Faster than light???????

[MiR]

So, here's the map
(please click for higher resolution):

beispiel.png

I think what Michael may be suggesting is that the photons would pass each other at a realatibe speed of twice the speed of light (like 2 cars traveling at 60mph in opposite directions have a relative speed of 120mph), however this does not break any physical laws.

Very good example, thanks CC.
Of course; the speed of the two lightwaves is the same.

For the lightwaves let me take two trains with a million waggons each (simulating the waves). Both are stationed at NewBornStar-City.

Train A goes to EP-Town. Train B to E-Town. Each train with a speed of 120 km/h. The Towns are in opposite directions with the same distance from NBS-City. NBS-City is in the middle. And the two trains simulate the two lightwaves...

Every officer would clock each train at 120km/h. That's right. And each astronomer would clock the speed of the two lightwaves - in my examplemap - at ~ 300 000km/s.

Well, now comes the math teacher; he provides his students with the task: What is the speed between the two trains? 240km/h shouts little Albert immediately...

And now, I ask myself and you: What's the speed between the first photon of Lightwave A (please look at the map) and the first photon of Lightwave B. If both reach their target planet at the same time? This value must be higher than lightspeed! Not the lightspeed itself. (I already told you so - it's only a mathematical option/calculation.)

If this question is solved I can go on with another task...

Regards
Michael

[t00fri]

Michael,

if you read my CelestialMatters answer to your above exoplanet example carefully, it also contains the reason why your conclusions of (2x speed of light) were plain wrong.

Already in 2003 I explained the essence of the argument in this forum to some mathematical detail:

viewtopic.php?f=7&t=3319&start=9

and then again in 2008 with somewhat different words:

viewtopic.php?f=4&t=11959&p=102179&hilit=relativity#p102179

If you want to really understand what is going on, you NEED to take >=15 minutes and something to write. After reading carefully what I wrote in 2003 and|or in 2008, you will be able to derive the famous frame transformation laws of special relativity yourself (time dilatation and length contraction). It just requires some elementary high-school math along with an understanding of Einsteins two basic principles of Special Relativity (that I precisely recalled in my 2003 post). In the lower half of my 2008 post I already gave the crucial hints of how to arrive at the explicit solution for the frame transformations that respect the principles of Special Relativity...

A crucial aspect of the frame transformations in special relativity is that unlike classical mechanics also time is transformed between moving frames! In Newtonian mechanics there is only ONE time that ticks the same in all frames...

Learning by doing is essentially the only way to understand things in physics...

After doing this simple "homework" yourself, I suppose you will NOT continue assuming that within special relativity

...there must be still a possibility in our - virtually unexplored - universe. Just maybe a mathematical solution with an option opened to be faster than light.

Fridger

[MiR]

Fridger,

Thank you for these valuable sites. Give me some time and I will read the contents very carefully.
However, I can not promise that my math skills are sufficient, or what is left of it ...

Thanks for your patience
Michael

[t00fri]

If one does some homework with special relativity kinematics, one also learns that
now velocities don't add linearly anymore:

Code: Select all

Special Relativity:             

v = (v1 + v2) / (1 + (v1 / c) * (v2 / c));                         (1)


(One-dimensional case for simplicity, with v1, v2 being velocities and v being the
resulting velocity)


The reason is that normal velocities do not transform covariantly (i.e. like a 4-vector)
under a Lorentz frame transformation! They do add linearly in the Newtonian mechanics limit, though:

Code: Select all

Newtonian Mechanics (v1,v2,v << c):

v = v1 + v2                                                      (2)


Hence in examples like the previous ones, this is often forgotten and wrong results are obtained.

As apparent from formulae (1), in the limit of low velocities, v1 << c and
v2 << c, the denominator of formula (1) approaches 1 and Newtonian linear velocity addition, v = v1 + v2, is recovered!

Next, let us examine formulae (1) and (2) in the extreme, relativistic case when
v1 = v2 = c (speed of light)

When the inappropriate formula (2) of Newtonian mechanics is used,
you get

v = 2 * c > c ( Aha! I have seen that before, somewhere )

Using instead the correct addition law (1) of special relativity, you get
correctly

v = (c + c) / (1 + 1) = c

Learning by doing .
@Michael: I had hoped you'd manage to derive formula (1) yourself ...

Fridger

PS:
If instead of velocities v one introduces the so-called rapidities y via
v = c * tanh (y), v1 = c * tanh (y1), v2 = c * tanh (y2),
you can easily show from the properties of the hyperbolic tangens (tanh)
that the relativistic formula (1) implies that rapidities (NOT velocities!) add linearly:

y = y1 + y2

Remember also that always |tanh y| <= 1 , no matter how large the rapidity y is!
Hence the parametrization v = c * tanh(y) is appropriate, since it implies automatically that |v| <= c.

