Hubble Interacting Galaxy NGC 6050

NGC 6050/IC 1179 (Arp 272) is a remarkable collision between two spiral galaxies, NGC 6050 and IC 1179, and is part of the Hercules Galaxy Cluster, located in the constellation of Hercules. The galaxy cluster is part of the Great Wall of clusters and superclusters, the largest known structure in the universe. The two spiral galaxies are linked by their swirling arms. Arp 272 is located some 450 million light-years away from Earth and is the number 272 in Arp's Atlas of Peculiar Galaxies.

NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and K. Noll (STScI)

Inflation Theory

The Inflation Theory proposes a period of extremely rapid (exponential) expansion of the universe during its first few moments. It was developed around 1980 to explain several puzzles with the standard Big Bang theory, in which the universe expands relatively gradually throughout its history.

Limitations of the Big Bang Theory

While the Big Bang theory successfully explains the "blackbody spectrum" of the cosmic microwave background radiation and the origin of the light elements, it has three significant problems:

• The Flatness Problem:
  WMAP has determined the geometry of the universe to be nearly flat. However, under Big Bang cosmology, curvature grows with time. A universe as flat as we see it today would require an extreme fine-tuning of conditions in the past, which would be an unbelievable coincidence.
  
• The Horizon Problem:
  Distant regions of space in opposite directions of the sky are so far apart that, assuming standard Big Bang expansion, they could never have been in causal contact with each other. This is because the light travel time between them exceeds the age of the universe. Yet the uniformity of the cosmic microwave background temperature tells us that these regions must have been in contact with each other in the past.
  
• The Monopole Problem:
  Big Bang cosmology predicts that a very large number of heavy, stable "magnetic monopoles" should have been produced in the early universe. However, magnetic monopoles have never been observed, so if they exist at all, they are much more rare than the Big Bang theory predicts.
  

The Inflation Theory

The Inflation Theory, developed by Alan Guth, Andrei Linde, Paul Steinhardt, and Andy Albrecht, offers solutions to these problems and several other open questions in cosmology. It proposes a period of extremely rapid (exponential) expansion of the universe prior to the more gradual Big Bang expansion, during which time the energy density of the universe was dominated by a cosmological constant-type of vacuum energy that later decayed to produce the matter and radiation that fill the universe today.

Inflation was both rapid, and strong. It increased the linear size of the universe by more than 60 "e-folds", or a factor of ~10^26 in only a small fraction of a second! Inflation is now considered an extension of the Big Bang theory since it explains the above puzzles so well, while retaining the basic paradigm of a homogeneous expanding universe. Moreover, Inflation Theory links important ideas in modern physics, such as symmetry breaking and phase transitions, to cosmology.

How Does Inflation Solve these Problems?

• The Flatness Problem:
  Imagine living on the surface of a soccer ball (a 2-dimensional world). It might be obvious to you that this surface was curved and that you were living in a closed universe. However, if that ball expanded to the size of the Earth, it would appear flat to you, even though it is still a sphere on larger scales. Now imagine increasing the size of that ball to astronomical scales. To you, it would appear to be flat as far as you could see, even though it might have been very curved to start with. Inflation stretches any initial curvature of the 3-dimensional universe to near flatness.
  
• The Horizon Problem:
  Since Inflation supposes a burst of exponential expansion in the early universe, it follows that distant regions were actually much closer together prior to Inflation than they would have been with only standard Big Bang expansion. Thus, such regions could have been in causal contact prior to Inflation and could have attained a uniform temperature.
• The Monopole Problem:
  Inflation allows for magnetic monopoles to exist as long as they were produced prior to the period of inflation. During inflation, the density of monopoles drops exponentially, so their abundance drops to undetectable levels.
  

