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Name: James
Status: student
Grade: 9-12
Location: MD
Country: USA
Date: Spring 2012


Question:
A sun has mass. This mass causes it to collapse on itself, forming heavier and heavier elements. Eventually the sun will collapse and cause a black hole to form. The Earth also has a mass and gravity also tries to make the Earth collapse like the sun. The Earth however does not collapse like the sun. This occurs because of the quantum mechanical phenomenon known as Pauli's exclusion principle. The Pauli exclusion principle says that two electrons with the same spin state cannot occupy the same quantum orbital state. This prevents the earth from collapsing on itself. A photon has energy using Plank's E=hf equation. Using Einstein's E=mc^2 equation a photon has a relative mass. This relative mass will produce a force known as gravity. This force is explained through Einstein's Theory of General Relativity. Now why does a photon not collapse like the earth? Is there a principle similar to Pauli's exclusion principle that keeps a photon from collapsing? My question is what force combats the gravity of a photon, so that the photon does not collapse on itself and from a black hole like the sun.

Replies:
James,

A lot of deep thinking here, but there are too many wrong connections made upon which your ultimate conclusions are based on.

Earth will not collapse in on itself to become a black hole because it is not a star. That process of star decay is a result of nuclear reactions. The ultimate outcome of whether a star becomes a black hole or a white dwarf depends on its size. Earth does not have ongoing nuclear reactions like Sun and will not decay like a star.

Our Sun will not decay to a black hole, instead it will morph into a White Dwarf. Please refer to this online article:

http://en.wikipedia.org/wiki/Sun#Characteristics

In the “Lifecycle” section of this Wikipedia article, we find this description of the future of our Sun:

The Sun does not have enough mass to explode as a supernova. Instead, in about 5 billion years, it will enter a red giant phase. Its outer layers will expand as the hydrogen fuel at the core is consumed and the core will contract and heat up. Hydrogen fusion will continue along a shell surrounding a helium core, which will steadily expand as more helium is produced. Once the core temperature reaches around 100 million kelvins, helium fusion at the core will begin producing carbon, and the Sun will enter the asymptotic giant branch phase. Following the red giant phase, intense thermal pulsations will cause the Sun to throw off its outer layers, forming a planetary nebula. The only object that will remain after the outer layers are ejected is the extremely hot stellar core, which will slowly cool an

Photons are massless. Interactions between subatomic particles can be described in two ways, one by force fields, the other by the exchange of force carrier sub-atomic particles also known as quanta. Please see the article at this URL:

http://en.wikipedia.org/wiki/Force_carrier

Photons are the quanta for the electro-magnetic force and as far as we know has no connection to gravity.

I get these words from “50 Physics Ideas You Really Need to Know” by Joanne Baker, Quercus Publishing, 55 Baker St, 7th Floor, South Block, London, W1U 8EW, 2007, ISBN-10: 1 84724 148 4, Page 147: “One thing that is not included in the standard model (of sub-atomic particles) is gravity. The ‘graviton’, or gravity force carrying particle, has been postulated but only as an idea. Unlike light, there is no evidence yet for any graininess in gravity. Some physicists are trying to put gravity into the standard model in what would be a grand unified theory (GUT), but we are a long way off yet.”

So please back up your thoughts and be more careful of the conclusions you build your theories on.

Sincere regards, Mike Stewart


James E.,

One great difference between sun and earth is temperature. The sun is hot enough that atomic structure does not exist. The sun is a “plasma”, electrons flying around separate from the nuclei. In the sun, the very hot protons can join together into helium nuclei. These can then join into even heavier nuclei. They can get much hotter, thus making the number of quantum states is greater. This allows the particles to be closer together.

As for photons, they do not have any size to them at all. They can be right on top of each other, but they cannot stop moving. Photons can suddenly change into electron/anti-electron pairs. Photons, like all single particles, can do strange things if it is not over too great a distance or for too long a time. Protons are not single particles. They are composed of three quarks. Quarks do not have any size to them. They bounce around each other, giving the proton its volume. Also, photons and up/down quarks do not have mass. The mass of a proton comes from the energy that holds the quarks together (E=mc^2).

Dr. Ken Mellendorf Physics Instructor Illinois Central College


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