Welcome to
Science a GoGo's
Discussion Forums
Please keep your postings on-topic or they will be moved to a galaxy far, far away.
Your use of this forum indicates your agreement to our terms of use.
So that we remain spam-free, please note that all posts by new users are moderated.


The Forums
General Science Talk        Not-Quite-Science        Climate Change Discussion        Physics Forum        Science Fiction

Who's Online
0 registered (), 224 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Latest Posts
Is there anybody out there?
by paul
12/07/19 03:58 AM
Top Posters (30 Days)
paul 1
True 1
Page 2 of 3 < 1 2 3 >
Topic Options
#55097 - 01/06/16 12:36 AM Re: Do orbiting bodies accelerate? [Re: paul]
Orac Offline
Megastar

Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
Originally Posted By: paul
you cant see the forces or measure the forces so you think that they are not REALLY there.

You turned this into what I believe ... I can work in many different frameworks and they all have problems. Again the function of physics is to be useful and predictive not worrying about what is believed.

The problem in classical physics framework is exactly as you have worked out you get forces you can't see or measure and the results of those forces can go to infinity or zero. Yet you have an effect that is real and observable.

To layman that may not be a problem by in physics that is unacceptable because it means we are missing something.


Edited by Orac (01/06/16 12:37 AM)
_________________________
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.

Top
.
#55098 - 01/06/16 12:37 AM Re: Do orbiting bodies accelerate? [Re: Orac]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
orac

when you are sitting in a chair and you stand up.

1) is your body applying a force that causes you to
stand?
2) if so is that force being applied against the earth
or against gravity?
3) if the earth had no gravity field would your body
need to apply a force to.

a) the earth
b) the atmosphere
c) the gravity field of your body
d) none of the above
_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

Top
#55099 - 01/06/16 12:42 AM Re: Do orbiting bodies accelerate? [Re: paul]
Orac Offline
Megastar

Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
I can't answer you questions without nominating a framework they differ markedly depending what you choose.

1.) Is the same for all frameworks .. YES

The rest depends which framework you choose.

You have agreed on the problem classical physics runs into with "hidden" forces and GR gives us a different way to look at things but it changes some definitions.

GR may not ultimately be exactly correct but it is giving us more answers with fewer "hidden" forces and you can resolve all the answers back to classical physics, so why wouldn't we use it?


Edited by Orac (01/06/16 12:47 AM)
_________________________
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.

Top
#55100 - 01/06/16 12:46 AM Re: Do orbiting bodies accelerate? [Re: Orac]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
because it means we are missing something.


what are we missing orac?
_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

Top
#55101 - 01/06/16 12:48 AM Re: Do orbiting bodies accelerate? [Re: Orac]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
The rest depends which framework you choose.


pick a framework and answer the question.
_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

Top
#55102 - 01/06/16 12:51 AM Re: Do orbiting bodies accelerate? [Re: Orac]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
fewer "hidden" forces


the only forces we are discussing are gravity and forces due
to motion.

do you require that a force actually be seen?
can you see any force at all?

tell me which force is not a hidden force?

have you ever seen the force that is the result of a
baseball bat hitting a baseball?

you have never seen a force is a truthful statement.



_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

Top
#55103 - 01/06/16 12:52 AM Re: Do orbiting bodies accelerate? [Re: paul]
Orac Offline
Megastar

Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
Originally Posted By: paul
what are we missing orac?

Go back to the must cut down version of this which is Newtons bucket argument

https://en.wikipedia.org/wiki/Bucket_argument

The curvature of the water surface of the spinning bucket makes perfect sense to anyone in the bucket. It makes absolutely no sense to someone standing outside the bucket where you ask "rotation relative to what?"

You now need to make the rotation complicit to every body in the universe and those forces must transfer INSTANTLY no matter how far away the body is.
_________________________
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.

Top
#55104 - 01/06/16 12:57 AM Re: Do orbiting bodies accelerate? [Re: paul]
Orac Offline
Megastar

Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
Originally Posted By: paul
do you require that a force actually be seen?
can you see any force at all?

Yes of coarse you can how else would you measure it. Seen does not mean human eye type stuff it means you can measure cause and effect.

Originally Posted By: paul
tell me which force is not a hidden force?

Every other force except our four fictional forces in classical physics are directly measurable. Our four problem forces in classical physics are sometimes measurable in some situations but not all.

Originally Posted By: paul
have you ever seen the force that is the result of a baseball bat hitting a baseball?

What I have never seen is a baseball fly off by itself without being able to attribute where the force came from. In your classic physics world gravity is dragging the ball down, so where is it getting the energy?

