8
   

A speed beyond light question ^^

 
 
ebrown p
 
  1  
Reply Thu 6 Apr, 2006 12:52 pm
The term "irreducible complexity" is a term invented by Creationists as part of an attack on the science of evolution. The idea is that some biological structures are so complex that they could not have evolved from simpler structures since any difference would make the structure useless (and thus it would not be selected by evolution).

This term is not only scorned by most scientists-- it also has nothing to do with the discussion on Physics that we are having.

Excuse my crankiness, the attacks on science by people who haven't even taken the time to master the science they claim to be able to refute are very annoying to many of us.

But these problematic attacks are generally limited to biology.

The laws of mechanics relating to how objects act in gravity is very well understood and they well explain the motion of objects as observed both in and outside of the galaxy.

The "effect" of weightlessness that is experienced by astronauts in the training aircraft is the same. The astronauts are simply falling-- at the same rate as the plane is falling.

While they are weightless, the astronauts in the plane are on the same trajectory they would be on if the plane didn't exist-- actually in this case that's not exactly correct because of wind resistance. Gravity affects the passengers the same way it affects the plane (air would act differently).

But the plane is "falling" and the astronauts are falling and so they don't experience any effect from the Earths gravity with respect to the plane.

This is the same as the astronauts in the Space Shuttle orbitting the earth, or us on the Earth orbitting the sun.
0 Replies
 
spendius
 
  1  
Reply Thu 6 Apr, 2006 01:24 pm
Okay E-

Are gravitational effects from outside the solar system detectable?

What I'm thinking is that the earth isn't a single object.It is a composite of atoms etc.Likewise a distant galaxy is a composite and some look like single objects to us (am I right?).Is it the case that the atoms and molecules are what exert gravity and that they themselves have these forces?

I think the term "irreducible complexity" might have been invented by Creationists but the idea wasn't.I seem to remember Copernicus using different words which essentially mean the same thing.And others.

Quote:
The laws of mechanics relating to how objects act in gravity is very well understood and they well explain the motion of objects as observed both in and outside of the galaxy.


But what about the total balance that keeps everything in position.If a distant galaxy liquidated would everything shift a little?
0 Replies
 
ebrown p
 
  1  
Reply Thu 6 Apr, 2006 01:56 pm
Quote:

Are gravitational effects from outside the solar system detectable?


Yes, in a couple of ways.

First we detect gravitational effects by looking a how objects we observe in the area react. If you see a bunch of visible objects moving in a certain way, you can make deductions about what is aroung. (There is some mystery around the issue of "black matter" in which they are seeing effects from gravity that imply that there is something there we can not see).

We even make testable predictions about what we expect to measure from other galaxies with our understanding of gravity. In this case it involves looking at light waves and comparing it to what we expect to see. It is pretty cool stuff.

Recently there has been research on gravitational waves. I must admit that other than a broad overview as part of coursework, I don't know much about these... other than work is being done detecting them.

Quote:

What I'm thinking is that the earth isn't a single object.It is a composite of atoms etc.Likewise a distant galaxy is a composite and some look like single objects to us (am I right?).Is it the case that the atoms and molecules are what exert gravity and that they themselves have these forces?


Absolutely correct. This was one of the brilliant accomplishments of Isaac Newton. He was able to use calculus (which he invented (contemporarily with another who disputed his claim)) to simplify the problem.

Physics simplifies natural phenomina into mathematical models that can accurately predict how objects will act. In the example of the Earth, the model involves calculating the strength of gravity by using the distance from the point at the center of the earth and the mass of the earth (ignoring its size).

Newton showed mathematically why this model gives the exact same answer as if you figured out the gravitation force for all the single atoms. He took a complex interaction and reduced it to a simple one.

This technique is powerful because it works. We can launch a satellite and predict its orbit, how much fuel we need and how long it will take to go around each time. All of these calculations are based on Newton's simplification-- you don't have to know every single atom... just the distance from the center of the group of them, and the mass.

Ironically the point of all of this is that this is an example where the complexity can be reduced.

I don't know of the Copernicus quote you are referring to. I would be interested if you could find it.
0 Replies
 
Steve 41oo
 
  1  
Reply Thu 6 Apr, 2006 01:59 pm
how about an answer to my little ABC question ebrown?

Dont get me wrong, I am completely on your side regarding the absurdities of irreducible complexity, intelligent design, and the irreducible intelligent complexity of Spendius, who for all I know is still orbiting the sun.
0 Replies
 
Steve 41oo
 
  1  
Reply Thu 6 Apr, 2006 02:07 pm
ebrown_p wrote:
...This was one of the brilliant accomplishments of Isaac Newton. He was able to use calculus (which he invented (contemporarily with another who disputed his claim))
Leibnitz
0 Replies
 
ebrown p
 
  1  
Reply Thu 6 Apr, 2006 02:11 pm
Quote:
Supposing you take three masses and line them up A B C. Suppose A is by far the most massive, C next with B of relatively insignificant mass. There will be a force pulling B to A and a lesser force pulling B to C. The net force is deduced by subtraction. Now arrange them A C B. The net force on B is the addition of the AB and CB forces. Agree?


