Why is our universe expanding and why is our solar system heating up?
- Thread starter slatr
- Start date
I don't really know why the universe is expanding (or at least why all the galaxies are moving away from each other). I guess it's just because the big bang had a massive amount of potential energy that was converted into kenetic via the galaxies. On approximately the same note... I read that all the planetary bodies are (generally) moving apart from each other. That's why we all experience shifts towards blue instead of red. Why is this? Why are all of the galaxies moving away from each other?
As for the heating up part of the question, I'm also unsure of this. It may be due to the "inevitable heat death of the universe", as Hawking puts it.
I believe the concept behind this is that heat energy is "chaotic" and can not be calmed down to a state of usable energy without expending an even larger amount. Due to the fact that we will always be saturating the universe with more heat energy than we're converting to other types of energy, eventually all of the energy in the universe will be converted to heat--everything will be completely chaotic-- just a big ball of energy.
As for the heating up part of the question, I'm also unsure of this. It may be due to the "inevitable heat death of the universe", as Hawking puts it.
I believe the concept behind this is that heat energy is "chaotic" and can not be calmed down to a state of usable energy without expending an even larger amount. Due to the fact that we will always be saturating the universe with more heat energy than we're converting to other types of energy, eventually all of the energy in the universe will be converted to heat--everything will be completely chaotic-- just a big ball of energy.
Apparently, the universe is expanding because of the effects of the big bang, or, at least thats what we still currently believe.
In other words, that explosion that created the universe still has everything moving apart today.
As far as the heat question, some basic chemistry can answer that.
A reaction is usually more spontaneous (happen naturally) if the change in energy is negative.
So, energy usually has to be released for a reaction to take place, get it? Standardly, the only way to forgo this
is to input energy into a reaction.
In other words, that explosion that created the universe still has everything moving apart today.
As far as the heat question, some basic chemistry can answer that.
A reaction is usually more spontaneous (happen naturally) if the change in energy is negative.
So, energy usually has to be released for a reaction to take place, get it? Standardly, the only way to forgo this
is to input energy into a reaction.
Expanding _and_ heating up?
Nope. The universe has been expanding ever since the big bang, but it is also cooling down. Search the net for a timeline of the big bang. The numbers representing the conditions (temperature, times) of the universe during the BB will astound you.
Nope. The universe has been expanding ever since the big bang, but it is also cooling down. Search the net for a timeline of the big bang. The numbers representing the conditions (temperature, times) of the universe during the BB will astound you.
Indeed, Universe is expanding and cooling(hence the microwave background being microwave, not gamma). Also, you can't think of the big bang as an explosion in space. Its more of an explosion of space. The galaxies are not in general moving away from each other, rather the space in between them is expanding. Things like our solar system, galaxies, galaxy clusters do not expand this way since they are gravitationally bound.
Perhaps the OP was refering to the so called "heat death" which is the destiny of our universe.
Since all reactions will result in the generation of some heat (=thermal radiation) the universe will eventually consist ONLY of heat: All the matter and other forms of energy will have been transformed into heat.
However, this still does not mean that the universe is "heating up" since it is also expanding.
Since all reactions will result in the generation of some heat (=thermal radiation) the universe will eventually consist ONLY of heat: All the matter and other forms of energy will have been transformed into heat.
However, this still does not mean that the universe is "heating up" since it is also expanding.
The universe is expanding due to dark energy. If it were because of a big bang then it would be decelerating, instead expansion is accelerating.
Let's try not to post theories as facts, mkay? At least point out that 'Some scientists believe......'
While there is compelling evidence for dark matter, the evidence for dark eneregy isn't nearly as strong. A number of competing theories explain the expansion acceleration just as well as dark energy.
The simplest theory is that the universe expansion is gravitationally bound. Gravity, which has been shown to travel at the speed of light is inversly affected by distance (as is light). Once the universe expanded past a certain threshold the overall effect of gravity on every other body in the universe weakened enough to no longer slow the expansion. Once you reach this point the expansion is a continuing chain reaction, the universe expands, gravity has less effect on bodies farther away, the accleration continues...
Bill
I answered the expansion question in another post.
The 'heating up' is just a natural biproduct of a star whose output changes over time. The solar output cyclic (and the cycles are large, not a couple of years, or even a couple hundred years). You think it's hot now, wait until Sol becomes a red giant
He's asking two diffrent questions which you've lumped together. Question one, why is the universe expanding (lots a news article on this lately) and quesiton two, whyis the solar system (NOT the universe) apparently heating up (lots of news articles on this lately as well). They aren't related events, but most responders are answering the question as if he asked 'why is the universe expanding and heating'.
MrDudeMan
Lifer
- Jan 15, 2001
- 15,069
- 94
- 91
Ah, I see now. Thanks. Also thanks for your post earlier. So basically the momentum of all the "big mass" (galaxies) is no longer slowed down by gravity because of how far it is from other mass (galaxies)? I am assuming this theory assumes the initial velocity of all galaxies was sufficient to overcome gravitational effects.
Remember there is a difference between 'The galaxies have velocity' and 'The space between them is expanding'. Astronomers make a difference between cosmological redshifts and dopler redshifts. Dopler corresponds to movement to or away from us, while cosmological redshift is due to the expanding universe. The biggest evidence that this view is correct, is the CMBR (cosmic microwave background radiation). The CMBR is light which was omnipresent in the early universe, as the universe expanded and cooled it became transparent to light ~300 000 years ATBB. Once this happened the light was free to travel anywhere it pleased and as the universe expanded further the light was cosmologically red shifted. The initial light was ridiculously energetic and it is now in the microwave range--a very big redshift.
In an expanding universe the individual galaxies have no momentum corresponding to their recessional velocities(an unfortunate terminology). The problem stated above is akin to the horizon problem in cosmology, its also solved by inflation I believe.
As for Dark Energy, there is fairly substantial evidence for it although who knows it is by definition undetectable as of yet. The short of the story behind it is that the universe is indeed accelerating in its expansion due to a non-zero vacuum energy.
In an expanding universe the individual galaxies have no momentum corresponding to their recessional velocities(an unfortunate terminology). The problem stated above is akin to the horizon problem in cosmology, its also solved by inflation I believe.
As for Dark Energy, there is fairly substantial evidence for it although who knows it is by definition undetectable as of yet. The short of the story behind it is that the universe is indeed accelerating in its expansion due to a non-zero vacuum energy.
This article explains it better than my brief description. That said, I'm not saying that this theory is correct, only that it's as much of a theory as saying dark energy is the cause (we really don't yet have evidence for dark energy, while we do have evidence for dark matter)
Bill
I'm not current on theories of Dark matter/energy, but I've always had an interest in the field. My understanding is that dark matter/energy is the theory behind why galaxies have the structure they do, as the amount of visible mass doesn't account for their structure/behaviour.
Randomly thinking about it, i wondered to myself if radiated energy would account for it. Energy and matter are different forms of the same thing. Galaxies have to contain a lot of energy that is just zooming off in all directions from various points of origin. Each star is radiating a massive amount of energy, and it basically saturates the empty space. (pick any point in the galaxy, and every star you can see from there is contributing energy to that particular spot.) That's a lot of energy if there's a billion suns contributing to the energy in a particular spot, even if only weakly.
Anyone with more knowledge than i care to comment/shoot down this idea of mine?
Randomly thinking about it, i wondered to myself if radiated energy would account for it. Energy and matter are different forms of the same thing. Galaxies have to contain a lot of energy that is just zooming off in all directions from various points of origin. Each star is radiating a massive amount of energy, and it basically saturates the empty space. (pick any point in the galaxy, and every star you can see from there is contributing energy to that particular spot.) That's a lot of energy if there's a billion suns contributing to the energy in a particular spot, even if only weakly.
Anyone with more knowledge than i care to comment/shoot down this idea of mine?
OMG the solar system is heating up. We must stop pumping out greenhouse gases. evil evil earthlings.
silverpig
Lifer
- Jul 29, 2001
- 27,703
- 12
- 81
Roger Penrose gave a talk at my university a few months back. He suggested that once the universe evolves to a point of existing only as photons time and hence distance have no meaning. One can then renormalize the universe to being a singularity and you get a big bang
silverpig
Lifer
- Jul 29, 2001
- 27,703
- 12
- 81
The WMAP data strongly supports the dynamics of the universe as being driven by dark energy. It's not just a guess.
And the idea is that it is dark energy which drives the expansion. No dark energy = no continued acceleration. You say that as gravity becomes weaker the acceleration continues. You need a force to drive the acceleration. If you just shut off gravity and had no dark energy there would be no acceleration.
That could be an incorrect presumption. If you 'shut of gravity' and consider that space is 'expanding' then the areas that have expanded expand again (and so on). This to an observer appears as acceleration.
See the link I posted earlier...
Bill
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