Expanding Universe or, Shrinking matter?

[EddieG]

A problem with this is a photon a Quantum Mechanical object is being thought of in a classical way (i.e. having a size or width). It does not in this conventional way. So if you allow the resultant to be instead an Expectation value (i.e. instead a probability of hitting your lens), then you will get results. Because of QM you might find that you camera could in theory get a lot more than one photon assuming you at least gave it some aperture (width of lens). Say the aperture in this camera is a Micron (10E-6 m).

 

maddog

I was trying to compare a photon to a pixel, or smallest measurable unit of light.

[CraigD]

Here is a thought experiment: If you focused a camera with a lense the size of a single photon at a very distant galaxy that is bright enough for its light to reach the camera, would it only be able to take a picture of a single photon from that galaxy?

I think what you’re describing is a light detecting device – for example, a photoelectric detector or a photosensitive chemical film or plate – so small, or blocked from incoming light by a barrier with such a small opening, that for a practical exposure time, likely no more or less than one photon from a light source in a distant galaxy would be detected by it.

 

If I’ve understood correctly, then whether the answer to the question is yes or not depends on what is meant by “picture”.

 

Practically speaking, single photon detectors must be made of more exotic stuff than room-temperature camera parts that could be scrounged from a typical cellphone, devices like SPADs and ICCDs, but are commonplace in astronomy, so Eddies thought experiment can be done in more than just thought. A single photon, from a distant galaxy or a more nearby light source, can be detected. So, if “picture” is taken to mean “detected”, the answer is yes.

 

However, when I think of a picture, I think of something that has enough information I can tell what it’s a picture of. A record of the detection of a single photon usually isn’t enough to tell what source produced the photon. So while a single photon detector could detect a photon from a distant galaxy, there might be no way to tell if was from that galaxy. Rather, you’d need a lot of photons from the galaxy, focused into an image showing the galaxies shape, or diffracted into a recognizable spectrographic photo, to know that most of the photons came from a particular distant star, galaxy, or some other source with known shape or spectral characteristics. If picture is taken to have this meaning, the answer is no.

 

In principle, a long, thin tube of an opaque material, aim precisely at a distant galaxy, with a single photon detector at its end, could detect a single photon that we were fairly confident came from a source in that galaxy. Practically speaking, however, physical optical elements like this shake too much to be pointed precisely enough for this scheme to work.

 

In short, we can detect single photons, but unless the conditions in which we detect it are very precisely controlled – say a shielded box containing a sample of material we expect to emit a photon of a specific energy, spontaneously or due to an interaction with a particle we’re interested in, such a neutrino – detecting a single photon isn’t very useful.

[CarlNGraham]

Sorry for using the term 'proven'. I should have said 'indicated'.

 

 

 

The weak and electromagnetic fundamental forces seem very different in the present relatively low temperature universe. But when the universe was much hotter so that the equilibrium thermal energy was on the order of 100 GeV, these forces have appeared to be essentially identical - part of the same unified "electroweak" force. It has been inferred from high energy experiments that the unification of the strong, weak, and electromagnetic forces occurred at energies above 1014 GeV. If the ordinary concept of thermal energy applied at such times, it would require a temperature of 1027 K for the average particle energy to be 1014 GeV. Early formulation of the theories estimated that the Higgs boson would have mass energy in excess of 1 TeV, making the energies for discovery almost unattainable on the earth. Now, since the discovery of the top quark, there is tantalizing evidence that the Higgs boson may have energies in the range of a few hundred GeV and therefore within the range of present day accelerators. At Fermilab, data from the D0 detector facility is used with the masses of the W and the T quark to estimate the mass of the Higgs boson. Suggestions that it may have a mass below 200 GeV have made it one of the high priorities for high energy physics. The following link has all the information about evidence for expansion, the timeline, and the required energy levels to achieve the model. hyperphysics.phy-astr.gsu.edu/hbase/forces/unify.html - See also Steven Weinberg in "The First Three Minutes".

 

 

The interesting problem with these types of arguments is all experiments are done using instruments made of atoms.

However, the idea is that possibly atoms are shrinking.

 

If the experiment had been done billions of years ago at z = 4, maybe atoms and the instruments made from them were 5 times bigger.

Possibly made of atoms emitting/absorbing photons of five times longer wavelength at one-fifth the rate.

What would 200 GeV look like to an instrument made of those atoms?

 

The other fun question is: Is there a difference between matter shrinking and the universe expanding?

 

If you think about conservation of energy and momentum, then there is as difference as this relies on measuring velocity and therefore distance.

Is the natural reference frame of the universe based on the size of atoms, or the distance between galaxies?

[Village Idiot]

 

The universe's expansion is actually ACCELERATING! And it is dark energy that causes this acceleration.

:unsure:

 

It seems strange that we are given to accept that expansion of the entire universe is accelerating simply due to observations that certain visible objects accelerate away from us. Certain unseen matter might well be decelerating or even converging at the same time. It might all be a confusion factor caused by exchange of position between one form of matter and another.

 

If my alternative view on the cosmic acceleration story seems far out, it surely falls short of the clarification that dark energy is the underlying cause for such a mystery. :P