How much energy is there in the Universe?

In summary: If the universe's expansion is accelerating then eventually even black holes will evaporate via Hawking radiation. The universe will become very dark and empty and cold. If there is no technology to utilize this energy then it will simply disappear. In summary, the total amount of energy in the universe is believed to be 0, which also means the total amount of mass is 0. This is because for every positive mass/energy, there must be an equal and opposite negative mass/energy. While this concept may seem strange and not fully understood, it is supported by evidence such as the flatness of the universe and the spontaneous creation of the universe without violating conservation of energy. Additionally, the expansion of the universe causes radiation to lose energy, further
  • #1
Alutoe
5
0
How much energy is there in the universe?

I've heard a lot of people saying the total amount of energy in the universe is 0, if this is the case the total amount of mass in the universe is 0. In this scenario there is an equal and opposite amount of mass/energy in the universe. How would the "negative" mass/energy act? It would need to be something when brought in contact with "positive" mass/energy would exactly annihilate each other and bring the system back to a state of 0 (with no "positive" or "negative" fluctuations). Do we see anything of this nature? Upon first look it seems like a weird concept both required and disallowed by the laws of physics, but I have the sense that I'm just not look at it from the right perspective yet.

Thanks for your help!
 
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  • #2
Alutoe said:
How much energy is there in the universe?

I've heard a lot of people saying the total amount of energy in the universe is 0, if this is the case the total amount of mass in the universe is 0. In this scenario there is an equal and opposite amount of mass/energy in the universe. How would the "negative" mass/energy act? It would need to be something when brought in contact with "positive" mass/energy would exactly annihilate each other and bring the system back to a state of 0 (with no "positive" or "negative" fluctuations). Do we see anything of this nature? Upon first look it seems like a weird concept both required and disallowed by the laws of physics, but I have the sense that I'm just not look at it from the right perspective yet.

Thanks for your help!

I don't understand it, but the basic idea is that gravity is negative.
 
  • #3
To take into account ALL of the universe we need to use General Relativity and it's math to describe it. Unfortunately there is no specific definition of energy that is fully accepted in General Relativity, so it makes it difficult to answer you. On top of that, different ways of "setting up the problem" changes things also. I know there is one "solution" if you will that says that the total energy of the universe is 0, however this is only one possible solution.

I can't explain it very well, but I know we have a thread or two here on PF about it. Try using the search function to find it.
 
  • #5
Another bit of evidence is that the universe exists at all. Only a zero energy universe can spontaneously pop into existence without violating conservation of energy.
 
  • #6
mrspeedybob said:
Another bit of evidence is that the universe exists at all. Only a zero energy universe can spontaneously pop into existence without violating conservation of energy.

Doesn't the universe ignore the conservation of energy as a whole? Take a look at the CMB. It's losing energy as time passes without that energy showing up somewhere else.
 
  • #7
Drakkith said:
Doesn't the universe ignore the conservation of energy as a whole? Take a look at the CMB. It's losing energy as time passes without that energy showing up somewhere else.

I think it's losing positive and negative energy at the same rate. Otherwise the universe would not remain flat.
 
  • #8
DrZoidberg said:
I think it's losing positive and negative energy at the same rate. Otherwise the universe would not remain flat.

How is it losing negative energy?
 
  • #9
A gravitational field is a form of negative energy. Imagine you had a single planet somewhere alone in space. Far away from any galaxies. Now on this planet you have a matter to energy converter that consumes matter and releases photons. These photons are then send into space in form if a laser beam. Far away from that planet there is a photon to matter converter that receives the laser beam and turns it back to matter. As the photons move away from the planet their wavelength increases due to gravity which means they lose energy. As a result the amount of matter created by the photon to matter converter is smaller than the matter lost by the planet. Positive energy is being lost. Seemingly vanished into nowhere. But at the same time the gravitational field around the planet has decreased, so an equal amount of negative energy was lost as well.
 
  • #10
I understand your example, but consider that expansion causes even further energy loss of radiation as time passes. If your photon-matter converter was far enough away so that expansion caused it to recede from your planet then it would produce less and less matter over time as the photon energy falls. This energy is simply gone.
 

FAQ: How much energy is there in the Universe?

How do scientists measure the energy in the Universe?

Scientists use various methods to estimate the total energy in the Universe. One common method is to measure the energy density, or the amount of energy per unit volume, in different regions of the Universe. Another method is to observe the movement of galaxies and calculate their kinetic energy. Additionally, scientists also take into account the energy stored in cosmic radiation and dark energy when estimating the total energy in the Universe.

Is the energy in the Universe constant or does it change over time?

The energy in the Universe is not constant and it is constantly changing. This is due to the expansion of the Universe, which causes energy to become more spread out over time. Moreover, the formation and destruction of matter and energy through various processes such as nuclear fusion and black hole emissions also contribute to the changing energy levels in the Universe.

How much energy is there in the observable Universe?

The observable Universe, which is the part of the Universe that we can see, is estimated to have a total energy of around 1 x 10^69 joules. This is an incredibly large amount of energy, equivalent to the energy released by trillions of supernovae explosions.

Can we harness the energy in the Universe?

While we cannot harness the energy in the entire Universe, we can harness some of the energy in the form of solar, wind, and hydroelectric power. These renewable energy sources use the energy from the Sun, which is just a small fraction of the total energy in the Universe. Additionally, scientists are also researching ways to harness the energy from black holes, which could potentially provide a nearly limitless source of energy.

How does the amount of energy in the Universe compare to other astronomical objects?

The total energy in the Universe is vastly greater than any other astronomical object. For example, the energy in our own Milky Way galaxy is estimated to be around 1 x 10^59 joules, which is much smaller than the estimated energy of the observable Universe. Even the largest known black hole, which has a mass equivalent to 21 billion suns, has a relatively small amount of energy compared to the energy in the Universe.

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