How does an expanding space time explain this?

Started by Solitary, September 16, 2015, 04:53:09 PM

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Solitary

There is nothing more frightful than ignorance in action.

Baruch

#1
Thanks for posting this.  There is always something new, and often mysterious.  The idea that the Cosmological Constant (it is a simple addition to the neutral GR equation of a simple number) explains anything, even Dark Energy ... is a stretch.  Pythagoras wouldn't have made such a simple assumption, he at least understood harmonic progression ;-)  Certainly in the early universe, there was mostly hydrogen and a small percentage of helium.  Just explaining what happens after that, is a big job, that is constantly being improved today.  Like the notion of super giant stars in the early galaxies, that became congregated into giant black holes/quasars ... and produced most of the early heavy elements ... is pretty new.  Early on, there weren't enough heavy elements to form an Earth-like planet.

We have evolved from deus ex machina ... to cosmologist ex machina.  With equations ... like good Pythagoreans.
Ha’át’íísh baa naniná?
Azee’ Å,a’ish nanídį́į́h?
Táadoo ánít’iní.
What are you doing?
Are you taking any medications?
Don't do that.

CrucifyCindy

You guys just don't get that this universe is just a corrupted simulation of another universe.
“Rational thought is a failed experiment and should be phased out.”
 William S. Burroughs

حسن اÙ,,صباح - Ù,,يس هناك Ù...ا هو صحيح ØŒ ÙƒÙ,, شيء Ù...سÙ...وح به


doorknob

Quote from: CrucifyCindy on September 17, 2015, 12:32:50 AM
You guys just don't get that this universe is just a corrupted simulation of another universe.

Are we a lexx fan?

josephpalazzo

Quote from: Baruch on September 16, 2015, 07:42:12 PM
The idea that the Cosmological Constant (it is a simple addition to the neutral GR equation of a simple number) explains anything, even Dark Energy ... is a stretch. 

A stretch?!? Not really. The cosmological constant (cc) is energy density. So it is not a stretch that it would play a role in explaining Dark Energy. Whether the cc gives the complete story is another issue as we don't know how good GR is in explaining the full story of our universe.

SGOS

It seems like I read some place that even Einstein had reservations about the addition of the cosmological constant to GR.

josephpalazzo

When Einstein published his GR (1915), the general thinking at the time was that the universe was stable and stationary. In order to fit his theory with that, he needed to have the cosmological constant (cc) to take on some value. Ten years later Hubble had discovered that the universe was expanding, so Einstein's fixing of the cc was no longer valid. However, when it was discovered in the 1990's that the universe was actually accelerating, the cc had to be revived to explain this new data.

surreptitious57

It is currently not known what either dark energy or dark matter are. The terms them selves are merely placeholders. And together
they make up ninety six per cent of the observable Universe and there is still very much left to discover. And a Theory Of Quantum
Gravity has to be discovered which will cancel the famous incompatibility between Quantum Mechanics and General Relativity. And
trying to establish what happened before the Big Bang since it is far more probable that it was simply the beginning of local cosmic
expansion as opposed to the beginning of absolutely everything. The twin discoveries of Q M and G R in the twentieth century were
the pinnacle of physics in that period. Although there is still far more to be achieved before a truly fundamental and comprehensive
understanding of observable phenomena can be established. Assuming of course that that is actually possible. Given how science is
an inductive discipline that relies upon evidence to validate its hypotheses I am sceptical of this. For it is an eternally self correcting
system. So there is never a point at which scientific knowledge is therefore absolute. For there will always be gaps in understanding
A MIND IS LIKE A PARACHUTE : IT DOES NOT WORK UNLESS IT IS OPEN

josephpalazzo

Quote from: surreptitious57 on September 19, 2015, 03:47:56 AM
Given how science is an inductive discipline that relies upon evidence to validate its hypotheses I am sceptical of this. For it is an eternally self correcting
system. So there is never a point at which scientific knowledge is therefore absolute. For there will always be gaps in understanding

You make it sound as if that was a bad thing when in reality it is a good thing that science is a method that allows self-correction, as oppose to religious belief which claims to have monopoly on truth.

Termin

 Well as space expands, anything to is connected to space itself is likely  to have it bonds stretched or even broken, obviously this video was connected to YouTube via one of these bonds, which have now been severed. :)
Termin 1:1

Evolution is probably the slowest biological process on planet earth, the only one that comes close is the understanding of it by creationists.

Unbeliever

I wonder whether the accelerating expansion of space-time might become so great that it would eventually rip virtual particles apart so fast as to keep them from ever annihilating? If so, what would be the result?

God Not Found
"There is a sucker born-again every minute." - C. Spellman

josephpalazzo

Quote from: Unbeliever on September 23, 2015, 05:26:50 PM
I wonder whether the accelerating expansion of space-time might become so great that it would eventually rip virtual particles apart so fast as to keep them from ever annihilating? If so, what would be the result?



That would be unlikely. Dark Energy, responsible for this acceleration, is far too weak. If you could gather all the energy of Dark Energy from here to I billion light-years away from our planet, you would have enough energy to light a lightbulb.

Unbeliever

OK, but the density of dark energy stays the same, while the matter/radiation density decreases. So the ratio will eventually become so great that it's small energy content "now" may not matter. I'm talking several trillion years in the future, by which time the "heat death" may have occurred.
God Not Found
"There is a sucker born-again every minute." - C. Spellman

josephpalazzo

Quote from: Unbeliever on September 23, 2015, 05:41:39 PM
OK, but the density of dark energy stays the same, while the matter/radiation density decreases. So the ratio will eventually become so great that it's small energy content "now" may not matter. I'm talking several trillion years in the future, by which time the "heat death" may have occurred.

Yes, but in a trillion years, the earth won't exist. So who is going to witness this ripping apart... oh wait, God...:lol_hitting: