imatfaal

I'm sure I have read somewhere from a reputable source, that the Lense Thirring effect was detected by a Satellite of sorts before the highly precise GP-B confirmation.

I think Juno is gathering information as we type. Not sure I know of another one tasked to gather information about this phenomenon

https://en.wikipedia.org/wiki/Juno_(spacecraft)

If there is already a completed set of observations then it will be found at Clifford Will's site which I linked above

From this article we can expect data set in October this year

https://arxiv.org/abs/1302.6920

A rope will make waves as long as the tension keeps it off of the ground.

 

My null hypothesis indicated that I believed such a lightweight string would not make waves because the air resistance would damp them out.

 

It also made a second wave -- that was heard but not seen.

 

I see that this is not exactly "pioneer science".

 

Now what I need is a way to measure the tension and a way to measure the time.

Measure tension - use an A-frame. String attached to apex. Legs angled towards fixed fencepost Weight attached to cross-bar. Angle of frame WRTo ground varies tension in string. Won't give you absolute value in SI units but a bit of trig will give you very nice relative values for different angles

Measure time - you got a watch with a second hand? Or much better a smartphone with video. Download Tracker and use serious tools to get timings and shapes of waves - its free and pretty easy to use

Mantraphilter has been banned for a combination of reasons; hijacking, abusing staff, and a request for us to "kick him off this site for good"

My advisors on Science Forum are right: Instead of just speculating, I should DO some physics thing and record what happens...

Actual empiricism is always good. But you must be careful that your method and observations are able to disprove your null hypothesis

...I didn't have enough rope to to the rope wave thing, but, BEHOLD! here is this stick with builder's nylon twine wound on it. I measured off eleven meters of it, made loops ten meters apart, hung one end on a fence post and held the other end in my hand, hanging nearly to the ground.

 

I even wrote a "null hypothesis": This lightweight stuff isn't going to make waves.

 

It didn't. Not just loosly hanging like that. All it made was a parabola.

....

Behold what?

What was the method used to test the null - did you just hold a piece of string?

And the shape it made was a catenary (or close to) rather than a parabola. See a scientist would either have looked that up (and given references) or experimented themselves - what they would not have done was give a bald assertion because that could have been culpably wrong and it is.

[latex]y = a \cosh{\frac{x}{a}}[/latex]

rather than [latex] y=ax^2+bx+c [/latex]

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

So I took a step backward. The string made almost a straight line. But it made a wave. Not having a way to time it, I estimated the wave went the ten meters in less than a second. Not only that, it reflected back my my hand and then back to the fence. And back. And back. And back. The wave was plainly visible TWELVE trips -- well, anyway, six round-trips.

 

Hot DOG! I am doing science! Seventy-five years old and doing science fit for a six-year-old.

 

Oh. 7,000 feet above sea level. Eighty degrees Farenheit. Zero wind. Waves going east and west. Clear blue sky. No local traffic. Moderately-curious horse looking at the whole business.

 

I repeated the exercise several times with the same results.

So do you consider that your results show that the null hypothesis is not true?

VIRGO is running: http://ligo.org/news/index.php#triplelock

News from today! Great Spot.

But the event horizon is not a surface.

It is a mathematical construct.

By definition, the radial distance at which light/information can no longer escape to the observable universe as a result of gravity or space-time curvature. And this happens at equivalent gravity or space-time curvature.

As a result, the event horizon is dark, and we lose all information regarding the former matter other than mass/energy, charge and ang. momentum.

( at least until Quantum Gravity Theory tells us differently )

Sorry about moving this.

Not sure I agree with the content - should have read it properly the first time then a) I would not have mistakenly moved it and b) would have responded.

Surface Gravity - ie gravity of a black hole when at Event Horizon is not constant and varies with the size of the black hole. If we dente surface gravity as g then

[latex]g=\frac{1}{m} \cdot \frac{c^4}{4G}[/latex]

It is inversely proportional to mass and thus to radius - which in my layman's mind makes little sense. I can almost rationalise it thus; the curvature needed for there to be no exit can be mild (low gravity) within a big black hole but within a smaller black hole that curvature (and thus gravity) needs to be greater. In utterly simplistic analogistic terms that I cannot believe to be true - you can draw gentler curves wholly within a big circle than you can within a smaller one

...

@imatfaal

I thought I had posted #7 as a response to Janus on the other thread about escape velocity at the event horizon ( BH question ). As it makes little sense here, could you please move it back ?

Apologies. Done

Mathematically: Your third equation is a perfect representation of "why not"

Logically: you could create more and more extreme examples. Your system would mean that: An absolute change has a greater and greater effect on the total population as the size of the population which has been changed diminishes - this is clearly logically flawed and can be shown by taking to absurd/extreme lengths. The numbers of people in my office has decreased by 66% today - the number of people in the rest of the world has decreased by .0001% therefore the number of people in the world in total has decreased by 66.0001%.

A 20% change in one population plus a 30% change in another population cannot be added to give a 50% change in a total population

Anything actually crossing the EH, could emit a photon directly radially away: A valid point though made by another, is that we cannot see this from a remote frame of reference...In fact we see nothing cross the BH EH...We don't even see a BH form! as far as I know for the same reasons.