Yes I agree, if the objects A, B and C are fixed. (i.e. prevented from moving relative to each other.)

If they are not attached, they will accelerate towards each other (this either means they will move toward each other, or start orbiting each other).

In this case, the interaction between B and C have absolutely nothing to do with the existance of A. In other words C will act (move) relative to B the same way whether A exists or doesn't exist.
0 Replies
 
spendius
 
  1  
Reply Thu 6 Apr, 2006 02:15 pm
E asked-

Quote:
I don't know of the Copernicus quote you are referring to. I would be interested if you could find it.


I think it was in Koestler's The Sleepwalkers but I've seen the idea a good few times.It boils down to "unknowable mystery" and Darwin mentions that a few times.

The asymptote of knowledge, which has got to the point,similar to that an athlete gets to,where a small increase requires inordinate effort.It is in that zone that the religionists posit God.Creationists are actually a side issue.One of any number of "revelations".A sociological matter really.

The obvious fact,to me at least,is that bridging the asymptote is impossible but I'm all for trying for practical and possibly psychological reasons.But it wouldn't be practical to bankrupt the system or to run out of time.

Unless the asymptote is breached somebody is going to posit intelligent design in some form if only for opportunity's sake.After that it's an "education" problem.

Would you not agree?
0 Replies
 
Steve 41oo
 
  1  
Reply Thu 6 Apr, 2006 02:35 pm
ebrown_p wrote:
Quote:
Supposing you take three masses and line them up A B C. Suppose A is by far the most massive, C next with B of relatively insignificant mass. There will be a force pulling B to A and a lesser force pulling B to C. The net force is deduced by subtraction. Now arrange them A C B. The net force on B is the addition of the AB and CB forces. Agree?


Yes I agree, if the objects A, B and C are fixed. (i.e. prevented from moving relative to each other.)

If they are not attached, they will accelerate towards each other (this either means they will move toward each other, or start orbiting each other).

In this case, the interaction between B and C have absolutely nothing to do with the existance of A. In other words C will act (move) relative to B the same way whether A exists or doesn't exist.
You seem to be saying that because they object orbit each other, the forces acting upon them dont apply. I say that its the forces acting on them that cause them to orbit in the first place.
0 Replies
 
ebrown p
 
  1  
Reply Thu 6 Apr, 2006 02:52 pm
Steve, You are asking the right questions, and you are edging me toward Einstein's General Relativity (I am not sure if we want to go there)

The fact is that because the objects orbit each other, the forces acting on them don't apply. However, I don't think Newton would have stated it this way, or anyone else before Einstein came.

However, make me make an argument without Relativity- using only what Newton knew. I am afraid that without a much longer discussion, you will have to trust me (or other, smarter Physicists than I) on the claim that Relativity makes that your statement you gave incredulously is, in fact, scientifically correct.

But let me stick with Newton.

The goal is to create a simplified model that accurately predicts the behavior of real objects. The calculations we make to predict the force of gravity involve taking the mass of the Eartch and the distance from the center of the Earth.

Another person may say that what you are really doing is figuring out the distance and mass of each tiny atom of matter in the Earth and added them all together (taking into account the direction as vectors).

Strangely enough, you get the same answer either way... and so we say that they are both accurate models (and one is much easier to use).

So if the question is, will an extremely accurate scale measure a an extremely smidgeon of lower force from when you are facing the Sun as from when you are facing away from it due to the gravity of the Sun... the answer is no.

This is certainly true if the scale is a bathroom scale or a spring scale. Because it is certainly accelerating the same way toward the sun as you. For the same reason that if you tape a scale to the bottom of your feet and then jump off a cliff (neglecting the wind) it will read zero while you are falling..

It is certain that even an infinitely accurate extrememly precise scale will read zero difference.

There are a couple of different ways to explain this.

