is important is that Sparkly maintain her correct amazement at what Physics is constantly uncovering.
It is NOT logical Sparkly. It is NOT rational. We are at a COMPLETE loss to explain it. That’s my message to you regardless of what else you will hear on this thread or elsewhere. That’s what I would personally like to accomplish here.
” There is a rational explanation for the Uncertainty Principle and it is well understood among physicists. It’s just far to complicated…..”
Yes there is. But it has nothing whatsoever to do with what you brought as the explanation. It has nothing to do with particle interactions.
The explanation is as I stated earlier: an electron has no location or momentum to be pinpointed. It is as you pointed out a map of probabilities of certain behaviors that may be manifested at certain times and locations.
They understand this and the mathematical manipulation of it well.
But no one, not just us, claims to have a rational grasp of it. or explanation of it in terms of human experience.
And when it comes to the observers effect of the DS experiment, they only have a slew of vastly differing metaphysical highly theoretical constructs to even touch it.
I quoted Feynman above. See my first post (I think).
I just found this one when he was asked about Relativity:
“….but after people read the paper a lot of people understood the theory of relativity in some way or other, certainly more than twelve. On the other hand, I think I can safely say that nobody understands quantum mechanics.”
Maybe you’ll tell me he wasn’t including Heisenberg’s Principle in these statements. I think he was but I have no definitive knowledge with which to argue that point.
Meno: Ok. But those are no fun 🙁 Newtonian physics can basically just be boiled down to conservation of momentum.
How about Maxwell’s equations? You can never have perpetual motion, and you can never extract 100% of the energy from anything.
Meno, but if the boat is lighter it doesn’t sink as deep as before, and so it displaces less water. Isn’t it so?
Meno. Depends on the density of the rock.
Exaggerated case: Rock the size of an aspirin. Weighs 100 lbs. will push the boat deep into the water. When removed from the boat a large volume of boat ( say 20 gallons) will no longer displace water causing a lowering of the water level. This will be only minimally compensated for by an increase in the water level equal to the volume of the rock.
If you enjoy extreme cases here’s a potentially actual (though not practical) case. Take a teaspoon worth of a neutron star. You will need an extremely strong and massive boat to make this work. A teaspoon of a neutron star weighs about a billion tons. That would cause a ginormous lowering of the water level when superman lifts it up from the boat. But it will cause a displacement when thrown into the ocean only equal to its minuscule volume.
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