Physics

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Originally posted by russ_watters
2)Science was also hindered by religion (and still is in many ways).

Rado, thats not an opinion unless you don't think Galileo (just one example but the best) was at all hindered by being arrested and imprisoned by the catholic church. He was recently pardoned actually - not that it did him much good as he had been dead for 500 years or so.

Another good example is a bunch of scientists sat down with the pope a few years back and he explicitly told them not to research the big bang. Hawking mentions this in A Brief History of Time.

In fact, FACT, the Catholic church does all it can to stop science that it doesn't agree with - both historically and today.

One funny thing about Aristotle - he believed that EVERYTHING could be figured out by pure thought. So he did almost no experimentation or observation. He was so bad in fact that he once postulated that a fly had 4 legs like a table. It made sense to him, but it never even occurred to him to catch a fly and check for himself.

His theory on gravity would have been easy enough to verify as well - it only takes a few objects dropped off a building to see that the idea that falling speed is proportional to weight is wrong. But hey - if you got logic, why do any testing, right?!


stoo, you're right that by mass matter/antimatter reactions are more energetic than nuclear ones, but for that to be useful there has to be a lot of antimatter generated - and the evidence suggests there isn't enough for it to be useful.

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The fact of the matter is, every single instance of religion clashing with science you have mentioned, has to do with either the Catholic Church or Christianity in general. That is ONLY ONE RELIGION. There are many many more in the world. Myself, I am a Hindu. Throughout our sacred texts, scholars, priests, temples (equivalent to a church) we condone and encourage scientific thinking. In fact, of our 4 "main" holy books, one deals ENTIRELY with scientific methods and theories.

One great Hindu scholar wrote a fabolous book, entitled Vedic Mathematics. The Vedas were one of our holy books. What's interesting is there are so many topics covered in Vedic Mathematics that are fresh and interesting and that haven't been covered in conventional math. They range from simple to complex. Some of the simple ones involve multiplication tricks such that you can do decimal multiplication very easily (using these tricks) in your head without a calculator, with practice, of course.

Just because the Catholic Church (or Christianity) opposes/interferes with Science doesn't mean all religion is opposed to Science.

Personally, I would be very suprised if there were no Catholics working on proving the Big Bang. Religion has never hindered science. Men have hindered science, but that's all.

i'm not sure if you got your question answered cause i'm not going to read it all, but yes you can see the light. I don't see how that disproves general relativity... you would see it reflect off stuff definitely (although it would be at a distorted angle blueshifted so much that you couldn't see it)... but since you aren't traveling along a straight line with the light, you would still see SOME of the out just because the light is not traveling in the same direction that you are, so you have an advantage in that geometric respect. If the angle between the light's trajectory and your travel direction is large enough and the difference between your speed and the speed of light is small enough, then yes... you would even see a little bit of the light that was shining out... again at a very distorted angle, but this light would be redshifted so much that you couldn't see it... however if you're assuming the light and yourself are traveling along the same path, you will only see the light reflected... and none of the light originally came from your lights because it will always "outrun" you.

I guess the best way to think of it is assume you're a fat police officer and running in 1 direction and the light is a UHAUL truck that you just pulled over and lots of faster people are constantly jumping out and running in straight lines, but in all directions... so if you "got a good angle" on the faster people, then you can catch him... because you catch him from the side and not from directly behind him.

Hope that helps.

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Originally posted by andy3109
[B]Well first of all if you were traveling that fast yes you would see the light in front of you. This is for the same reason that if you shot a bullet on a train moving 1000 miles per hour. The bullet would just be travling 2000 miles per hour. Another words the car is already moving at a certain rate, anything that is static or has a force behind it will remain static or move ahead of the car. (if that makes any sense to you)
-andy

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these are characteristics of sound, not light... light is not a compressional wave.

edit: after reading it again, i've decided i've misunderstood what you said, but cannot understand it eventhough i've read it again.

