How many galaxies are there in the universe

Except you are. When you see the sky in microwaves, it does indeed glow in all directions. It turns out the Universe has 10 times more galaxies than previously estimated — 2 trillion galaxies. Not 10 times the stars or mass, those numbers have stayed the same. And, once James Webb launches, those numbers will be fine-tuned again to be even more precise.

Stay tuned for the better number. Podcast audio : Download Duration: — 2. Podcast video : Download Duration: — If there are that many galaxies in this Universe, how many stars are there likely to be?

This makes the probability of an Earth similar to our own or even many Earth like planets extremely likely. What does it say about the idea of a God over everything and the nature of such a God? What does it say about the idea of a beginning of the Universe and the end of a Universe in finite time? That is predicted by religions.

Specifically the Alpha and Omega, the beginning and the end. Does it account for 11 dimensions as specified by physics people? The current expansion of time and space is theory of course. Another theory might be one in which entrophy would have different rules of time and space. The best attempt we ever made was the Hubble eXtreme Deep Field XDF , which represented a composite image of ultraviolet, optical, and infrared data.

By observing just a tiny patch of sky so small it would take 32 million of them to cover all the possible directions we could look, we accumulated a total of 23 days worth of data.

Stacking everything together into a single image revealed something never-before seen: a total of approximately 5, galaxies. This represented the highest density of galaxies ever observed through a narrow, pencil-like beam in space.

But even with all the power of Hubble, and all the magnification of gravitational lensing, there are still galaxies out there beyond what we are capable of seeing. You might think, therefore, that we could estimate the number of galaxies in the Universe by taking the number we observed in this image and multiplying it by the number of such images it would take to cover the entire sky. In fact, you can get a spectacular number by doing so: multiplied by 32 million comes out to an incredible billion galaxies.

But that's not an estimate; that's a lower limit. Nowhere in that estimate do the too-faint, too-small, or too-close-to-another galaxies show up. Nowhere do the galaxies obscured by the neutral gas and dust appear, nor do the galaxies located beyond the redshift capabilities of Hubble.

Yet, just as those galaxies exist nearby, they ought to exist in the young, distant Universe as well. Galaxies comparable to the present-day Milky Way are numerous, but younger galaxies that are Milky For the first galaxies of all, this ought to be taken to the extreme, and remains valid as far back as we've ever seen.

The big ingredient that we need to come up with a true estimate, then, is how structure accurately forms in the Universe. If we can run a simulation that starts with:. We can simulate when stars form, when gravity pulls matter into large enough collections to create galaxies, and to compare what our simulations predict with the Universe, both near-and-far, that we actually observe.

Perhaps surprisingly, there are more galaxies the early Universe than there are today. But unsurprisingly, they're smaller, less massive, and are destined to merge together into the old spirals and ellipticals that dominate the Universe we inhabit at present. The simulations that match best with reality contain dark matter, dark energy, and small, seed fluctuations that will grow, over time, into stars, galaxies, and clusters of galaxies.

Most remarkably, when we look at the simulations that match the observed data the best, we can extract, based on our most advanced understanding, which clumps of structure should equate to a galaxy within our Universe. A simulation of the large-scale structure of the Universe. Identifying which regions are dense and When we do exactly that, we get a number that's not a lower-limit, but rather an estimate for the true number of galaxies contained within our observable Universe.

The remarkable answer? Yet, that number is so remarkably different from the lower-limit estimate we came up with from the Hubble eXtreme Deep Field image. In the background, distant galaxies can be seen with their stellar populations as well. Even though they're rarer, there are still late-time galaxies actively forming massive amounts of new stars. Over time, galaxies merged together and grew, but small, faint galaxies still remain today.

Even in our own Local Group, we're still discovering galaxies that contain mere thousands of stars, and the number of galaxies we know of have increased to more than The faintest, smallest, most distant galaxies of all are continuing to go undiscovered, but we know they must be there. For the first time, we can scientifically estimate how many galaxies are out there in the Universe.

The next step in the great cosmic puzzle is to find and characterize as many of them as possible, and understand how the Universe grew up. I have won numerous awards for science writing. I have won numerous awards for science writing since for my blog, Starts With A Bang , including the award for best science blog by the Institute of Physics. Follow me on Twitter startswithabang. The result was an estimated 3, faint galaxies in a single frame, going as dim as 30th magnitude.

For comparison, the North Star or Polaris is at about 2nd magnitude. This image composite was called the Hubble Deep Field and was the farthest anyone had seen into the universe at the time. As the Hubble telescope received upgrades to its instruments, astronomers repeated the experiment twice. In and , scientists created the Hubble Ultra Deep Field, which in a million-second exposure revealed about 10, galaxies in a small spot in the constellation Fornax.

In , again using upgraded instruments, scientists used the telescope to look at a portion of the Ultra Deep Field. Even in this narrower field of view, astronomers were able to detect about 5, galaxies.

Researchers dubbed this the eXtreme Deep Field. All in all, Hubble reveals an estimated billion galaxies in the universe or so, but this number is likely to increase to about billion as telescope technology in space improves, Livio told Space. Whatever instrument is used, the method of estimating the number of galaxies is the same. You take the portion of sky imaged by the telescope in this case, Hubble.

Then — using the ratio of the sliver of sky to the entire universe — you can determine the number of galaxies in the universe. That is the cosmological principle. The principle dates back to Albert Einstein's theory of general relativity. Einstein said that gravity is a distortion of space and time. With that understanding in hand, several scientists including Einstein tried to understand how gravity affected the entire universe.

This is called the cosmological principle. One example of the cosmological principle at work is the cosmic microwave background , radiation that is a remnant of the early stages of the universe after the Big Bang. Measurements of the universe's expansion — through watching galaxies race away from us — show that it is about As the universe gets older and bigger, however, galaxies will recede farther and farther from Earth. This will make them more difficult to see in telescopes.

The universe is expanding faster than the speed of light which does not violate Einstein's speed limit because the expansion is of the universe itself, rather than of objects traveling through the universe.

Also, the universe is accelerating in its expansion. This is where the concept of the "observable universe" — the universe that we can see — comes into play. In 1 trillion to 2 trillion years, Livio said, this means that there will be galaxies that are beyond what we can see from Earth.