
#37
Sep3011, 12:50 AM

P: 141

That isn't really a good example but it might help you see the point people are trying to make. 



#38
Sep3011, 02:05 AM

P: 344

So when time shrink, the meter stick extend? And this explains that the math is correctm,  for both,  when 1 orbit of the MilkyWay is completed? 



#39
Sep3011, 04:50 AM

P: 42

Ah, alright. I just went back and reread how this thread began:
Bjarne: The answer is yes, the laws of nature would be found the same in all reference frames. However, the measurements taken of your surroundings, and thus your inputs into your equations, would be different. Because the measurement is different, your receive a different answer for your reference frame. However, because of your different reference frame, you received the right answer for you. That was actually the point of the idea... that we had spent hundreds of years making equations and laws that only worked for Earth and our reference frame. GR and SR together were a set of rules that would give the right answer even if your measurements turned out different. 



#40
Sep3011, 03:23 PM

P: 344

We can very simple multiply speed and time and get the result = distance Why can a "stranger" living in a different spacetime (caused by GR)  according to the mentioned example, not do the exact same as we can ? Why seems reality to be limit to a certain place on Earth. ? WHAT exactly should a observer that not shares our timerate then exactly do if he also want to make such speed * time calculations. ? How are the rules for him? Shall he just pretend he is moving faster as us, even though there are absolutely no reason to believe so ? Is his meter sticks really longer than ours and distance therefore shorter for him? WHAT exactly would you tell him?. I mean not only words, but how are the rules / law exactly according to the examples I have mentioned? How can such relative huge dilemma have surveyed in 100 years without anyone have wonder; what happens here? I believe we have no clue how to explain that, right ? This could be a bad sign. 



#41
Sep3011, 03:32 PM

Mentor
P: 22,000

The rules for another observer are exactly the same as for us. No pretending needed and no issue of who's measurement is "really" right  the whole point of Relativity is that both measurements are right.




#42
Sep3011, 04:01 PM

P: 344

Questions
It seems to be that we say that our reality is more real than these”out there” I mean this is also how science was in the Middle Ages,  something must have change since. I am not satisfied with words, but to know WHAT exactly is going on here. 



#43
Sep3011, 05:39 PM

P: 141

You are getting caught up in time, speeds, distances being absolute. You have to do the calculations with respect to each "observer." So you say you are moving at 250k/s you have to ask with respect to what. In your own frame of reference you aren't moving at all. In the earths you are moving at one speed, sun another,...




#44
Sep3011, 05:47 PM

Mentor
P: 22,000

If both observers faithfully follow the principle of Relativity as stated in your title and, as it requires, ensure they are clear and consistent about what frames of reference they are doing the measurements from, or measure from one and properly transform to the other, they will agree on what is happening. 



#45
Oct111, 02:45 AM

P: 344

We have a orbit and thereby a circumstance of the milkyway (MW). You can bend the orbit to a straight line. So you do have “two points”. A staring point that also is the final point when the orbit is completed. The Sun travels relative to a points of no motion, which is the center of the Milkyway. The 2 clocks are according to the example mentioned above following the exact same orbit as the Sun. The orbits of the 2 clock’s are exactly the same (for all observers). Observer A and B are doing the measurement from their own reference frame. B's clock is really ticking slower as A's clock  because B is closer to the Sun as A and therefore comparable slower as A's clock. Nothing prevent that A and B can compare time differences. Think about; how do we determinate how long 1 meter is or what the speed of light. Both obersver A and B would determinate that the exact same way, wouldn’t they? B's reality is real, as well as A's (or our) reality also are real. Therefore B's meter stick will really be shorter. We are not speaking about "illusion" but about realities. Both A and B is according to the example in the same SRreference frame, since both exactly follows the motion of the Sun, hence SR do not apply,  only GR does. Let me ask more simple and allround. Imaging you was orbiting the Sun with a meter stick 50 billion km from the Sun. I was orbiting 150 billion km from the Sun also carry a meter stick. Would both meter sticks comparable be the same length? . What I am asking is 1 meter the exact same length if a observer far away ( not affected by gravity of the Sun) could se both meter stick and also was able to compare if our meter stick did have the exact same length, so long we are different places in the gravitational field of the Sun ? Now let say that time in your orbit is 1 billion part slower for you, compared to my time rate. Would your meter stick then proportional to that be 1 billionpart longer ? (or shorter ) – or exactly the same as mine,  still seen from a observer C far away and not affected by the gravity of the Sun. I am not mixing anything but asking what is the speed and [B]distance /B] difference between A’s and B’s reality according to the example,  if any ? There must be a very simple answer to that question. If you would say there is no difference between the reality of A and B (accept time), simple math would show you a mathematical contradiction, since time multiplied with speed can impossible result to the same distance for A and B. (since time for B is shorter) So I am in fact trying to separate relative differences. Mathematical either speed or distance cannot comparable be the same. So what is the mathematical answer here? Is speed comparable larger  or is it distance that is proportional and comparable shorter (and therefore the meter stick propositional longer) ? If nothing proves that (comparable) speed is affected (and hence comparable different), and you multiply less time (for B) with the same (comparable ) speed that is valid for A,  you will get a shorter distances for B. So if you have no objection that we assume that speed is (comparable) the same for A and B,  then it is mathematical proven that distance (circumstance of the MW) for A and B NOT is comparable the same for A. If you do not agree speed is comparable the same, what is the correct comparable speed for B, ?. Yours assumption that I am mixing realities is not true. – I am ONLY comparing realities, and do in fact try to keep factors separated, by asking what the differences except time . Is speed and / or distance comparable different according to the very simple example mentioned? Please try to keep it simple. 



#46
Oct111, 02:57 AM

P: 344

Both clocks’ follows the Sun SR does not apply to the mentioned scenario. So this is not the correct answer either. 



#47
Oct111, 12:05 PM

P: 141





#48
Oct111, 02:23 PM

P: 344

That must be valid for us but also for an observer with a slow ticking clock. 



#49
Oct211, 11:26 AM

P: 141

Saying something is moving 250km/s is meaningless unless you say what it is with respect to. 



#50
Oct211, 12:06 PM

P: 51

Hope this helps. 



#51
Oct211, 04:13 PM

P: 344

I don’t know how they did that measurement. It is not with respect to “something” I believe,  but only to the center of the MW, where you have relative no motion. If we can do such measurement, other observers in the Solar system can also. But I am not sure the result for a different spacetime observer would be the same. 



#52
Oct211, 04:23 PM

P: 344

I belive many really are confused. I am not sure that the right answer exsist ? Try to be more specific and if you can try to answer some of all the questions. I seem that many have mysophobia to answer concrete, for example show the simple content of the equation for B Alle the content of the equation for A we can say we know,  A could share the same time rate as here on Earth, so it is only the stranger B,  that is the problem / challenge.
We are only discussion GR not SR 



#53
Oct211, 04:46 PM

P: 141

So are you trying to get the results from a frame of reference that is at the center of the MW galaxy? 



#54
Oct311, 07:10 AM

P: 51

1) Twin paradox. See: http://soi.blogspot.com/2011/09/twinparadox.html 2) Faster than light violates causality. See http://soi.blogspot.com/2011/09/why...causality.html 


Register to reply 
Related Discussions  
GR in all frames of reference  Special & General Relativity  7  
Concerning reference frames  Special & General Relativity  5  
Reference frames  Introductory Physics Homework  9  
frames of reference  Introductory Physics Homework  8  
Frames of reference & Inertial frames  Classical Physics  2 