Now I need to give you a warning if we go down this path you are going to end up needing all the energy to be present at the start of the universe. This may come into conflict with your religious beliefs.


Edited by Orac (01/06/16 01:01 AM)
_________________________
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.

Top
#55105 - 01/06/16 01:03 AM Re: Do orbiting bodies accelerate? [Re: Orac]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
the reason the people outside the bucket dont understand
is because they do not understand how liquids behave and
react to rotational forces.

what has this got to do with what we are discussing?

which is how you are not accelerating while you are reading this.
_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

Top
#55106 - 01/06/16 01:06 AM Re: Do orbiting bodies accelerate? [Re: Orac]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
Every other force except our four fictional forces in classical physics are directly measurable. Our four problem forces in classical physics are sometimes measurable in some situations but not all.


lets discuss these fictional forces.

name them.
_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

Top
#55107 - 01/06/16 01:23 AM Re: Do orbiting bodies accelerate? [Re: paul]
Orac Offline
Megastar

Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
In classical physics you need to create four fictional forces. We could use term observational forces if you like, which is what we do in Russian physics, as fictional has bad meaning. The forces are real in certain frames just can't be brought back to a universal reference frame.

Centrifugal force
Coriolis force
Euler force
Gravitational force

The first three are inertial frame issues being translated back to the static global frame classic physics demands. Gravity is problematic because we don't know what causes it and it comes from nowhere and goes to nowhere.

The first three cause problem because you can't find a zero reference. For example you feel the forces if you spin on earth yet earth is spinning itself. The earth is also moving around the sun and the sun and earth moving around the galactic center. Then that whole galaxy is also moving.

Now try and construct the force with all those motions back to some stationary point in space that classical physics says is possible and I believe you are saying.

It's easy if you just use the local reference and don't ask what's it pushing against, which is how we hand wave at school level smile

By default in doing the above we just went into relativity in a rather sneaky way. However classic physics demands a global reference frame so convert those forces to a global frame. The other part of the problem is that force must also be INSTANT no matter how far away.

In case you don't know Newton's gravity law's requires instant transfer for the same reasons.


Edited by Orac (01/06/16 01:39 AM)
_________________________
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.

Top
#55108 - 01/06/16 01:44 AM Re: Do orbiting bodies accelerate? [Re: Orac]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
Centrifugal force
Coriolis force
Euler force
Gravitational force


not sure about the euler force as it only deals with
reference frames.

centrifugal force can certainly be measured.
Coriolis force can certainly be measured.
gravitational force can certainly be measured.

if a force can be measured then its not fictional.

it is a word that is used to describe an effect.

I was thinking you were going to include centripetal force
because you were saying that it was a fictional force earlier
and although the words "centripetal force" and centrifugal force are similar they do have opposite meanings as one is
the inward acting force and the other is the outward force.

some idiots still believe that there are no outward forces
in rotation.

it would be a true statement to say that there are no
inward forces in rotation because there are no inward
forces in rotation.

note: when I say outward force I mean a direction away from the center of rotation.

if there were no outward forces then centrifuges would not work.

satellites would not orbit the earth ... etc.... etc.

can you name a force that cannot be measured?

_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

Top
#55109 - 01/06/16 02:24 AM Re: Do orbiting bodies accelerate? [Re: paul]
Orac Offline
Megastar

Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
Originally Posted By: paul
can you name a force that cannot be measured?

All of those forces can only be measured by the person on that reference frame they can't be measured and make no sense to someone not on that frame. To a static person the force looks like it comes out from some point in space and disappears off at infinity with a whole pile of other infinities along the way.

That was the issue Bill G was having, Gravity can only be measured via a reference to mass. The moment we put that mass into what Bill G referred to as free fall it disappears as it's a non inertial reference frame, Newtons laws implode.

The problem is Newtons laws (classic physics lovelies) are only valid in inertial frames of reference ... that is ones not accelerating. In accelerating frames, like your rotating one, or Bill G's "free fall" you have to try and patch the laws if you want to keep them. It doesn't seem to worry you that you can't bring the forces back to static reference frame and in that regard your physics looks more and more like relativity which apparently you think is wrong and gave Einstein a spray.

In your post above you almost appear to be arguing for relativity and against classical physics and it's universal reference frame?

You can't have Newton's laws and relativity forces the two are incompatible that is what I beat Bill G over the head with.

So again I ask the question what framework are you using?

Lets give you the general definition of relativity physics .... don't confuse this with GR and Einstein
(https://en.wikipedia.org/wiki/Principle_of_relativity)
Quote:

That is, physical laws are the same in all reference frames.

