Starship Asterisk*

The tweak needs a tweak.

But on the back of everyone's mind, and it keeps cropping up in every Pioneer anomaly article I find, that the fundamental physics of our universe may need to be brought into question. Sending long-distance deep space probes gives us a huge opportunity to see if what we observe locally is the same for other parts of the Solar System. Could Einstein's general theory of relativity need to be "tweaked" when considering interplanetary (or interstellar) travel?

Why would we think, that in all of time, physics never changes?

http://www.universetoday.com/2008/04/16 ... n-gravity/

I don't think that anyone would argue that physics never changes. Certainly in the early universe physics was much different than it is today. But I doubt very much that physics has changed significantly since Pioneer 10 & 11 were launched, or since Einstien's General Relativity, or even since the Dawn of Man.

It's probably due to error in the data. That's my vote.





OR perhaps they are accelerating to escape Klingons:

Orca wrote:It's probably due to error in the data. That's my vote.

Get an egg cup, dip it in the Atlantic or Pacific. Then tell me everything there is to know, about them oceans, From what you learn, from the contents of your little Egg Cup.

You may find a few pieces missing, from your Jigsaw.

What physics have we not discovered yet. That help make the Jigsaw?

mark swain wrote:

Orca wrote:It's probably due to error in the data. That's my vote.

Get an egg cup, dip it in the Atlantic or Pacific. Then tell me everything there is to know, about them oceans, From what you learn, from the contents of your little Egg Cup.

You may find a few pieces missing, from your Jigsaw.

What physics have we not discovered yet. That help make the Jigsaw?

It's possible there is some phenomenon here we don't yet understand. But highly unlikely.

Also, your analogy really only works in terms of "knowledge of individual objects and events in the universe" rather than "the rules by which the universe functions." As far as we have observed, the laws of physics are the same throughout the universe. So while an egg cup of sea water might not tell you about dolphins, the same laws of physics apply to the water in the cup as to the dolphins. So the fact that you can't see dolphins in your cup doesn't suggest that one can't apply the same set of rules to understand them both.

Orca wrote:It's possible there is some phenomenon here we don't yet understand. But highly unlikely.

Also, your analogy really only works in terms of "knowledge of individual objects and events in the universe" rather than "the rules by which the universe functions." As far as we have observed, the laws of physics are the same throughout the universe.

There are far to many unanswered questions, surly. Newton described one type of gravity, Einstein another, Yet nobody has nailed it have they? A little infinity problem.


Funny thing is, we know even less about the bottom of the deepest oceans.

mark swain wrote:Newton described one type of gravity, Einstein another, Yet nobody has nailed it have they?

They described the same type of gravity, they simply described it in different ways, each appropriate to different conditions. Einstein's approach may be 100% correct- it certainly seems likely. Or, depending on how things go with quantum gravity (which may turn out to be something that doesn't even exist), our theories of gravity may undergo additional refinement. But it's still the same gravity, and any new theories are not going to invalidate the old ones, merely expand on them.

Chris Peterson wrote:They described the same type of gravity, they simply described it in different ways, each appropriate to different conditions.

So, as Newton's formula implies, only things with mass are affected by gravity, You would say that was correct?

Chris Peterson wrote:Einstein's approach may be 100% correct- it certainly seems likely.

This guy says different.

http://video.google.com/videoplay?docid ... 5887486158#

I like the bit where hes says : The force of gravity, still sits outside what we know.

Mark

mark swain wrote:So, as Newton's formula implies, only things with mass are affected by gravity, You would say that was correct?

Yes, I would say that is essentially true. I'd also say that there is a wide realm of conditions where Newton's treatment of gravity works very well, and can reasonably be considered "correct". From a practical standpoint, Einstein's more complete treatment is only required for a very different realm.

mark swain wrote:

Chris Peterson wrote:Einstein's approach may be 100% correct- it certainly seems likely.

This guy [Brian Cox] says different.

And he might be right. But he might also be wrong. My point was only that- so far- nobody has produced a convincing observation that contradicts General Relativity. Certainly, most physicists want to see gravity reconciled with quantum mechanics and the other forces. It seems like the Universe should have that kind of elegance. But this is a philosophical observation, not a scientific one, and the Universe is under no obligation to satisfy our sense of aesthetics.

I'm highly confident that Einstein will not be found "wrong" any more then Newton was. I agree with Cox that we are likely to develop a much deeper understanding of gravity over the next few decades. The degree to which that results in modifications to GR remains to be seen. Personally, I think most of the advances in knowledge will be in understanding gravity at a quantum level. I don't think it's likely that theory describing the behavior of gravity at cosmological scales is likely to change.

