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Accelerating expansion of the universe

 
 
cheeser
 
Reply Sat 13 Oct, 2012 02:51 pm
I am just a student, so at sixth form and my physics and maths isnt at all fleshed out so dont shoot me down. But a while a go i came across the notion of a higgs field, and heard that expansion was accelerating. I had also heard that "dark energy" what ever it is, is a constant. So an idea crossed my mind, that an expanding universe would result in an expansion of this "higgs field" so, i thought that matter would interact with less of this " higgs field" and so be awarded less mass and have a weaker force of attraction. I had also heard that the strength of gravity had "weakened" so thought that it might fit with this. Finally i thought that the decreasing ratio of gravity to "dark energy" would mean faster expansion. I have no idea whether any of this is true and didnt know how to ask someone without feeling like an idiot. So if i am wrong could you tell me why and what the scientific concensus actually is. Btw this is my first post on this forum.
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Type: Question • Score: 2 • Views: 1,280 • Replies: 15
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dalehileman
 
  1  
Reply Sun 14 Oct, 2012 01:44 pm
@cheeser,
If I understood I'd respond

Where is everyone else
cheeser
 
  1  
Reply Sun 14 Oct, 2012 04:01 pm
@dalehileman,
What do you mean
dalehileman
 
  1  
Reply Mon 15 Oct, 2012 10:55 am
@cheeser,
If I understood I'd respond: If I were a cosmologist I'd answer to "what the scientific concensus actually is"

Where is everyone else: Why aren't others responding
cheeser
 
  1  
Reply Mon 15 Oct, 2012 01:03 pm
@dalehileman,
Sorry, i dunno : my first post, wasnt even sure whether i would get a response
dalehileman
 
  1  
Reply Mon 15 Oct, 2012 01:28 pm
@cheeser,
Quote:
wasnt even sure whether i would get a response
Yes, no, Che, it's pretty technical

You might consider condensing it with everyday language for the Average Clod (me)
0 Replies
 
Zarathustra
 
  1  
Reply Tue 16 Oct, 2012 04:15 pm
@cheeser,
Your thinking is ok but your facts are bit off. First, the universal gravity constant G is not changing. The reason for the accelerating expansion is not because of a weakening gravity but because of dark energy, which provides a force against gravity. Before dark energy was confirmed it could have been that expansion was increasing because of a weakening gravity force. It is now known that it is because of dark energy.

The fields in particle physics are infinite entities so there is no need for anything to “stretch”. The Higgs field exists at every point in space.

You cannot assume that if a field is “stretched” (if possible for the particular field) that this would mean a reduction in the effect of the field. In fact for fields with asymptotic freedom the more force used against the field the greater the field strength becomes – to infinity.

This is how the strong force works. While you are not stretching the field, when you attempt to separate the quarks in a nucleon, the farther you pull them apart the stronger the strong force becomes. It is not possible to completely separate them.

The concept of the Higgs field can be bit difficult to discuss as there is a good bit of information one needs to have it make much sense. For example what the Higgs field actually does is to break what is known as Yangs-Mills symmetry. The Yang-Mills field is a basic multi-component field (24 component fields). In breaking this symmetry it causes fermions to gain mass but not gluons as they are not affected by the Higgs field. As you can imagine that leaves out a LOT of detail.

It is also interesting to note that the concept that Higgs had was first seen as only providing a mathematical process that allowed deep analysis of Yang-Mills and other “gauge” symmetries. It was only later that it was determined that the concept could be used to answer one of the most fundamental questions in physics: where does mass come from?

As this is your first post I would point out the “Ask the Experts” is a marketing label not a true evaluation of the type of responses you can expect here.
roger
 
  1  
Reply Tue 16 Oct, 2012 04:20 pm
@Zarathustra,
Zarathustra wrote:

As this is your first post I would point out the “Ask the Experts” is a marketing label not a true evaluation of the type of responses you can expect here.


I think it's time to update the sig line, Zarathustra.
dalehileman
 
  1  
Reply Tue 16 Oct, 2012 05:49 pm
@Zarathustra,
Yea Zara, G was the first puzzlement as I hadn't heard that it changes either
0 Replies
 
cheeser
 
  1  
Reply Tue 16 Oct, 2012 11:56 pm
@Zarathustra,
Excellent, thank you. I now have a place to start, i was finding it difficult trawling through info on the web. Btw where should i be asking questions if not here?
Zarathustra
 
  1  
Reply Wed 17 Oct, 2012 01:15 am
@cheeser,
If this site fit your needs, fine. It is just that the site shows up on Google searches with the tag line I noted in the previous post. There are some sites that do provide answers by credentialed posters and I just didn’t want you to wait around for a cosmologist to answer your questions, here.

It can be frustratingly difficult to find information on the web, so I can sympathize with your problem.
0 Replies
 
cheeser
 
  1  
Reply Wed 17 Oct, 2012 05:36 am
@Zarathustra,
so when you say that its dark energy, does that mean that dark energy is actually increasing? it has to doesnt it?, in order to achieve an acceleration in the expansion of the universe, rather than an equilibrium with no resultant.
Zarathustra
 
  1  
Reply Wed 17 Oct, 2012 12:08 pm
@cheeser,
I would say the best answer is we don’t know yet. It has only been recently that we have obtained the first real measurements of dark energy. So astronomers are still trying to figure out “how much” dark energy there is. The source of the energy, its characteristics, and history, will come later -- perhaps.

Again, your conclusion makes sense but until we know more I don’t know if it is correct. For example, you get into your car and accelerate down the road hitting 60km/h. You come to a steep hill and your acceleration and velocity increase, was this caused by an increase in the energy expended by the engine? No. It was the hill. It could be something analogous to this in terms of dark energy. It may be a steady dark energy but some other change that is causing the increase in the rate of expansion. We currently know so little.
cheeser
 
  1  
Reply Wed 17 Oct, 2012 04:30 pm
@Zarathustra,
Hmmmm interesting. Can I ask? Are you a scientist/ have you studied physics? Or are you just someone who takes an interest?
Zarathustra
 
  1  
Reply Wed 17 Oct, 2012 08:11 pm
@cheeser,
One of my degrees is in “science”, in what used to be called physical chemistry (this is differentiated into many sub-fields today). I worked in the field directly for about 5 years. I now occasionally require this knowledge on some projects but mostly don’t use the knowledge very often anymore.

My knowledge of astronomy comes from being an amateur astronomer. It allows me to try of keep up on developments in addition to doing observations. My basic grounding in science certainly helps with the hobby.
0 Replies
 
Zarathustra
 
  1  
Reply Tue 30 Oct, 2012 05:45 pm
@roger,
Wow. I can’t tell you the thrill of having one of the A2K old guard actually use the valuable piece of real estate that is a signature line to rag on me, an A2K nobody. I haven’t been this honored since I was next to the stage at a Linda Ronstadt concert and from time to time her spit would hit me when she sang. “This is the kind of publicity, my name in print, that makes people.”

In a true and just world, sir, you would be King!
Smile
0 Replies
 
 

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