The Cosmological constant.

A few weeks ago I was watching a documentary(I have embedded the clip) and at the end it mentioned the Cosmological constant. Now to be honest I had never heard of this before and still now my understanding of it is sketchy to say the least. I was hoping some of the Science boff's could maybe explain it in a better way than I will attempt to do.

Basically the Universe is moving at a constant rate. This rate is so finally tuned that if it were to alter to even less of one % our whole universe would be different. In fact the constant is so finely tuned that even cosmologists are uncomfortable with the conclusions they have drawn.




It seems like the videos I posted have been cut short to fit in with a religious agenda. If you want to watch the whole documentary

the cosmological constant is not the growth speed of the universe (speeding up)

it is the speed light travels
if you turn a flashlight on while travelling at SOL the light from flashlight is going double?
WRONG it travels same speed even then
in fact it may slow down flashlight to make it easier to attain this constant

jus so u know

reply to post by woodwardjnr


Fine tuning arguments disturb people.

For what ever reason some things in science bother scientist, almost like it makes them question their faith in their own world view or something...

reply to post by Insearchofthetruth1987


Ummm. No.

Think of the cosmological constant as negative pressure in relation to gravity. We now know the universe is expanding, and at an accelerating rate. This could be do to a positive cosmological constant. Some might know it better as "dark energy". Without it, gravity would make everything contract, but that isn't the case, everything is moving away.

It, quite literally, has nothing to do with the speed of light.

In physical cosmology, the cosmological constant (usually denoted by the Greek capital letter lambda: Λ) was proposed by Albert Einstein as a modification of his original theory of general relativity to achieve a stationary universe. Einstein abandoned the concept after the observation of the Hubble redshift indicated that the universe might not be stationary, as he had based his theory on the idea that the universe is unchanging.[1] However, the discovery of cosmic acceleration in 1998 has renewed interest in a cosmological constant. Contents

Einstein included the cosmological constant as a term in his field equations for general relativity because he was dissatisfied that otherwise his equations did not allow, apparently, for a static universe: gravity would cause a universe which was initially at dynamic equilibrium to contract. To counteract this possibility, Einstein added the cosmological constant.[1] However, soon after Einstein developed his static theory, observations by Edwin Hubble indicated that the universe appears to be expanding; this was consistent with a cosmological solution to the original general-relativity equations that had been found by the mathematician Friedmann. Einstein later referred to his failure to predict the expansion of the universe from theory, before it was proven by observation of the cosmological red shift, as the "biggest blunder" of his life.[3]

Source

reply to post by benrl

For what ever reason some things in science bother scientist, almost like it makes them question their faith in their own world view or something...

Quite correct. Change that tuning at all, and the universe as we know it simply wouldn't exist. It shakes their foundations because it infers a god, creator, or design. It's also beyond the scope of science.

OK, I will spend some time to read all the responses. Would be good o get a good laymans description down. I'm a layman

how can it be a cosmological "constant"???

if it is NOT constant? it was proven by hubble to infact be speeding away from itself and NOT BE constant?

the name cosmological constant is indeed from the greeks
(they assumed the universe did not move or expand at all)

like i say they were wrong....

i seen a ducomentary with michio kaku in which he speaks of the comsological constant in another way
the way i stated in my last post

that the only constant in the universe is the speed of light and how the universe will bend to make light speed "constantly the fastest"

I can't speak to the physics, I understand that the universe is expanding and accelerating and science is unable to really explain why. I am waiting for dark matter to be proven to exist, other than by inference. The idea that the perfection of the universe implies God, I like very much.

Originally posted by phishyblankwaters
reply to post by benrl

 

For what ever reason some things in science bother scientist, almost like it makes them question their faith in their own world view or something...

Quite correct. Change that tuning at all, and the universe as we know it simply wouldn't exist. It shakes their foundations because it infers a god, creator, or design. It's also beyond the scope of science.

Originally posted by Insearchofthetruth1987
how can it be a cosmological "constant"???

if it is NOT constant? it was proven by hubble to infact be speeding away from itself and NOT BE constant?

You seem to be deliberately trying to misunderstand the above posts.

1) It's a constant in that that is what kind of mathematical entity it takes when expressed in mathematics.

2) It's called the "Cosmological Constant" because that's what Einstein called it. That's it's _name_. Like "Planck's Constant", or the Permitivity Constant. There are LOADS of constants in physics beyond just 'c'.

3) Hubble proved nothing of the sort. One more time, read it slow, and TRY to understand: the cosmological constant is not the speed of the expansion of the universe, it is the mathematical representation of the force that may be causing that expansion to accelerate. The strength of gravity on earth is a constant, yet if you drop something, it moves faster and faster. That doesn't mean that gravity is changing.