Physics in non-inertial reference frames was historically treated by a coordinate transformation, first, to an inertial reference frame, performing the necessary calculations therein, and using another to return to the non-inertial reference frame. In most such situations, the same laws of physics can be used if certain predictable fictitious forces are added into consideration; an example is a uniformly rotating reference frame, which can be treated as an inertial reference frame if one adds a fictitious centrifugal force and Coriolis force into consideration.

So do you believe in relativity as described above and not classical physics? It has to be one or the other you can't have both.

There are many versions of relativity yet layman seem to think all of them are Einsteins versions.

Lets try one of the simpler versions of relativity, so I am going to give you Galilean relativity to look at which as you will see dates back to 1632

https://en.wikipedia.org/wiki/Galilean_invariance

Is that close to what you want, its a sort of fusion between Newtonian physics and relativity and is probably the closest thing to classical physics with relativity mixed in.


Edited by Orac (01/06/16 04:33 AM)
_________________________
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.

Top
#55112 - 01/06/16 07:10 PM Re: Do orbiting bodies accelerate? [Re: Orac]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
your entire post seems to give some value to reference frames
as if a reference frame has anything to do with reality.

if a man on the ISS is in free fall then the ISS is also
in free fall , both are accelerating.

the only way that you can orbit a planet is if you travel
around the planet in a circular path , and in order for
you to travel in a circular path you must accelerate away
from the straight line that your space ship wants to travel along.

can you imagine how much energy would be required to establish and maintain a orbit around the earth if the earth had no gravity?

the space ship that you were orbiting the earth with would
need to supply all of the energy for every split second of
course correction as it traveled along its orbital path and
it would have to correct its course every split second if
you wanted the space ship to maintain a precise orbital altitude for optics or whatever reason.

you may be able to say that the man inside the ISS is not
in free fall if your brain only accepts the things you can
see or feel or measure and you are in front of him seeing
that he is not falling anywhere , and you can reach out and touch him and he's not moving away from you and you could even measure his fall if he was falling , so in his frame of reference and your frame of reference he is not falling.

both of these frames of reference will give false information.

still he and the ISS are in free fall this is evident because
the ISS is not gaining or loosing altitude.

a frame of reference is just another way of thinking about or looking at a physical occurrence and has nothing to do with
physical occurrences.

so frame it any way you wish , the man and the ISS are in
free fall.


and free fall is simply put nothing more than a balance between the forces that are acting on an orbiting
object.

you keep pointing to accelerometers to somehow prove that
you are correct when in fact the accelerometers prove that
the man in the ISS is in free fall by the zero reading he
would see on his accelerometer.

he and the ISS have achieved a balance between the forces which is why he and the ISS do not move closer to the earth
or further from the earth.

why do you think the men moved when the ISS boosted / accelerated to gain velocity?

it was because the ISS was gaining velocity / accelerating
to maintain a certain orbital altitude.

but the men inside were not accelerating with the ISS
until they held onto the ISS.

and as soon as they let go of the ISS the ISS began moving faster than they were moving.

I think that you are giving waaaay to much importance to
false things such as reference frames.

its almost as if you are trying to use them as tools to
change the reality of physical occurrences.

that wont happen.














_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

Top
#55113 - 01/06/16 07:32 PM Re: Do orbiting bodies accelerate? [Re: Orac]
paul Offline
Megastar

Registered: 03/21/06
Posts: 4136
Quote:
Newtons laws implode.


within the context of what we are discussing can you point to where one of Newtons laws would implode?

my thoughts are that either your calculator , your math
or your reasoning is distressed if you have found a flaw in one of Newtons laws.

lets discuss this.

_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.

Top
#55114 - 01/06/16 10:14 PM Re: Do orbiting bodies accelerate? [Re: paul]
Orac Offline
Megastar

Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
Newtons laws ASSUME an inertial frame he defined that condition it is covered here ... read it

https://en.wikipedia.org/wiki/Inertial_frame_of_reference

Galileo had everything Relative in his physics

Newton needs to fix everything to a single position he does this

Quote:
Newton posited an absolute space considered well approximated by a frame of reference stationary relative to the fixed stars. An inertial frame was then one in uniform translation relative to absolute space. However, some scientists (called "relativists" by Mach), even at the time of Newton, felt that absolute space was a defect of the formulation, and should be replaced.

So Newton assumes some star or point or something is not moving and thus he deals with forces coming from movement as fictional.

WHY DID HE DO THIS?

