It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
Right now, the universe is not expanding faster than the speed of light (71 kps is much less than the speed of light which is 300,000 kps), but very distant objects can seem like they are from our perspective (actually, we cannot see them because the light can't reach us due to all the expanding space in between).
OK I think I found better information about the current speed of the expansion of the Universe. It is indeed under the speed of light.
Black holes, nothing escapes them, but I wonder if nothing can escape from them (it is because of their gravity?), then I wonder how gravity escapes from them in the first place, and Why?
Do black holes affect the expansion of the universe? May be black holes are slowing it down?
BUT if the speed of the Universe is indeed increasing, it exceeded the Speed of light once before, can it do it again?
At the time Hubble made his findings, quasars were not known to exist. Quasars, or quasi-stellar objects, are dim point like objects we see in space that have HUGE red shifts. According to standard theory, this means they must be on the edge of the observable universe and output extraordinary amounts of energy for them to be visible. Why are quasars so important? Because their red shift does NOT correlate to their observed luminosity (brightness). In fact, Fred Hoyle (famous astronomer) commented that had Hubble first seen the plots for quasars instead of galaxies, he never would have concluded that red shift was a function of velocity (distance).
The theory proposed here is cosmic dust induces redshift of galaxy light by quantum electrodynamics (QED). QED induced redshift finds basis in the absorption of light by small particles (Mie 1908) where the particle is far smaller than the wavelength of incident light. Indeed, most of the incident light on a particle in space is scattered with only a tiny fraction absorbed. Of the light absorbed, the conservation of energy may take one of 2 paths. The particle may increase in temperature, but this is not possible because the specific heat of small particles already very low at 2.7 K vanishes at their EM confinement frequencies. This leaves the only conservation path to be the emission of the absorbed light as EM radiation at the EM confinement frequency of the particle.
The QED frequency f of light emitted from the cosmic dust particles depends on their diameter D, by the relation f = c / 2D, where c is the speed of light. The QED wavelength of emitted light is 2D. The size distribution of dust varies throughout space, but is generally submicron. What this means is the galaxy light is not always redshift in larger particles, but sometimes blueshift as the photon is absorbed by smaller particles. The redshift light we finally see on earth is the net effect of an uncountable number of blue and redshifts with submicron dust particles having diameters D of about 0.3 to 0.5 microns.
An expanding universe based on the Hubble Law for redshift of galaxy light by the Doppler effect is unlikely. Einstein's static universe is more likely.
The idea of a static universe or "Einstein's universe" is one which demands that space is not expanding nor contracting but rather is dynamically stable. Albert Einstein once proposed such a model as his preferred cosmology by adding a cosmological constant to his equations of general relativity to counteract the dynamical effects of gravity which in a universe of matter would cause the universe to collapse. This motivation evaporated after the discovery by Edwin Hubble that the universe is not static, but expanding; in particular, Hubble discovered a relationship between redshift and distance, which forms the basis for the modern expansion paradigm. This led Einstein to declare this cosmological model, and especially the introduction of the cosmological constant, his "biggest blunder".
Even after Hubble's observations, Fritz Zwicky proposed that a static universe could still be viable if there was an alternative explanation of redshift due to a mechanism that would cause light to lose energy as it traveled through space, a concept that would come to be known as "tired light".
Galaxies are also dynamic entities, changing over time. Like with large scale structure, the broad strokes of galaxy formation follow a path of "hierarchical clustering": small structures form very early on and these merge to form larger structures as time goes on. Within this larger framework, some galaxies will develop secondary features like spiral arms or bar-like structures, some of which will be transitory and some of which will persist.
This basic picture tells us that, if we look at very distant regions of the universe (i.e., galaxies with very high redshifts), we should see mainly small, irregular galaxies. For the most part, this is what we find (with some notable exceptions, as we will cover later). Starting in 1996, the Hubble Space Telescope took a series of very deep images: the Hubble Deep Field, the Hubble Deep Field South, and the Hubble Ultra Deep Field. As one would expect, the morphology of the few nearby galaxies in these images is quite a bit different from the very high redshift galaxies.
Another important indicator of galaxy evolution comes from quasars, specifically their redshift distribution. Quasars are generally believed to be powered by supermassive black holes at the centers of galaxies accreting matter; as dust and gas falls into the black hole, it heats up tremendously and emits a huge quantity of energy across a broad spectrum. For most true quasars, the amount of energy released during this process is a few orders of magnitude larger than all of the light emitted by the rest of the galaxy. In order for this sort of behavior to occur for some length of time, galaxies need to have a large quantity of dust and free gas near their cores. The bulk of observed quasars have redshifts near z ~ 2, which suggests that there was a particular epoch during the history of the universe when the conditions were right for a large fraction of galaxies. For steady-state models of the universe, this is hard to explain. On the other hand, BBT explains this quite neatly by noting that, in their early stages of formation, galaxies have a great deal of dust and free gas and galaxy collisions were also more common, which could serve as a mechanism for triggering quasar activity. With that said, it should be noted that galaxy formation and evolution remains a very open question within BBT and not without controversy.
Thanks for your question! You are correct that the process of nuclear
fusion that occurs in the cores of stars converts some amount of the
stars' mass into photons, which have no mass. However, the statement
that photons do not interact gravitationally is not true according to
Einstein's theory of relativity. In his theory, the curvature in
spacetime that produces gravity comes from energy. This includes "rest
energy", which is another word for mass, as well as other forms of
energy like the electromagnetic energy in photons. In this picture,
stars convert some rest energy into electromagnetic energy but the total
amount of energy remains the same. Since energy drives gravitation,
there is no reason to expect the expansion of the universe to be
accelerating. However, observational evidence suggests that it IS
accelerating. This is a fascinating puzzle and for now we have assigned the name "dark energy" to describe whatever it is that is causing this
Hope that helps,
-Laura & Ira
for the "Ask an Astrophysicist" team
Where can I go to get it into an official format so that I can get it peer reviewed?