I'll add some more, Sinnersis. One thing that I find crazy about quantum particles is "spin". Imagine a white soccer ball with a black spot on one side. You will have to turn it 360 degrees in order to see the black spot on it again. This is called a spin of one. Now put a dot on the other side so that you have two dots. You will only have to rotate it 180 degrees in order to see the black spot. This is a spin of 2. Now what is crazy is a spin of 1/2. Imagine just one spot on the ball. You actually have to turn it 720 degrees in order to see the black spot again. This is two full rotations. I don't know why this is but it is just one of the many things that are bizarre when you look at quantum physics.

"3) There definately are other universes. The Heisenberg Uncertainty Principle makes this so. Anything that can happen will happen. For instance, there is a universe where Greenland is the super power of the world. There is also a universe where I am the richest person in the world."

Though the multiple universes theory has a good following, it isn't required by the heisenberg uncertainty principle - and it is far from universally accepted. It simply says that you don't know the exact position and velocity of a particle (or that the particle doesn't have an exact position or velocity). Not knowing what the particle is doing is not the same as the particle doing everything at once.

Another way of putting it is that heisenberg works inside THIS universe - it doesn't work by being OUTSIDE it.

I didn't say or imply that ALL religions ALWAYS try to hold back science. My point was simply that some do - often.

Its true that the Catholic Church is by far the worst in that, but then virtually all of modern science and technology has happened in their neck of the woods, so if any religion were to try to disrupt it, it could only be the Catholic Church/christianity. For Galileo, for example, there was no other religion to deal with.

I also didn't say that NO religious people work in science - plenty do. Its largely the church government (catholicism is also the only religion to BE a country) that tries to subdue science.

While I single out catholicism, it is by no means the only religion to butt heads with science (though it is the worst).

And elimc, whether religion is the people or can be considered an entity unto itself is not something I wish to debate. You can easily view it either way.

The best way to think of spin is not to do it three dimensionally but to use higher dimensional plains. (As you would when thinking about "folding space.")
To add to this it is possible for a particle to have several different states of spin on top on one another :confused: - which helps lead to the use of electron spin in quantum computers.
This is largely particle physics, dealing with the fundamental particles.

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Originally posted by elimc

1) Matter and energy are the same. Remember, E=MC^2.

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Matter and energy are not the same. There is a conversion ratio between them; the equation E=MC^2 indicates that if matter is converted to energy on a nuclear level, in a perfect system, with no energy loss, the amount of energy released from matter of mass g will be g*(2.99X10^8)^2.

Mass->Energy is far far easier than Energy->Mass conversion.

I have another question (been arguing about this for weeks with a colleague) in a similar vein to the first...

One Taurus (500kg) travelling at 100km/h collides with another stationary Taurus (500kg). Is the collision the same/better/worse than two Taurus' each travelling at 50km/h and having a head on collision?

(Ignoring air/road friction, etc)

My view was that given the general theory of relativity, both collisions are exactly the same, but my colleagues arguement was as follows:
Energy = mass * velocity squared
and 100 squared is greater than 50 squared + 50 squared so the energy in the first collision is greater (hence a 'worse' collision).

Any thoughts??:confused:

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The best way to think of spin is not to do it three dimensionally but to use higher dimensional plains.

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For once more dimensions make something much easier :)

When it was revealed (in the Horizon sciene program, that I Sinnersis watched too ) that 10 D string theory had problems, my flatmate joked that it would be solved by adding one somewhere...

Hmm, can't edit my message. The program was Horizon, on BBC2 in the UK.

Ilkpc has been sorely missed in this discussion. He hit upon many great points. One being; there is no such thing as a vaccuum. Why build theories around a non-existant? Einstein had to disprove a "universal frame of reference" for his theories to work because none could be found. Then he creates a vaccuum in order for some of his to work... The reason your stick looks broke when you stick it in the water is due to light being slown down. It has been slown to several MPH recently, and sped up to beyond C (well waves were propagated beyond C, but its a start!). Here's a link on the latter: Gain-Assisted Superluminal Light Propagation

A book that helped me understand the quantum world, and I'm surprised it hasn't been mentioned here yet, is Gary Zukav's The Dancing Wu Li Masters. Read that before Hawkings' and Greene's excellent work and you will save yourself a lot of headaches. Just stop at that work of Zukav's and don't continue with his recent Oprah-fied Seat Of The Soul garbage.