The answer is energy ... Newton is all about energy what he is trying to do is exchange energy in all references.

The problem he is struggling with is if energy arises in a relative frame (that is locally) how does it relate to something else. Take a spinning weight I allow the energy in the forces to create locally but now I create another spinning weight. When I smash the two into each other how does the energy of one system relate to the other I need some common reference.

So Newton made his first law ... READ IT VERY CAREFULLY.

First law: When viewed in an inertial reference frame, an object either remains at rest or continues to move at a constant velocity, unless acted upon by an external force.

Newton is well aware his laws won't hold in accelerating (non inertial frame) he assumes that an inertial frame must exists and asks you move the calculation to there and bring the acceleration effects in as fictional forces. Don't complain to me about it ... that is what Newton did and so go complain to him. Your teacher at school probably left that bit out. Newton goes into elaborate detail about how to find an inertial frame but no layman ever bothers to read his works.

The bit layman never seem to get Newtons laws are not valid in accelerating frames they were never intended to be (AKA the 1st law). Newton isn't stupid almost any calculation in an accelerating frame is going to violate them. That is what happened to Bill G and I was curious to see if he knew why. His argument was you simply find a nice inertial frame move all the calculations to there include all the fictional forces and there you have problem solved. The sting in the tail is if there isn't at least one point in space that is stationary you aren't going to be able to use it on calculations on the universe as a whole because you can't satisfy the first law.

What happens in versions of relativity is you are going to link energy using a different reference not universal co-ordinates like Newton did. Most versions of relativity will link it thru Mass ... Einsteins version is E=MC2. That allows you to connect energies in relative frames and explains why the energy in one local system is related to another in always the same way.

There is nothing to really discuss this is all very basic, just layman never seem to get it that Newtons first law restricts where you can use the laws from ... that is it's intention by design.

So are you happy with all that, or do you still want to try and insist you can use Newton laws in an accelerating frame and we throw Newton's first law out?


Edited by Orac (01/06/16 11:35 PM)
_________________________
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.

Top
#55117 - 01/06/16 11:39 PM Re: Do orbiting bodies accelerate? [Re: Orac]
Bill Offline
Megastar

Registered: 12/31/10
Posts: 1858
Loc: Oklahoma, USA
Originally Posted By: Orac
That is what happened to Bill G and I was curious to see if he knew why. His argument was you simply find a nice inertial frame move all the calculations to there include all the fictional forces and there you have problem solved. The sting in the tail is if there isn't at least one point in space that is stationary you aren't going to be able to use it on calculations on the universe as a whole because you can't satisfy the first law.

I don't recall saying anything like that. As I recall you talked about the accelerometers on the ISS and what they would read. I clearly pointed out that they would read zero. You then took it and tried to show that I am so dumb that I can't say anything right. The fact is that I was completely correct. The accelerometers show zero acceleration. That is because they are in free fall and there are no forces acting on the separate parts of the accelerometers. You asked me to define free fall, but I don't think it is my job to teach you. You should study up on the subject and find out for yourself instead of just trying to show how smart you are.

Bill Gill
_________________________
C is not the speed of light in a vacuum.
C is the universal speed limit.

Top
#55118 - 01/06/16 11:51 PM Re: Do orbiting bodies accelerate? [Re: Bill]
Orac Offline
Megastar

Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
Originally Posted By: Bill
You then took it and tried to show that I am so dumb that I can't say anything right.

No I know you aren't dumb I was checking you understood what was going on and that a free falling frame has two interpretations and I asked a question. You answered the question with a reference to "free fall" and I asked you to define it so you could clearly see a problem.

You like the good little classic physics boffin took the normal stance on the problem but none of your classic laws will hold in that frame and you can't create a valid proof.

As I said this goes all the way back to the Newtons bucket argument and there are no laws in classical physics that will allow you to resolve this. As per Mr mach I will always be able to find a frame in which I can ask accelerating/rotating in respect to what?

Newtons answer is take a frame not on the "free falling frame" and resolve from there and you will have to introduce gravity as a fictional force in that situation which is what I was trying to make you do. That is what the Newtonian framework says you have to do via Newtons first law. This harks to what I said way back if we go much further we will need to talk about fictional forces in classical physics.

I am assuming here you will not do what Paul did and get confused with the layman definition of the words "fictional forces" or "pseudo forces". It is a translation of Newtons choice of word to fix frame references in Principia Mathematica and what it means beyond that is conjecture.