[MiR]

v = 2 * c > c ( Aha! I have seen that before, somewhere )

Ha ha, yes, I almost suspected, that this simple linear solution cannot be true. But I was hoping for a math-explanation, with which I can better understand the factor "time" in this context...

Learning by doing .
@Michael: I had hoped you'd manage to derive formula (1) yourself ...

Just deriving formula wasn't the problem; but I'm still reading the pages and try to understand how and why...

Michael

[MiR]

I'm still not convinced, that there is nothing in our universe, which is faster than light.

So, here my second point of criticism:

The rate of expansion of the universe immediately after the Big Bang; > already 100 years after the Big Bang the expansion of the universe is six times larger than our Milky Way (~ 100.000LY).

Consequently, there must exist one - as already mentioned - at least mathematical option, with which we can do a calculation that can handle a higher speed than that of light.

The thread "3, 4, and Extra Dimensions - General Discussion" is very interesting. But it seems to me that it is "Middle" started ...? Too bad that this Dikussion was conducted in 2003. Unfortunately, I miss some of the panelists now...?

So, Thank you for this

Michael

[t00fri]

I'm still not convinced, that there is nothing in our universe, which is faster than light.

So, here my second point of criticism:

The rate of expansion of the universe immediately after the Big Bang; > already 100 years after the Big Bang the expansion of the universe is six times larger than our Milky Way (~ 100.000LY).

Consequently, there must exist one - as already mentioned - at least mathematical option, with which we can do a calculation that can handle a higher speed than that of light.

The thread "3, 4, and Extra Dimensions - General Discussion" is very interesting. But it seems to me that it is "Middle" started ...? Too bad that this Dikussion was conducted in 2003. Unfortunately, I miss some of the panelists now...?

So, Thank you for this

Michael

Michael,

for a better understanding of questions related to the BigBang, you do need to know first the basics of GENERAL Relativity (GR). A naive application of special relativity may give totally misleading results in this case. Remember your above incorrect "v = 2*c example", where you have seen already that it is paramount to always use the appropriate framework!

GR is not easy to understand, certainly requires advanced math and theoretical physics knowledge AND some quiet time for intense personal studies.... A few lines of bla bla in a post are totally inadequate in this case, while being time consuming for the writer.

In a BigBang context, you first need to understand how to properly define a (co-moving) distance in an expanding Universe that is consistent with GR. That's already a tricky business!

In GR all frames of reference including spinning and accelerating frames are treated on an equal footing. In special relativity accelerating frames are different from inertial frames, which makes a discussion of acceleration confusing within special relativity! In the latter, velocities are relative but acceleration is treated as absolute. In GR all motion is relative. To accommodate this change, GR has to use curved space-time. In special relativity space-time is always flat. etc...

In a BigBang context, you must be familiar, e.g. with the concept of a metric, understand geodesics, event horizons and be able to apply the Einstein equations to the Friedmann-Robertson-Walker metrics, etc.

Also, it is crucial that you know how the BigBang has to be viewed??
"Nasty" test question: in which part of the Universe did the BigBang happen?

Altogether, I can assure you that there is no problem to properly understand your above example. No clashes whatsoever with v < c.

Fridger

[Chuft-Captain]

"Nasty" test question: in which part of the Universe did the BigBang happen?

Can I answer this one? ... Every part?

[t00fri]

"Nasty" test question: in which part of the Universe did the BigBang happen?

Can I answer this one? ... Every part?

Michael,

what do YOU think about CC's crazy answer?

Fridger

[MiR]

Fridger,

You are a capacity, so I trust you in these - physically relevant - things...

GR is not easy to understand, certainly requires advanced math and theoretical physics knowledge AND some quiet time for intense personal studies.... A few lines of bla bla in a post are totally inadequate in this case, despite being time consuming for the writer.

I'm sorry; but these were my questions since years. And I've read a lot of related papers - but for laypersons (and without an answer, though). Also "The first three minutes" by Steven Weinberg; some books by Albert Einstein, too. (But I must confess, I was - and I am - still more interested what concerns to his philosophical, ideological considerations.

In a BigBang context, you must be familiar, e.g. with the concept of a metric, understand geodesics, event horizons and be able to apply the Einstein equations to the Friedmann-Robertson-Walker metrics, etc.

oh, please stop now; it's enough...

Also, it is crucial that you know how the BigBang has to be viewed??
"Nasty" test question: in which part of the Universe did the BigBang happen?

Oh, I didn't wrote "I know"; I'm just surprised...

I agree with CC. The Big Bang isn't an explosion. But what does it matter? (in this case of question)
Whether space exploded or expanded like soapbubbles...?

Nevertheless it happened faster than the speed of light

Michael

[Cham]

An interesting paper which gives a possible explanation of the neutrino results (non-inertial effect on clock synchronisation) :

http://arxiv.org/pdf/1201.4147

If this explanation turns out to be true, then the neutrino experiment will turn out to be another success of special and general relativity !

