Big Bang

MeteorWayne · Aug 21, 2006

When any random motion is compressed by the reduction in diameter of rotation, whatever motion there was will tend to form discs. Like it or not the explanation is self consistent. Ain't physics wonderful <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

SpeedFreek · Aug 21, 2006

Isn't this supposedly where it all neatly comes back to the CMB? It was the "clumpiness" in the CMB that helped to validate BB theory if I remember. The clumpiness is a reflection of the slight variance in distribution of matter after the big bang. Without the clumpiness, nothing would have formed out of the uniform plasma as gravity had nothing to work with. <img src="/images/icons/smile.gif" /> Once there were concentrations of mass, the process speeded up until there were spaces in between all the clumps of stuff. Then big clumps started to attract smaller clumps. When these smaller clumps happened to pass close to other clumps as they moved they would provide a sideways attractive force which in turn produces spin. And in the end, everything would be spinning. (Please excuse all the highly scientific terminology there!) It has been suggested that the clumpiness may have been induced by good old quantam fluctuations in the fabric of spacetime or some such. <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

Saiph · Aug 21, 2006

It's simple to explain where the gas got it's initial rotation, it's orbiting the center of the galaxy. There's also the torques caused by nearby stars, the pressure differentials caused by nearby supernovae or passing stars, and all sorts of things to cause disturbances in the cloud. To see how this can cause rotation, take a cup of coffee, add some cream, and then just dip your spoot straight it. This simple act induces circular swirls in the coffee, and induces all sorts of motion. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

nevyn · Aug 21, 2006

But you have to think from first principles. How did the very first galaxy form. The first gas cloud did not have a center (isn't that the definition of isotropic: there is no center?), it did not have near by stars or anything, it just had emptyness. And I can't understand this coffee example. It is you putting the spoon in causing the motion, of course touching molecules will cause others to move. But we are talking about a gas cloud. Specks of dust, particles, whatever. It is a collection of very small things with a lot of space between them. If you want the coffee example to hold some sort of meaning here, then we need to introduce God to stir the gas cloud.

Saiph · Aug 22, 2006

Just because there's lots of space between atoms, doesn't mean you don't get vortices and disturbances. Afterall, there is tons of space between atoms in the atmosphere. It's really a matter of scale. Swiping a hand through a nebulae will displace an atom or two, big deal it is not. However, a nearby star or supernovae...that will make waves and a significant event. Anyway, first principles, no nearby stars or supernovae to star thing spinning that way, it's still possible to get spin. Take a portion of the cloud in which you only have the random atomic motion, and you may end up with a slight imbalance, as you have a few atoms moving one way more than the others (due to taking a portion of the whole). This small portion begins to collapse into it's own cloud, if it's a bit denser/cooler than the surroundings...and that very minor imbalance due to random chance still translates into a net angular momentum for the region. Now, the other portion you didn't choose, was of course a few atoms short moving in the direction of the first portion. This results in a net imbalance again, but in the other direction. You now have two spinning clumps that balance eachother out to no net spin. Now, this scenario ignores the slight irregularities in temperature after the BB (as indicated by the ever so slightly spotty CMBR). This alone will allow the thermal radiation from hot spots to irregularly heat the cold spots...and cause disturbances akin to passing objects. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

derekmcd · Aug 22, 2006

The buck has been passed <img src="/images/icons/wink.gif" />. A perfect test of this conservation is to sit and spin in a desk chair with your legs sticking out, then bring them in and watch your rotation increase. The same is true with these gas clouds. Keep in mind, they can be several 100 to several 1000 (or more) light years across. Even the slightest most imperceptable motion in them will be hugely amplified as those portions collapse into more dense regions. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

SpeedFreek · Aug 22, 2006

nevyn: I was addressing first cause in my above post. If the "first" gas cloud was completely uniform, galaxies and stars would never have formed. But it was not completely uniform, as shown by the signature it has left behind in the CMB. As soon as you have any slight concentrations of gas, gravity starts working, pulling the less dense gas towards the more dense gas. You end up with clumps of gas, all different sizes, with gravity acting to pull the smaller ones towards the larger ones. Interactions between these clumps of gas will induce spin into the system. And as for the variations in the CMB being very slight. This is the end result after billions of years of cooling. Of course all the temperatures will be pretty close to absolute zero. But when it all happened the differences would have been more pronounced than this. <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

alokmohan · Jun 24, 2007

Just after big bang what was temp of universe?Then give and idea of reduction.