Your answer is correct in THE CLASSICAL PHYSICS FRAMEWORK with gravity injected as a fictional force that can't be measured in a free falling frame. The extension of that is you can't use a gravimeter in a free falling frame if it is using the laws of classical physics to measure gravity. You accelerate such a device up/down in any way it will miss read. Your answers on that subject totally perplexed me but lets ignore that, I am not trying to upset you and it's a side issue.

Bill G you sort of claim you believe in GR but don't find your answer somewhat problematic or that you at least need to qualify it?

I asked the question "can you measure zero force and yet be accelerating?" because I know the answer to it needs a framework and was trying to get you guys to see that.

Bill G you said and still insist ... that you can measure zero force and yet be accelerating .... NO QUALIFICATION OFFERED.

It isn't the measuring zero I am asking you to look at BUT the accelerating bit ... you focused on the wrong bit.

MY FULL ANSWER: YES in classical frameworks and NO in relativistic frameworks and for someone with your intelligence it shouldn't be that hard to know why.

The problem boils down to should I trust the accelerometer or should I trust what is inferred by classical physics laws. I am pretty sure you know what GR does and we change to "proper acceleration".

When I ask questions rather than give an answer there is usually a good reason, and yes they are often loaded smile

Most of the time what you see as attacking you is me simply asking you to consider there is a different valid answer at least qualify your response. There are heaps of things in physics with multiple answers, we can't distinguish between unless you identify the assumptions.

I have asked repeatedly can we get what framework we are using for this discussion because there are many conflicting answers to this stuff. Paul appears to be using some form of relativistic framework (no fictional forces) and Bill G is using classic physics (fictional forces) and somehow I am supposed to relate discussion to you both.


Edited by Orac (01/07/16 02:18 AM)
_________________________
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.

Top
#55119 - 01/07/16 04:13 AM Re: Do orbiting bodies accelerate? [Re: Orac]
Bill Offline
Megastar

Registered: 12/31/10
Posts: 1858
Loc: Oklahoma, USA
There you go again! I specifically addressed only the question of what the accelerometers on the ISS would measure. My answer had nothing to do with any reference frame. It works for both Newtonian physics and GR.

You may see what you say as a teaching experience. I see it as an attempt to show how much smarter you are than anybody else. If you are really trying to teach us something you might try explaining what you are trying to teach.

Bill Gill
_________________________
C is not the speed of light in a vacuum.
C is the universal speed limit.

Top
#55120 - 01/07/16 06:58 AM Re: Do orbiting bodies accelerate? [Re: Bill]
Orac Offline
Megastar

Registered: 05/20/11
Posts: 2819
Loc: Currently Illinois, USA
Bill G please look .... after your zero answer ... I said.

Originally Posted By: Orac
Now lets see if you can extend that with a bit more intelligence than Paul. Assuming you and the accelerometer are in the same reference frame, can you be accelerating if the accelerometer measures zero?

I was agreeing with you and simply wanted to extend the discussion about the zero ... and now you give us the fact that you will get a zero on two different frameworks for two different reasons ... TADA.

Apparently in trying to get you to clarify that fact which you only now volunteered you saw it as being smart. I actually alienated Paul with that comment. Really I meant the word logic rather than intelligence but I missed the translation, and Paul had far more complain about than you. He gave me a spray about it so I didn't bother addressing.

I asked you to define "free fall" because to describe it between the two frameworks is rather different isn't it. I was not being smart or cute with it.

I am happy just working with what you guys know, and am happy not insisting on answers because every physics framework is ultimately broken and I certainly can't give you a "right answer". I will give you a guarantee I will never insist you are wrong unless you violate the framework you are working in, or try and take the framework somewhere it breaks.

I now get that you thought I was saying the answer wasn't zero, when I was really looking for more about the framework hence the question rather than an answer.

We have multiple parties in these discussions, so if something comes across like above please just pull me up and ask what am I really asking. I try to consistently answer any serious question asked to me, although some test my patience with stupid questions they don't want answered. Often I am trying to frame one answer in reference to include the other party. You and Paul appear to be on vastly different frameworks, he really doesn't want fictional forces and comparing answers is therefore tricky.


Edited by Orac (01/07/16 08:04 AM)
_________________________
I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.

Top
Page 2 of 3 < 1 2 3 >



Newest Members
debbieevans, bkhj, jackk, Johnmattison, RacerGT
865 Registered Users
Sponsor
Facebook

We're on Facebook
Join Our Group

Science a GoGo's Home Page | Terms of Use | Privacy Policy | Contact Us
Features | News | Books | Physics | Space | Climate Change | Health | Technology | Natural World

Copyright © 1998 - 2016 Science a GoGo and its licensors. All rights reserved.