[MiR]

In a BigBang context, you must be familiar, e.g. with the concept of a metric, understand geodesics, event horizons and be able to apply the Einstein equations to the Friedmann-Robertson-Walker metrics, etc.

oh, please stop now; it's enough...

Sorry, Fridger, the second "Smiley" was wrong. (It should be this one: , It's now corrected). This sentence was not meant too serious.

Regards
Michael

[t00fri]

In a BigBang context, you must be familiar, e.g. with the concept of a metric, understand geodesics, event horizons and be able to apply the Einstein equations to the Friedmann-Robertson-Walker metrics, etc.

oh, please stop now; it's enough...

Sorry, Fridger, the second "Smiley" was wrong. (It should be this one: , It's now corrected). This sentence was not meant too serious.

Regards
Michael

Never mind, Michael. I actually thought your original smileys reflected quite realistically that a solid understanding of these required, basic notions of GR implies quite a tedious learning process...

Fridger

[John Van Vliet]

--- edit ---

[t00fri]

new findings

"BREAKING NEWS: Error Undoes Faster-Than-Light Neutrino Results"
http://news.sciencemag.org/scienceinsid ... tml?ref=hp

The experiment will need to be repeated

While I had heard this rumor about a loose connection of a fiber optics cable to a critical GPS receiver already some days ago over lunch in my laboratory, it has not yet been confirmed by the OPERA collaboration. Neither at CERN nor on the OPERA Website one finds a respective comment (which is by no means surprising). Anyway, it's good to wait until there is an official statement.

Fridger

[PlutonianEmpire]

new findings

"BREAKING NEWS: Error Undoes Faster-Than-Light Neutrino Results"
http://news.sciencemag.org/scienceinsid ... tml?ref=hp

The experiment will need to be repeated

Depressing.

[Cham]

Two interesting articles on this :

http://www.nature.com/news/flaws-found- ... nt-1.10099

http://physicsworld.com/cws/article/news/48763

[Cham]

Another one :

http://www.nature.com/news/timing-glitc ... im-1.10123

[Guckytos]

Well, it's Science.

If you find something that looks contradicionary to the up to then accepted theories you have to check and recheck your results and everything you used for achieving them. And after you have done that you have to find at least one someone else who can reproduce your results with other hardware in another place. Better if more someones can verify your results.
Well of course if you are completely puzzled you ask your collegues to check if what you found can be true at all.

And only then you can start to formulate from the results a new theorie that explains the nature of what you found. And this new theorie is also only valid as long as nobody finds proof of a kind that contradicts your theorie.

The whole thing just shows that the massmedia without having any idea of the underlying processes only grab what they think they understand and then start crying out loud "Sensation!!!". And if afterwards the scientific process finds that the sensation was just an error in the hardware, the science is blamed because the media made fools out of themselves again (something that can't happen according to the 1st law of the media ).

It just shows that science is a laborous process.

To be a believer is much easier, you just have to believe! And if there is a new prophet you like more, just adapt your beliefs. No hard work necessary.

[t00fri]

Well, it's Science.
...

The whole thing just shows that the massmedia without having any idea of the underlying processes only grab what they think they understand and then start crying out loud "Sensation!!!". And if afterwards the scientific process finds that the sensation was just an error in the hardware, the science is blamed because the media made fools out of themselves again (something that can't happen according to the 1st law of the media ).

It just shows that science is a laborous process.
...

Christian,

I have been closely following the "speedy neutrino" case from the day of its first announcement on Fri Sep 29, 2011. See also my CM thread that has 5300 hits meanwhile :
http://forum.celestialmatters.org/viewtopic.php?t=416

I did actually attend the announcement talk at CERN, and we still talk almost daily about this experiment among colleagues over lunch. A Prof. colleague of mine and her group being members of the OPERA collaboration, did not sign the first paper on Sep 23 2011, because they were not convinced initially. They signed the final publication, however, that contained many more checks.

This experiment was not easy at all and there is a huge amount of places where something could go wrong without being noticed easily. As the OPERA group emphasized, the announcement on Sep 23 was made because they were stuck after testing and testing for > 6 months after the results had been obtained. They argued that hopefully new ideas/suggestions might come from within the scientific community if they went public...Another reason for going public was that such a sensational rumor will always leak out after a while.

In any case the experiment will be repeated in May, as announced a few days ago by the Director General of CERN ( -> CM). This already indicates that the situation is more complex than: "bug found, experiment wrong, basta!" One reason for a second go is that meanwhile, there is not just one bug, but actually THREE. Two of the three hardware bugs will actually lead to an increase of the neutrino speed while the faulty glas fiber cable decreased it after correction.

Anyway, I don't think that this time the media were guilty in any way. It is rather the potential "earthshaking" implications, if neutrinos were to travel at superluminous speed. In the first few months after the announcement, I counted about 10 incoming papers / day concerned with "speedy neutrinos", mostly by theoretical physicists.

Fridger