The cosmological constant was an idea that Einstein shoehorned into general relativity because his equations showed that the universe must be either expanding or contracting and the prevailing thought at the time was that the universe was static. So he inserted a factor into the equations that acts like a resistive force against gravity, that would be a general property of spacetime. Hubble (the guy, not the scope) showed that the universe was, in fact, expanding, and Einstein let out a sigh of relief. He later called it his biggest professional blunder. Fast forward a few decades and it turns out that the universe isn't just expanding, it's doing it faster and faster and faster. We aren't sure why. We know _some_ things about the phenomenon (like, it's HUGE with boggling amounts of energy behind it) but not much. But one of the ways of talking about the phenomenon and trying to model it mathematically takes exactly the same form as Einstein's Cosmological Constant. So they dusted off the math, and started using it again.

Originally posted by woodwardjnr
OK, I will spend some time to read all the responses. Would be good o get a good laymans description down. I'm a layman

This came up in another thread, and I found an explanation for laymen, but like any explanation for laymen, it's not 100% accurate as it omits many details and qualifiers. With that caveat, here is some info for laymen:

Dark Energy FAQ

What might dark energy specifically be?

The leading candidate is the simplest one: “vacuum energy,” or the “cosmological constant.” Since we know that dark energy is pretty smooth and fairly persistent, the first guess is that it’s perfectly smooth and exactly persistent. That’s vacuum energy: a fixed amount of energy attached to every tiny region of space, unchanging from place to place or time to time. About one hundred-millionth of an erg per cubic centimeter, if you want to know the numbers.

Is vacuum energy really the same as the cosmological constant?

Yes. Don’t believe claims to the contrary. When Einstein first invented the idea, he didn’t think of it as “energy,” he thought of it as a modification of the way spacetime curvature interacted with energy. But it turns out to be precisely the same thing. (If someone doesn’t want to believe this, ask them how they would observationally distinguish the two.)

Doesn’t vacuum energy come from quantum fluctuations?

Not exactly. There are many different things that can contribute to the energy of empty space, and some of them are completely classical (nothing to do with quantum fluctuations). But in addition to whatever classical contribution the vacuum energy has, there are also quantum fluctuations on top of that. These fluctuations are very large, and that leads to the cosmological constant problem.

And we are even closing in on a measured value for the cosmological constant as I mentioned in this excerpt from my post in the other thread here: www.abovetopsecret.com...:

What's the Energy Density of the Vacuum?

recent measurements by the Wilkinson Microwave Anisotropy Probe and many other experiments seem to be converging on a positive cosmological constant, equal to roughly 7 × 10^-27 kilograms per cubic meter. This corresponds to a positive energy density of about 6 × 10^-10 joules per cubic meter.

If you read that entire source, it elaborates on some of the qualifiers and details that are missing from the first source, though it's still an incomplete explanation.

Originally posted by woodwardjnr
Basically the Universe is moving at a constant rate.

this is false. I hope the above explanations have clarified the subject, but feel free to ask more questions if you have any.

reply to post by Arbitrageur


hey thanks that was a great reply and thanks for putting me straight. I'm still trying to get my head around it all , but it's starting to make a bit more sense. thanks for the links and info.

Originally posted by woodwardjnr
hey thanks that was a great reply and thanks for putting me straight. I'm still trying to get my head around it all , but it's starting to make a bit more sense. thanks for the links and info.

You're welcome.

To get your head around the concept, just remember Einstein was concerned that gravity would pull everything in the universe together, and he could see that had not yet happened, so, he postulated something he thought would prevent that from happening...the cosmological constant. It's not precisely anti-gravity, but can create a force which is capable of acting opposite gravity by pushing things apart instead of pulling them together. So that's one layman's way of looking at it.

Einstein later abandoned the idea and called it his biggest blunder after it became apparent the universe was expanding, in which case the expansion itself was enough to explain why gravity hadn't pulled things back together. Under this view, most scientists expected to find that the expansion of the universe was slowing down, and under certain conditions it might stop expanding and eventually collapse.

It wasn't until 1998 that observations proved the widely held view of nearly all scientists that expansion was probably slowing down was wrong, but instead the expansion was speeding up. In order to account for this, the long-dead cosmological constant was resurrected as a possible means to explain this. It's one of the most fascinating stories in modern science to me, so it is certainly worth further study if you are interested in it.

The interesting footnote is that even what Einstein called his "biggest blunder" (the cosmological constant) may turn out to be right.