(to be continued later...)
0 Replies
 
Steve 41oo
 
  1  
Reply Thu 6 Apr, 2006 03:14 pm
ebrown_p wrote:
The fact is that because the objects orbit each other, the forces acting on them don't apply.
no sorry flatly disagree with this. Its the forces acting on bodies that cause them to orbit. The forces dont magically disappear once they start orbiting.
0 Replies
 
ebrown p
 
  1  
Reply Thu 6 Apr, 2006 03:26 pm
You can disagree if you want. Actually this discussion is quickly losing interest for me, and I have spent way to much time typing things that you could learn (and disagree with) by reading a Physics book.
0 Replies
 
spendius
 
  1  
Reply Thu 6 Apr, 2006 03:27 pm
E wrote-

Quote:
Steve, You are asking the right questions, and you are edging me toward Einstein's General Relativity (I am not sure if we want to go there)


Hey E-I do.

This is quite fascinating.

Don't bother if I jump in with something daft. I have an idea what inspired Einstein to begin with.
0 Replies
 
ebrown p
 
  1  
Reply Thu 6 Apr, 2006 03:27 pm
<<ebrown heads back to get abuse in the Politics forum>>
0 Replies
 
Steve 41oo
 
  1  
Reply Thu 6 Apr, 2006 03:47 pm
spendius wrote:
E wrote-

Quote:
Steve, You are asking the right questions, and you are edging me toward Einstein's General Relativity (I am not sure if we want to go there)


Hey E-I do.

This is quite fascinating.

Don't bother if I jump in with something daft. I have an idea what inspired Einstein to begin with.
ok I'll go for it...

your idea being what exactly Spendi?

[I think ebrown has gone off back to politics because he realises he's losing the gravity battle]
0 Replies
 
ebrown p
 
  1  
Reply Thu 6 Apr, 2006 03:55 pm
Any reasonable discussion will start with the train thought experiment that I offered (and no one accepted).

This is where Einstein started.
0 Replies
 
hingehead
 
  1  
Reply Thu 6 Apr, 2006 04:10 pm
ebrown_p wrote:
Quote:

Are gravitational effects from outside the solar system detectable?



Not to mention observations of stellar objects acting as 'gravitic lenses' for objects emitting light 'behind' them (relative to us).

I tried to read all the guff that's gone on here because I asked the question about whether we weigh more during the day than at night before Steve (go back to page 2, your honour) but I think I can answer it myself: you do weigh more during the day but the difference is incomprehensibly small because the attraction between masses (ie gravity) is equivalent to the product of the masses involved divided by the square of the distance between them.

I saw that bit about zero gravity/micro gravity. Did anyone that mass, any mass, has gravity - therefore zero gravity can't exist if you have an observer or are using masses to experiment with zero gravity.

Also I think steve mentioned astronauts training for zero g in planes (the vomit comet). The plane just free falls to earth and relative to the plane the astronauts are weightless (ie their mass isn't drawn to any particular surface, well, not noticably anyway.)

You guys really lost me with irreducible complexity discussion. ADD I guess.
0 Replies
 
ebrown p
 
  1  
Reply Thu 6 Apr, 2006 04:16 pm
Quote:

you do weigh more during the day but the difference is incomprehensibly small because the attraction between masses (ie gravity) is equivalent to the product of the masses involved divided by the square of the distance between them.


I am quite sure that this is incorrect. There is exactly zero difference because of your acceleration (with the Earth) toward the Sun.

This is certainly true under General Relativity. The best way to explain my case is to start with the train exmple at a constant speed, and then start thinking about what happens when we accelerate the train.
0 Replies
 
hingehead
 
  1  
Reply Thu 6 Apr, 2006 04:25 pm
I think the train is a dud analogy for this problem.

I agree that the affect of the acceleration of the earth is unchanged and can be ignored - I was referring to the fact that at night you are further from the sun and therefore the attraction between your mass and the sun's is reduced (by the square of the diameter of the earth).
0 Replies
 
spendius
 
  1  
Reply Thu 6 Apr, 2006 05:15 pm
Steve wrote-

Quote:
your idea being what exactly Spendi?


Well Stee-I've read a fair bit about the man who altered the whole course of human history and I came to the conclusion that he was 100% masculine.

Being a bit inclined that way myself the idea that what things look like if you are somewhere else or going at a different speed is not all that difficult to eventually comprehend.With constant practice I mean.

Transferring such an idea to a train with a headlight is a technological matter and if,by letting it run as far as you can make it run,you can become a star looking like Al looked,you are going to have a go.
0 Replies
 
crayon851
 
  1  
Reply Thu 6 Apr, 2006 05:23 pm
this is kind of off topic, and I'm not really educated in the area of science, so spare me the criticism.

When you are accelerating you often feel colder right? What exactly causes this change in temperature when you are moving in say a car, or when you have the fan turned on and the created wind is cooling you off. How does this work ?
0 Replies
 
 

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