h2ouniverse · Jun 24, 2007

Depends on what you call "just after". Generally the threshold considered is the exit from the Heisenberg "uncertainty bubble", when quantum fluctuations cease to affect the universe as a whole but begin to affect only parts of the universe. This occurs at one Planck length, after one Planck time, and at one Planck temperature. In absolute units (or Planck units), this corresponds to a length of 1, a time of 1, and a temperature of 1. In Planck units all fondamental constants are arbitrarily set to 1. Expressed in Kelvins, Planck temperature = 1.417e32 K (141.7 millions of trillions of trillions of degrees). This is the max achievable temperature of a system beneath which separate particles can be considered. Regards.

derekmcd · Jun 24, 2007

"Just after big bang what was temp of universe? It was really hot <img src="/images/icons/smile.gif" />. Plasma was dominate. "Then give and idea of reduction. Space cooled down and matter coalesced. We see what we see today, becaused everything cooled down. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

alokmohan · Jun 24, 2007

In the beginning we had planck temperature only .Too big amount.H20 thank you very much.

weeman · Jun 25, 2007

Eh, who really cares!? The numbers that represent the temperature of the universe at the time of the big bang are so absurdly huge that we might as well call them infinity <img src="/images/icons/laugh.gif" /> Generally the threshold considered is the exit from the Heisenberg "uncertainty bubble", when quantum fluctuations cease to affect the universe as a whole but begin to affect only parts of the universe. Are these the same fluctuations that might have lead to the first stars or the first galaxies? If you say that this 'exit' from the uncertainty bubble was the point when quantum fluctuation influences became more regional (rather than universal) then woudn't this have lead to the different concentrations in mass that eventually lead to early galaxies? Sorry, that's a long question <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

alokmohan · Jun 25, 2007

Let us dwell on facts.In the beginning we had 10 to the power 32 degrees.

h2ouniverse · Jun 25, 2007

At a distance of 1 from Big Bang singularity (in spacetime), you begin to experience "local effects". But the first local effects are rather at the level of clusters of galaxies rather than stars. Whether gravitational collapse of clusters and galaxies went fast enough to concentrate matter before a more local accretion could give birth to stars is another debate... Let's see what Planck satellite gives when launched next year. Regards.

mudman · Dec 2, 2007

If theh theory is correct and the universe is expanding. Where did it originate from?

billslugg · Dec 2, 2007

mudman Welcome to Space.com! The 'where' is easy. Right under your nose. From any spot in the universe an analysis will show that spot to be the exact center. No matter where you go. As to what was there before hand, the question is disallowed because it is considered that time began with the big bang. Some cosmologists argue that the big bang began with a fluctuation in the vacuum. If you ascribe quantum numbers to the vacuum, and they constantly change, every so often all of the Liberty Bells will line up and a big bang will occur. That is about the extent of what I can relate. <div class="Discussion_UserSignature"> </div>

alokmohan · Dec 3, 2007

Space and time are not two seperate things.There is no space,time.There is spacetime only.So what was before big bang ,the question dees not arise.

docm · Dec 3, 2007

And even when a 'big bang' occurs it's more of a 'big fizz' in that energy appears randomly then condenses into a froth of particles. <div class="Discussion_UserSignature"> </div>

themage · Dec 3, 2007

If you want to let your imagination loose, might I suggest looking into M-Theory. It describes the universe before the big bang. In very simple terms, the universe sits on top of a membrane that is parallel with other universal membranes. And one "day" 2 membranes collided and we had the big bang. http://en.wikipedia.org/wiki/M-theory#Big_Bang_Theory

space_coops · Dec 4, 2007

Yes, the big bang and Universe that followed, was an "explosion" of spacetime. Thus, nothing could have been before then.

