Hubble eXtreme Deep Field

There Are At Least 10 Times More Galaxies In The Universe Than We Thought

The universe suddenly looks a lot more crowded.

Waaaaay back in 1995, the Hubble Deep Field images surprised the world by revealing how crammed the universe is with galaxies. At that time astronomers estimated there were about 200 billion galaxies in the universe. Recent estimates put that count closer to 2 trillion, at least 10 times as many galaxies as we thought. However, about 90% of the galaxies in the observable Universe are actually too faint and too far away to be seen or studied. Phil Plait explains:

Now, let me be clear. This doesn’t meant the Universe is ten times bigger than we thought, or there are ten times as many stars. I’ll explain — I mean, duh, it’s what I do — but to cut to the chase, what they found is that there are lots of teeny, faint galaxies very far away that have gone undetected. So instead of being in a smaller number of big galaxies, stars are divvied up into a bigger number of smaller ones.

And it doesn’t mean the Universe has 10 times more mass than we thought. The mass is the same, it’s just distributed differently than we thought. It’s like knowing there are 1 million people in a city, and finding out they live in 100,000 buildings when you thought they were only in 10,000. There are more buildings, but not more people

This discovery has also helped lead to explanations for Olbers’ paradox which states, “Why is the sky dark at night if the universe contains a multitude of stars?” NASA helps explain:

The team came to the conclusion that indeed there actually is such an abundance of galaxies that, in principle, every patch in the sky contains part of a galaxy. However, starlight from the galaxies is invisible to the human eye and most modern telescopes due to other known factors that reduce visible and ultraviolet light in the universe. Those factors are the reddening of light due to the expansion of space, the universe’s dynamic nature, and the absorption of light by intergalactic dust and gas. All combined, this keeps the night sky dark to our vision.

The sky is literally covered in galaxies! Mind boggling to be sure!

Hubble eXtreme Deep Field

Hubble eXtreme Deep Field

Hubble eXtreme Deep Field
Image courtesy of NASA

NASA has recently released a new Deep Field image called eXtreme Deep Field (XDF) that improves on the older Ultra Deep Field (UDF) image. The XDF is the deepest image of the sky ever obtained and reveals the faintest and most distant galaxies ever seen. This image is a composite of nearly ten years worth of photographic exposures taken by the Hubble Space Telescope – over 2,000 photographs totaling 22.5 days worth of total exposure time. Nearly everything you see in the picture is a galaxy containing billions of stars.

The new full-color XDF image reaches much fainter galaxies and includes very deep exposures in red light from Hubble’s new infrared camera, enabling new studies of the earliest galaxies in the universe. The XDF contains about 5,500 galaxies even within its smaller field of view [than the UDF]. The faintest galaxies are one ten-billionth the brightness of what the human eye can see.

The universe is 13.7 billion years old, and the XDF reveals galaxies that span back 13.2 billion years in time. Most of the galaxies in the XDF are seen when they were young, small, and growing, often violently as they collided and merged together. The early universe was a time of dramatic birth for galaxies containing brilliant blue stars extraordinarily brighter than our sun. The light from those past events is just arriving at Earth now, and so the XDF is a “time tunnel into the distant past.” The youngest galaxy found in the XDF existed just 450 million years after the universe’s birth in the big bang.

Click on the image above for the gigantic 1.4MB image. And keep looking up.

A list of Events Taking Place In The Very Distant Future

Below is a list of events, given present scientific understanding and models, that are expected to occur in the far future. Entities affected include humans, the Earth, the galaxy and the known Universe. Predictions include the fields of biology, geology, astrophysics, cosmology, and particle physics. It should be noted that several alternate future events are listed to account for questions still unresolved.