As a bonus, Inflation also explains the origin of structure in the universe. Prior to inflation, the portion of the universe we can observe today was microscopic, and quantum fluctuation in the density of matter on these microscopic scales expanded to astronomical scales during Inflation. Over the next several hundred million years, the higher density regions condensed into stars, galaxies, and clusters of galaxies.

http://map.gsfc.nasa.gov/universe/bb_cosmo_infl.html
Further Reading:

• Alan H. Guth & Paul J.Steinhardt, "The Inflationary Universe", Scientific American, May 1984.
• Andrei Linde
, "The Self-Reproducing Inflationary Universe", Scientific American, November 1994.Scott Watson, "An Exposition on Inflationary Cosmology", WWWarticle, 2000.Alan H. Guth, "The Inflationary Universe : The Quest for a New Theory of Cosmic Origins

Guardian Angels

That every individual soul has a guardian angel has never been defined by the Church, and is, consequently, not an article of faith; but it is the "mind of the Church", as St. Jerome expressed it: "how great the dignity of the soul, since each one has from his birth an angel commissioned to guard it." (Comm. in Matt., xviii, lib. II).

This belief in guardian angels can be traced throughout all antiquity; pagans, like Menander and Plutarch (cf. Eusebius, "Praep. Evang.", xii), and Neo-Platonists, like Plotinus, held it. It was also the belief of the Babylonians and Assyrians, as their monuments testify, for a figure of a guardian angel now in the British Museum once decorated an Assyrian palace, and might well serve for a modern representation; while Nabopolassar, father of Nebuchadnezzar the Great, says: "He (Marduk) sent a tutelary deity (cherub) of grace to go at my side; in everything that I did, he made my work to succeed."

In the Bible this doctrine is clearly discernible and its development is well marked. In Genesis 28-29, angels not only act as the executors of God's wrath against the cities of the plain, but they deliver Lot from danger; in Exodus 12-13, an angel is the appointed leader of the host of Israel, and in 32:34, God says to Moses: "my angel shall go before thee." At a much later period we have the story of Tobias, which might serve for a commentary on the words of Psalm 90:11: "For he hath given his angels charge over thee; to keep thee in all thy ways." (Cf. Psalm 33:8 and 34:5) Lastly, in Daniel 10 angels are entrusted with the care of particular districts; one is called "prince of the kingdom of the Persians", and Michael is termed "one of the chief princes"; cf. Deuteronomy 32:8 (Septuagint); and Ecclesiasticus 17:17 (Septuagint).

This sums up the Old Testament doctrine on the point; it is clear that the Old Testament conceived of God's angels as His ministers who carried out his behests, and who were at times given special commissions, regarding men and mundane affairs. There is no special teaching; the doctrine is rather taken for granted than expressly laid down; cf. 2 Maccabees 3:25; 10:29; 11:6; 15:23.

But in the New Testament the doctrine is stated with greater precision. Angels are everywhere the intermediaries between God and man; and Christ set a seal upon the Old Testament teaching: "See that you despise not one of these little ones: for I say to you, that their angels in heaven always see the face of my Father who is in heaven." (Matthew 18:10). A twofold aspect of the doctrine is here put before us: even little children have guardian angels, and these same angels lose not the vision of God by the fact that they have a mission to fulfil on earth.

Without dwelling on the various passages in the New Testament where the doctrine of guardian angels is suggested, it may suffice to mention the angel who succoured Christ in the garden, and the angel who delivered St. Peter from prison. Hebrews 1:14 puts the doctrine in its clearest light: "Are they not all ministering spirits, sent to minister for them, who shall receive the inheritance of salvation?" This is the function of the guardian angels; they are to lead us, if we wish it, to the Kingdom of Heaven.

St. Thomas teaches us (Summa Theologica I:113:4) that only the lowest orders of angels are sent to men, and consequently that they alone are our guardians, though Scotus and Durandus would rather say that any of the members of the angelic host may be sent to execute the Divine commands. Not only the baptized, but every soul that cometh into the world receives a guardian spirit; St. Basil, however (Homily on Psalm 43), and possibly St. Chrysostom (Homily 3 on Colossians) would hold that only Christians were so privileged. Our guardian angels can act upon our senses (I:111:4) and upon our imaginations (I:111:3) -- not, however, upon our wills, except "per modum suadentis", viz. by working on our intellect, and thus upon our will, through the senses and the imagination. (I:106:2; and I:111:2). Finally, they are not separated from us after death, but remain with us in heaven, not, however, to help us attain salvation, but "ad aliquam illustrationem" (I:108:7, ad 3am).