weeman · Dec 8, 2007

Yes, the big bang and Universe that followed, was an "explosion" of spacetime. Thus, nothing could have been before then. I've never liked the term 'nothing' to be used in relation to pre-big bang. We have no idea what happened before the inflation, saying there was nothing is stating that we know what happened before the big bang (or should I say, what didn't happen <img src="/images/icons/wink.gif" /> ) Of course, even 'nothingness' is a theory, like everything else. The big bang could have just been an inflation of THIS universe, not the ONLY universe. I firmly believe that our universe is indeed finite in age. The way I see it, the universe wouldn't exist as we see it today if infinities are brought into consideration. The very fact that stars, planets, and life on Earth exists, should be solid evidence that nothing in the universe can be represented with infinities. Take this line for instance: [---------------------------------------------] Lets say this line represents infinity. Now, this line does have a beginning and an end, but just for the sake of this argument, lets say the line is infinity. What do you come up with if you cut the line in half? Infinity. And what do you come up with if you cut it in half again? Infinity. No matter how many times you slice the line, the new line that you come up with will always represent infinity. So, the fact that Earth exists, must be proof that the universe is not infinite in age, meaning it has an absolute point in time at which it began. If infinity time existed before Earth, then Earth should not be here, because it would have taken an infinite amount of time for Earth to form, meaning it never happens in the first place. <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

siarad · Dec 8, 2007

Ah but infinity is not something it's immeasurable

brellis · Dec 23, 2007

I still wonder why the big bang occurred. If you ascribe quantum numbers to the vacuum, and they constantly change, every so often all of the Liberty Bells will line up and a big bang will occur. From this tidy statement, I get that the big bang wasn't inevitable. Rather, it was the consequence of a random fluctuation in the pre-universe vacuum. It would seem that some universes start loudly, whereas others are the more silent but deadly type. <img src="/images/icons/wink.gif" /> I'm reading "Origins" by Neil de Grasse Tyson, and I still can't get my brain around some of the quantum stuff and dark energy/matter. <img src="/images/icons/crazy.gif" /> <div class="Discussion_UserSignature"> I'm a recovering optimist - things could be better. </div>

weeman · Dec 24, 2007

I still wonder why the big bang occurred. Don't we all <img src="/images/icons/wink.gif" /> From this tidy statement, I get that the big bang wasn't inevitable. Rather, it was the consequence of a random fluctuation in the pre-universe vacuum. So then could this suggest that multiple universes really do exist? If a fluctuation happened in a way that sparked our universe, then the quantum jitters must have been always happening. Would this mean that within the pre-universe vacuum new universes are being created all the time? I guess it might depend on how the fluctuations actually create a universe. Whether or not a universe being created is incredibly rare or incredibly common. Of course then we can get into the debate of how long this 'pre-universe vacuum' actually existed before our universe was created. Is it infinite? Or did it too have a beginning like our universe? These are just a few more ideas to wrap your brain around <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

alokmohan · Dec 25, 2007

Why not quasisteady state universe?The Quasiâ€“Steady State Cosmology: A Problem of Stability Shyamal K. Banerjee and Jayant V. Narlikar Interâ€University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind Puneâ€411007, India Received 1997 February 19; accepted 1997 April 18 Subject headings: cosmology: theory ABSTRACTThis paper examines the gravitational stability against small perturbations of the quasiâ€“steady state cosmological model. This model was first introduced by Hoyle et al., who in subsequent papers looked at its various theoretical and observational implications. Here we carry out a perturbation analysis of the exact solutionhttp://www.journals.uchicago.edu/doi/abs/10.1086/304606

Big Bang

MeteorWayne

Guest

SpeedFreek

Guest

Saiph

Guest

nevyn

Guest

Saiph

Guest

derekmcd

Guest

SpeedFreek

Guest

alokmohan

Guest

h2ouniverse

Guest

derekmcd

Guest

alokmohan

Guest

weeman

Guest

alokmohan

Guest

h2ouniverse

Guest

mudman

Guest

billslugg

Guest

alokmohan

Guest

docm

Guest

themage

Guest

space_coops

Guest

weeman

Guest

siarad

Guest

brellis

Guest

weeman

Guest

alokmohan

Guest

Similar threads

TRENDING THREADS

Latest posts

Share this page