Which said action would change the mass-energy of the BH - changing the position of the EH.

On another tack:

From a local inertial frame the photon must travel at c, there is no frame of the photon (regardless to your comment above that "every frame of reference is as valid as any other frame" - if you posit an inertial frame in which the speed of light is not locally c then you have contradicted one of the postulates of einstein's relativity and henceforward you cannot rely on the calculations of relativity), and for a distant accelerated frame (ie someone being held in position a distance away) the photon will either be redshifted to obscurity (but still moving) or by your claim will never reach them. So in what frame does it hover

Final questions:

What is a stationary photon - ie one not travelling through a medium at the local speed of light, what is its frequency if both c and lambda equal zero(undefined?), what is its energy from planck's equation if frequency is not clear

The special case of a photon emitted directly radially away, occurs just on the EH.....

http://casa.colorado...isappearingview

As far as I know HR as generally accepted, occurs just this side of the EH, in particle pair creation event, where the negative falls in and the positive escapes to become real.

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

extract:

Hawking-Zel'dovich radiation^[1] is blackbody radiation that is predicted to be released by black holes, due to quantum effects near the event horizon. It is named after the physicist Stephen Hawking,

"As far as I know HR as generally accepted, occurs just this side of the EH, in particle pair creation event, where the negative falls in and the positive escapes to become real." This is very much a heuristic (ie not really true) explanation - the reality is vastly more recondite but I am not sure the details matter.

But if the leeway for photon hovering is that small (ie that a particle/anti-particle pair are created with a separation beyond its realm) then how is a photon ever created AT the event horizon - they don't just pop into existence without something else happening. And the "something else happening" will affect the size of the EH and mean that the photon is now not AT the event horizon, just close.

My point though is as I have said and referenced.....a photon emitted just on the EH, directly radially away, will never be swallowed and never get away.

http://casa.colorado.edu/~ajsh/singularity.html#disappearingview

...

Hadn't realised we were on two separate threads - I might have to merge

But Hawking radiation is predicted to be emitted - and that is precisely radiation which you talk about ie photons created at EH and outwards. If Hawking radiation stayed within the confines of the BH then blackhole evaporation etc would not function, BH would only get bigger, heat death of universe would not happen...

Perhaps the HR calc's take this into account in the measure of luminosity - but I have never come across this idea of a stationary photon

Today I learned that a bottle nose dolphin's brain is 1.5 to 1.7 kg and is heavier than human's brain 1.3 to 1.5 kg.

But we all know which one is the more advanced species:

“For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much—the wheel, New York, wars and so on—whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man—for precisely the same reasons.”

Douglas Adams - The Hitchhikers Guide to the Galaxy

The only stable place for photons near black hole is the photon sphere at 3/2 of the Schwarzchild radius - but as MigL says they are not stopped; they orbit at that distance. Others not in orbit either escape or loop back in. But describing what happens to an infalling test particle is fraught with trouble - what is position of observer, which coordinate system etc; gets conceptually harder when there is no inertial frame for the infaller

Thanks for the advice. Pink wine is Rosé?

Pink wine is the wine we often drink during and after diner.

I'm doubting to make honey wine, appel cider or a grape wine like Rosé.

Do you heve a good recipe?

You're in Belgium - make beer

If you do go for wine-making or brewing make sure you follow the sterilisation / cleaning procedures very carefully; the difference in taste can be remarkable.

Sensei has some amazing videos of the cloud-chamber he made - frankly I think cloud-chamber is the best home experiment there is. A little work, not too expensive equipment, safe - and you get to see particle tracks. You can spot large energetic particles, cosmic rays, muons if you are lucky, and even decay cascades if you are the sort of person who wins the lottery

 

A black hole is contained, compressed plasma, I think, and between the inner and outer event horizons I heard could be the most violent state in the universe. That is if I remember the documentary correctly.

You don't. Plasma is a state in which particles have become ionized - ie electrons float free with the positive ions in a fluid state. Even before we reach the monumental crushing power of the gravity of a black hole we find that this state is not tenable. Neutron stars (which "crush" less than black holes ) have enough inward pressure to cause some electron and protons to merge to form neutrons - so this is the opposite of the free electrons of plasma; the pressure is so great that electrons are (to an extent) not even able to exist in the atom.

we have precious little idea of what is beyond the event horizon. GR would tell us a singularity. QCD might mention things like quark or preon-degenerate state. But in reality we need a theory which deals simultaneously with gravity and the other forces all on a particle level and at very hi energy

What you may be remembering is that black holes can generate plasma - and the plasma they can generate can be amongst the hottest stuff going. The material in accretion discs and polar jets is ridiculously energetic and almost completely ionised

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

*I know it is not a word but I like it

 

Thank you for the helpful reply, I will read the links you have posted, and see what I have missed.

 

I understand Pions and Kaons like Neutrinos are made up of quarks with opposite spin that cancels out, but still have a magnetic effect due to the spin of the quarks.

..

Neutrinos are fundamental and not made of quarks

http://www.scienceforums.net/topic/107048-can-a-black-hole-explode/