APA citation. Pope, H. (1910). Guardian Angel. In The Catholic Encyclopedia. New York: Robert Appleton Company. Retrieved September 24, 2008 from New Advent: http://www.newadvent.org/cathen/07049c.htm

Dark Flow

As if the mysteries of dark matter and dark energy weren't vexing enough, another baffling cosmic puzzle has been discovered.

Patches of matter in the universe seem to be moving at very high speeds and in a uniform direction that can't be explained by any of the known gravitational forces in the observable universe. Astronomers are calling the phenomenon "dark flow."

The stuff that's pulling this matter must be outside the observable universe, researchers conclude.

When scientists talk about the observable universe, they don't just mean as far out as the eye, or even the most powerful telescope, can see. In fact there's a fundamental limit to how much of the universe we could ever observe, no matter how advanced our visual instruments. The universe is thought to have formed about 13.7 billion years ago. So even if light started travelling toward us immediately after theBig Bang , the farthest it could ever get is 13.7 billion light-years in distance. There may be parts of the universe that are farther away (we can't know how big the whole universe is), but we can't see farther than light could travel over the entire age of the universe.

Mysterious motions

Scientists discovered the flow by studying some of the largest structures in the cosmos: giant clusters of galaxies. These clusters are conglomerations of about a thousand galaxies, as well as very hot gas which emits X-rays. By observing the interaction of the X-rays with the cosmic microwave background (CMB), which is leftover radiation from the Big Bang, scientists can study the movement of clusters.

The X-rays scatter photons in the CMB, shifting its temperature in an effect known as the kinematic Sunyaev-Zel'dovich (SZ) effect. This effect had not been observed as a result of galaxy clusters before, but a team of researchers led by Alexander Kashlinsky, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md., found it when they studied a huge catalogue of 700 clusters, reaching out up to 6 billion light-years, or half the universe away. They compared this catalogue to the map of the CMB taken by NASA's Wilkinson Microwave Anisotropy Probe (WMAP) satellite.

They discovered that the clusters were moving nearly 2 million mph (3.2 million kph) toward a region in the sky between the constellations of Centaurus and Vela. This motion is different from the outward expansion of the universe (which is accelerated by the force called dark energy).

"We found a very significant velocity, and furthermore, this velocity does not decrease with distance, as far as we can measure," Kashlinsky said. "The matter in the observable universe just cannot produce the flow we measure."

Inflationary bubble

The scientists deduced that whatever is driving the movements of the clusters must lie beyond the known universe.

A theory called inflation posits that the universe we see is just a small bubble of space-time that got rapidly expanded after the Big Bang. There could be other parts of the cosmos beyond this bubble that we cannot see.

In these regions, space-time might be very different, and likely doesn't contain stars and galaxies (which only formed because of the particular density pattern of mass in our bubble). It could include giant, massive structures much larger than anything in our own observable universe. These structures are what researchers suspect are tugging on the galaxy clusters, causing the dark flow.

"The structures responsible for this motion have been pushed so far away by inflation, I would guesstimate they may be hundreds of billions of light years away, that we cannot see even with the deepest telescopes because the light emitted there could not have reached us in the age of the universe," Kashlinsky said in a telephone interview. "Most likely to create such a coherent flow they would have to be some very strange structures, maybe some warped space time. But this is just pure speculation."

Surprising find

Though inflation theory forecasts many odd facets of the distant universe, not many scientists predicted the dark flow.

"It was greatly surprising to us and I suspect to everyone else," Kashlinsky said. "For some particular models of inflation you would expect these kinds of structures, and there were some suggestions in the literature that were not taken seriously I think until now."

The discovery could help scientists probe what happened to the universe before inflation, and what's going on in those inaccessible realms we cannot see.

The researchers detail their findings in the Oct. 20 issue of the journal Astrophysical Journal Letters.