I may be wrong but it seems that some here are quoting things about the Uncertainty Principle without understanding it. The reason it is there is that, with fundamental particles, your observing them influences them. Read the aforementioned book for an in-depth explanation. On a side note: I did read something in the past few months and I can't remember where (probably Sci-Am or New Scientist) that some were "getting around" the Uncertainty Principle. If I dig up the link, I'll post it.

I don't think that this was the link I that I referred to in the previous post, for it is a few years old. Or could it be that my internal frame of reference (subjective) for a few months is that of a few years to the outside world (objective)? Ugh... these discussions... Anyways, it is interesting nonetheless.
Quantum nondemolition measurements

I think the link I was thinking about had to do with quantum computing. It probably did refer to this series of experiments though in their use in that field.

Blacktooth, it does say in that link that the experiment is not at odds with Einstein's relativity. Frankly I didn't read the whole thing so I can't explain why. But it said that flat out in the faq.

Also, blacktooth, you say why build theories about things that don't exist. The answer is because you need some basis for the theories. Since nothing is perfect, you need hypothetical perfection, probabilities and margins for error.


neelpeel, those collisions are EXACTLY identical, but thats not due to relativity, thats Newtonian physics - momentum.

Considering the force of both cars in the 50/50 senario would cancel each other out, and some of the energy of the 100/0 impact would just be transferred to the motionless car, the 50/50 impact would probably be worse.

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Originally posted by Blacktooth
Ilkpc has been sorely missed in this discussion. He hit upon many great points. One being; there is no such thing as a vaccuum. Why build theories around a non-existant? Einstein had to disprove a "universal frame of reference" for his theories to work because none could be found. Then he creates a vaccuum in order for some of his to work... The reason your stick looks broke when you stick it in the water is due to light being slown down. It has been slown to several MPH recently, and sped up to beyond C (well waves were propagated beyond C, but its a start!). Here's a link on the latter: Gain-Assisted Superluminal Light Propagation

A book that helped me understand the quantum world, and I'm surprised it hasn't been mentioned here yet, is Gary Zukav's The Dancing Wu Li Masters. Read that before Hawkings' and Greene's excellent work and you will save yourself a lot of headaches. Just stop at that work of Zukav's and don't continue with his recent Oprah-fied Seat Of The Soul garbage.

I may be wrong but it seems that some here are quoting things about the Uncertainty Principle without understanding it. The reason it is there is that, with fundamental particles, your observing them influences them. Read the aforementioned book for an in-depth explanation. On a side note: I did read something in the past few months and I can't remember where (probably Sci-Am or New Scientist) that some were "getting around" the Uncertainty Principle. If I dig up the link, I'll post it.

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While a perfect vacuum may not exist, reasonable approximations of the relevant properties of a perfect vacuum can be calculated.

The speed of light, or any other EM wave is a function of the dielectric permittivity, and the magnetic permeability of the surrounding medium. These values are easily measured for free space, which is what we are really interested in anyway.


As for building theories around something that doesn’t exist, there is simply no way around that. Quantum mechanics is built around mathematical models and observations that are themselves unverifiable in the context of some larger truth.

This in no way invalidates the model since in this respect it is similar to everything generated by science. Science itself is based on a fundamentally flawed logic argument, and as such can NEVER deal in absolute truths. It is, however, exceptionally good at generating useful results.

Since it can only deliver useful results and not absolute truth, any theory that can continue to generate useful results is itself useful. By insisting on a “perfect” theory you are in fact searching for truth, and this is something science cannot provide.

The issue I had with the things Ilkpc was saying. He seemed to feel that because quantum mechanics could, (with great difficulty) explain most of the things that relativity explains (with relative ease) that there was no further need for relativity. While I do not dispute that QM has surpassed relativity in accuracy, in many areas, including some most of the things discussed here, it is still not as useful.

For myself, I’m an engineer, not a physicist or a philosopher. I could care less whether a theory is true or even valid. All I care about is if it works for what I am trying to do at the time. If more then one model works then I take the simplest one, it as easy as that. Given that no scientific theory can be said to be true this is by far the best approach to take IMO.