  • 10,000 years from now – The end of humanity, according to Brandon Carter’s Doomsday Argument, which assumes that half of the humans who will ever have lived have already been born.
  • 10,000 years from now – The Earth’s axial tilt reaches a minimum of 22.5 degrees. The Gregorian calendar will be roughly 10 days out of sync with the Sun’s position in the sky.
  • 25,000 years from now – The Arecibo Message, a collection of radio data transmitted on 16 November 1974, reaches its destination, the globular cluster Messier 13. This is the only interstellar radio message sent to such a distant region of the galaxy.
  • 50,000 years from now – Niagara Falls erodes away the remaining 20 miles to Lake Erie and ceases to exist.
  • 100,000 years from now – Proper motion (the movement of stars through the galaxy) will make today’s constellations unrecognizable.
  • 500,000 years from now – By this time Earth will have likely been impacted by a meteorite of roughly 1 km in diameter.
  • 1 Million years from now – Highest estimated time until the red supergiant star Betelgeuse explodes in a supernova. The explosion is expected to be easily visible in daylight.
  • 10 Million years from now – The widening East African Rift valley is flooded by the Red Sea, causing a new ocean basin to divide the continent of Africa.
  • 230 Million years from now – The solar system reaches Lyapunov time and the orbits of the planets become impossible to predict.
  • 240 Million years from now – From its present position, the Solar System will have completed one full orbit of the Galactic center.
  • 250 Million years from now – All the continents on Earth fuse into a possible new supercontinent.
  • 600 Million years from now – Tidal acceleration moves the Moon far enough from Earth that total solar eclipses are no longer possible. Carbon dioxide levels in its atmosphere decrease to the point at which C3 photosynthesis is no longer possible. 99% of all plants will die.
  • 1 Billion years from now – The Sun’s luminosity increases by 10%, causing Earth’s surface temperatures to reach an average of 47°C and the oceans to boil away.
  • 5.4 Billion years from now – The Sun becomes a red giant. Mercury, Venus and possibly Earth are destroyed. During these times, it is possible that Saturn’s moon Titan could achieve surface temperatures necessary to support life.
  • 7 Billion years from now – The Milky Way and Andromeda galaxy collide.
  • 14.4 Billion years from now – Sun becomes a black dwarf as its luminosity falls below three trillionths its current level making it invisible to human eyes.
  • 20 Billion years from now – The end of the Universe in the Big Rip scenario.
  • 50 Billion years from now – Assuming both survive the Sun’s expansion, by this time the Earth and the Moon become tidelocked, with each showing only one face to the other.
  • 100 Billion years from now – The Universe’s expansion causes all evidence of the Big Bang to disappear beyond the practical observational limit, rendering cosmology impossible.
  • 1 Trillion years from now – Low estimate for the time star formation ends in galaxies as they are depleted of the gas clouds needed to create stars. Once star formation ends and the least massive red dwarfs exhaust their fuel, the only stellar-mass objects remaining are stellar remnants (white dwarfs, brown dwarfs, neutron stars and black holes).
  • 2 Trillion years from now – All galaxies outside the Local Supercluster are no longer detectable in any way, assuming that dark energy continues to make the Universe expand at an accelerating rate.
  • 1015 (1 Quadrillion) years from now – Estimated time until stellar close encounters detach all planets in the Solar System from their orbits. The Solar System will no longer exist.
  • 3×1043 years from now – If protons decay, this is the estimated time for all nucleons in the observable Universe to decay. The Black Hole Era, in which black holes are the only remaining celestial objects begins.
  • 1065 years from now – If protons don’t decay this is the estimated time for rigid objects like rocks to rearrange their atoms and molecules via quantum tunneling. On this timescale all matter is liquid.

  • 101050 years from now – Estimated time for a Boltzmann brain to appear in the vacuum via a spontaneous entropy decrease.

  • 101056 years from now – Estimated time for random quantum fluctuations to generate a new Big Bang.

  • 101076 years from now – All matter collapses into black holes, again.

Current theories suggest that the Universe is open, and thus will not collapse in on itself after a finite time. However, the infinite future potentially allows for the occurrence of a number of massively improbable events, such as the formation of a Boltzmann brain. A more complete list from which the ones included here were taken can be found on Wikipedia.

No Beginning, No End, No Big Bang

Wun-Yi Shu (associate professor at National Tsing Hua University in Taiwan) has proposed a new universal model in which mass is converted into length and time is converted into space as the universe expands. As the universe contracts, the opposite occurs. The conversion factor depends varying gravitational “constant” and a varying speed of light (G/c2). Yeah, he also proposes that the speed of light is not constant.

However, his model explains “how the magnitudes of the three basic physical dimensions, mass, time, and length, are converted into each other, or equivalently, a novel theory about how the geometry of spacetime and the distribution of mass-energy interact. The theory resolves problems in cosmology, such as those of the big bang, dark energy, and flatness, in one fell stroke.”

Big Bang-less models are gaining popularity among cosmologists.