Chris Peterson wrote: mark swain wrote:So, as Newton's formula implies, only things with mass are affected by gravity, You would say that was correct?


Yes, I would say that is essentially true.

I just found some great photo's

http://csep10.phys.utk.edu/astr162/lect ... nsing.html

Chris Peterson wrote: mark swain wrote:

Chris Peterson wrote:Einstein's approach may be 100% correct- it certainly seems likely.


This guy [Brian Cox] says different.


And he might be right. But he might also be wrong.

I get the feeling, he might be both.

mark swain wrote:I just found some great photo's
http://csep10.phys.utk.edu/astr162/lect ... nsing.html

Yes, gravitational lensing is impressive. It is also one of those many independent evidence lines that supports GR (which predicted gravitational lensing before it was first observed). It is an area where you need GR to fully describe what's going on; while you can plug in the mass of a given photon and use Newtonian mechanics to predict how it will behave in a gravitational field, this turns out to produce slightly incorrect answers. Photons operate in a relativistic regime, so only GR fully describes their behavior in a gravitational field.

This guy, Dr. Brian Cox, has become my favorite speaker on modern physics. He has that ability to impart the wonder of the unknown while being able to convey essential knowledge in terms the laymen can understand. Dr. Carl Sagan had that ability, as does Dr. Neil deGrasse Tyson and even Dr. Stephen Hawking to a certain extent.

But when Brian says that Einstein was wrong, he meant it in the same sense that Newton was wrong. While Newton's equations do not fully explain gravity, they are not wrong. They are just not complete. They are very good first estimates, and for most purposes, sufficient. Likewise, Einstein's equations aren't wrong, but even Einstein realized that something was missing. In the realm of the very small (Plank time, Plank length, Plank mass), Einstein's equations break down. That is why there has been an inability to combine general relativity with quantum mechanics into a single unified theory.

Totally agree with you bystander.

Brian cox is very easy to understand. but not just that, he awakens my mind to unbelievable possibilities.

I left another thread on 'time', that he made, in open space. What Time is it? Blows me away.

http://asterisk.apod.com/vie ... 23&t=17993

It all makes for an interesting Read.

bystander wrote:Einstein's equations aren't wrong, but even Einstein realized that something was missing.

• FRANK CONSTANZA: Let me understand, you got the hen, the chicken and the rooster.
  The rooster goes with the chicken. So, who's having sex with the hen?
  
  GEORGE CONSTANZA: Why don't we talk about it another time.
  
  FRANK: But you see my point here? You only hear of a hen,
  a rooster and a chicken. Something's missing!
  
  MRS. ROSS: Something's missing all right.
  
  MR. ROSS: They're all chickens. The rooster has sex with all of them.
  
  FRANK: That's perverse.

bystander wrote:In the realm of the very small (Plank time, Plank length, Plank mass), Einstein's equations break down.
That is why there has been an inability to combine general relativity with quantum mechanics into a single unified theory.

http://en.wikipedia.org/wiki/General_relativity wrote:
<<Attempts to generalize ordinary quantum field theories, used in elementary particle physics to describe fundamental interactions, so as to include gravity have led to serious problems. At low energies, this approach proves successful, in that it results in an acceptable effective (quantum) field theory of gravity. At very high energies, however, the result are models devoid of all predictive power.

There are alternatives to general relativity built upon the same premises, which include additional rules and/or constraints, leading to different field equations. Examples are Brans-Dicke theory, teleparallelism, and Einstein-Cartan theory.

neufer wrote:

http://en.wikipedia.org/wiki/General_relativity wrote:
There are alternatives to general relativity built upon the same premises, which include additional rules and/or constraints, leading to different field equations. Examples are Brans-Dicke theory, teleparallelism, and Einstein-Cartan theory.

What about Hořava Gravity?

mark swain wrote: http://asterisk.apod.com/vie ... 23&t=17993

Yeah, I saw that and enjoyed it, immensely.

bystander wrote:What about Hořava Gravity?

What about Hořava Gravity?

You mentioned several alternatives to general relativity. I just thought I would mention what seems to be the latest attempt to associate quantum gravity with general relativity.

A Spherical Physics

I may have already said this in another post, But to me, matter seems to be like a fish out of water. At the very large scale and the very small scale, to me, matter has something in common. They both form spheres. And at incredible distances like 100,000 light years they still form spheres. And when you smash little particles at close to the speed of light you see them trying to form little spheres. The whole universe is curved? How can the whole universe be entangled to form a sphere? 90 billion light years across?

To me, its almost like matter should not be here in space/time. And somehow wants to get back to where it came from.