By way of a quick explanation of what I am referring to:

The scientific method works as follows. Make observations, from those observations come up with a hypothesis that explains them. Use the theory to make meaningful predictions. Evaluate those predictions through experimentation and measurement. If discrepancies are found modify the hypothesis to fit the results. Once you no longer have discrepancies the hypothesis becomes a theory.

The flaw in this method is that to prove something using it you would have to observe literally everything and conduct every possible experiment. Since this is not possible, anything generated by the scientific method can never be stronger then a theory. Science can never give you truth, and anyone seriously involved in science should always keep in the back of his or her minds.

It is also why I find it amusing when someone says something is only a theory. A theory is the strongest statement you can ever make in science. By saying something is “only a theory” you call into question everything that science generates. Do you disregard the fact that computers exist because the science they are based on is “only a theory”? Science is not perfect, but it produces results far better then any other search for knowledge man has ever undertaken.


BTW the uncertainty principle really only states that you cannot know more then a certain amount about the position and action of a given particle. The error in position multiplied (IIRC) by the error in velocity must at all times be larger then some minimum value. There are also some other spin offs like not being able to know time and frequency exactly.

The fact that measurement effects outcome is a consequence of this. Since the total error has a minimum value, if you measure either property too exactly you MUST loose some information about the other. In any experiment you conduct the behavior of the second property therefore must change if you measure the first to exactly.

We are in agreement Moridin. My point about Einstein was that he was searching for a unifying theory, so absolutes are critical here. It is beyond argument that the theories of relativity are useful. As you stated, it doesn't mesh at all with QM though which is very important if you are working in theoretical physics.

I never said that the NEC experiments (peer reviewed BTW, not a bunch of quacks) violated relativity, nor did those scientists. I even mentioned that it was waves that were propagated superluminally. I was using it to point out that the medium the light travels in is very important (a complex medium in the NEC experiment). It's a damned interesting experiment nonetheless.

Ah, I see the mis-communication now. I re-read my post and I did say "theories" when what I meant was "unification theories".

Sorry for the confusion :(

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Originally posted by Moridin
Once you no longer have discrepancies the hypothesis becomes a theory... Science can never give you truth...

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Just a picky little note here: We never insist on having no discrepancies before calling any particular model a scientific theory. Instead, a 'scientific theory' is meant to describe any existing body of observations - and accompanying set of modeling hypotheses - which consistently fit the accepted paradigm of thought in a given discipline at a given time.

Historically, there has never existed a scientific theory which did not simultaneously have several known and confirmed anomalies at the particular time it was in fashion. Such discrepancies are not only unavoidable, they are usually assumed in advance to exist, by virtue of science itself being an entirely empirical (and thus experimental) endeavor. There are always discrepancies.

While no scientific theory can ever be proven, they are nevertheless considered disproven when 1)the volume of known discrepancies becomes unacceptable, and 2)a reasonable working alternative model is found. When this happens, the old bodies of knowledge are still called theories though (albeit "old" or "outdated" ones).

Because of this, there really is no flaw in the logic of the scientific method, only a focus on experimental rather than on purely intellectual discovery methods. Any quest for 'no discrepancies' would imply a truth discovery - and since truth is not a subject of science, there isn't a 'no discrepancies' requirement before calling any given model a scientific theory.

Again, just being picky here! It seemed especially relevant in this discussion though... :cool:

russ_waters:
IMO, religion is a set of beliefs that you live by. Would you agree with this? I believe that everyone has a religion. To some people, atheism is a religion. To some people nationalism is a religion. To some people, Communism is a religion. Thus, you can't say that religion causes science to not progress. People cause science not to progress, not religion, since everyone has different beliefs.

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Yeah, elimc, I'll buy that. Its people's REACTION to and USE of religion that causes them to hold back science. I don't see that as being more than a semantic difference between what I said, but either way I understand what you are saying and agree.

Can somebody explain the right hand rule of angular acceleration? (Not the right hand and left hand rules of electric fields) What does it mean that the thrust is always toward you with counter clockwise rotation?

It was my understanding that this is a somewhat arbitrary way of defining positive and negative for the angular acceleration vecor. I'm not positive about that though. I just accepted it and used it when I needed to.