Even the simpler question is difficult to answer, but it is estimated that there are hundreds of billions of galaxies. The researchers use the Hubble Space Telescope to photograph a small section of the sky in depth and multiply the number of galaxies that appear in it by the number of these areas that cover the entire sky
Astronomers believe that there are hundreds of billions of galaxies in the universe, but the exact number is unknown. But can astronomers at least know how many galaxies have even been discovered so far? It turns out that here too the answer is negative "we don't know" says Ed Churchwell, Professor of Astronomy at the University of Wisconsin in Madison. "We know that this is a very large number. In one image, for example, the attached image taken by Hubble's ultra-deep field camera, about ten thousand galaxies can be counted.
In comparison to the Milky Way, our galaxy has between 100 and 300 billion stars. While this number won't change much, the number of galaxies we see increases with each improvement in our telescopes, and with the ability to see further back in time.
"To count them all we would have to look far enough or deep enough in space to see the galaxies in their formation." says Churchwell. "We have not reached that point now."
The estimation of the number of galaxies in the universe is done by counting the number of galaxies we can see in a small area of the sky. This number is used to estimate how many galaxies there are in the entire sky.
Currently, the estimate of hundreds of billions is derived from Hubble's Deep Field Camera images taken in 2003-2004. The camera looked at one area in the sky for several months - a point covering an area of less than one-tenth of a millionth of the sky - and thus Hubble was able to take pictures of galaxies 13 billion light-years away.
"You look at the pictures and ask, how many galaxies can you see?" Says Churchwell, "And it turns out to be a very large number." Then you take the number of galaxies in a piece of sky the size of a postage stamp and multiply that by the number of stamps covering the whole sky," says Churchwell, "and so it must be a much larger number."
In the first image from Hubble's Deep Field Camera, taken in 1995, you can see about 3,000 galaxies.
42 תגובות
Wants to know about the moon's low tide and the moon's position between the earth's sun. The location of our galaxy in space, orders of magnitude and distances. Requests to come to the Weizmann Institute to gain knowledge in everything related to this subject. Is it possible and how do you do it? Thanks Yitzhak 0533518978
100 billion galaxies
lol There are 700 billion galaxies in the universe.
I like this
The universe consists of spaces of matter and void when there is a constant balance between them, that is, their movement 10 million years ago repeats itself every fixed period of time and the galaxies move in circles that repeat again and again. Beyond the visible there are time dimensions that can be passed through when passing through the pillars of light. Question: If a spaceship doubles its speed every 30 minutes, assuming it doesn't collide with any object, what speed will it reach? Answer: Space speed is the maximum speed before moving to another time dimension.
I think it's fire! :)
Sabdarmish,
I was wrong about your example. You have taken up a finite mass in an infinite universe. In my words, I was referring to the assumption of an infinite universe with infinite mass that it is not immediately possible to determine whether we will be "dazzled" due to an infinite number of suns, or whether there will be "darkness" due to the lack of effect of the number of suns in relation to the infinite space, or something in between as in our reality. In other words, from the claim that "clarifies and clarifies" it is not possible to conclude that the universe is finite and the amount of matter in it is finite in my opinion.
To Eyal
If homogeneity exists then an infinite universe will also have infinite mass.
Proof: in an infinite universe there is a collection of volume units that, due to the principle of homogeneity, each of them has at least an equal amount of mass M and hence, the total mass in the universe is M multiplied by an infinite number of universe units, which is infinite mass.
If you manage to refute this Eyal, we'd love to hear it.
good evening
Sabdarmish Yehuda
Now I noticed that Sabdarmish's last message is one of many examples of the border issue. In fact he built a convergent column (summed infinite terms and got a finite sum). But by and large it doesn't have to be like this and the homogeneity doesn't have to be broken.
A. Ben-Ner:
Regarding the difficult question: matter and energy, as we know, are two sides of the same coin. So you can describe to you a space that contains matter in the form of energy (you can point to the first moments of the big bang in this theory perhaps). Then I ask: if energy exists in space without matter (and it does) then does that mean that a universe without curvature at all is possible? just a question.
Clarifies and clarifies:
It is difficult for me to agree with this explanation for the claim of the finitude of the universe and the matter in it: if the universe is infinite and also the amount of matter is infinite, who said that the infinity of matter outweighs that of space? As we know, there is such a thing called the rate of aspiration to infinity and of course a finite limit to the "play" between two factors aspiring to infinity. Therefore it is impossible to know from the assumption of infinity of space and matter whether (on average) we will be "blinded", whether there will be darkness or something constant in the middle.
You can do a mental exercise of an infinite universe in which the mass is finite. We will build it as follows:
A sphere with a diameter of R billion light years contained in a sphere with a diameter of two billion light years contained in a sphere with a diameter of three billion light years and so on ad infinitum.
We will determine the amount of mass in a different way - in the first ball, half a mass M, between the first and two-quarters of a mass M, between the second and third an eighth of a mass M, between the third and a fourth one-sixteenth, and so on. This universe will be infinite and the mass in it is finite (M)
But... it will not meet the principle of homogeneity
good evening
Yehuda Sabdarmish
First of all, on Thursday, August 20.8.09, 21 at 30:XNUMX p.m., your faithful servant is going to give a lecture at the observatory in Givatim on the topic "Dark thoughts about dark mass", you are all invited.
And for our purposes, indeed Michael you are right and in this case we have an agreement. The cosmological principle is nothing more than a wishful thinking of cosmologists, and of course if a deviation from this "principle" is discovered then it must be replaced by something else.
And by the way, deviations from this "principle" are already being discovered. For example, there are deviations in the background radiation that reaches us from different directions.
But, Ben Ner, your question is broader and I will answer you after thinking.
Good Day
Sabdarmish Yehuda
A.B.N.
Surely it is possible to have space without matter, otherwise everything would be full of matter!
Your statement about the homogeneity is strange. The basis of the theory for the formation of the universe is inhomogeneity, you must have seen the picture created by WMAP regarding the temperature variation in the background radiation. Galaxy clusters and VOID regions are proof of inhomogeneity in cosmological sizes. What does your isotropic claim have to do with space? If I'm in Tel Aviv and you're in Haifa, it's not possible to determine which of us is closer to Jerusalem? Of course the location is important!
The amount of material is finite, and the matter was proven with a logical argument a very long time ago :-). The claim is that if the amount of matter was infinite then there would be an infinite number of light emitting stars (sun star). If there were infinite suns then we would see blinding light coming from all directions. This does not happen, and hence the universe is finite and the amount of matter is finite.
The cosmological constant speaks of empty energy, alternatively it can be said that Higgs particles are not required to establish space.
A. Ben-Ner:
You are right, but you have to remember that the matter of homogeneity and isotropy is only an assumption.
The situation you describe, if it exists, would contradict this assumption but that doesn't mean it's impossible - it just means that if it turns out to be the case then the homogeneity and isotropic assumptions are incorrect.
By the way, I assume that Yehuda will embrace these things warmly because he always claims that the cosmological principle is not to be trusted.
Goodbye to Yehuda Sabdarmish.
Your answer to my question here is of a mathematical nature and as such it is certainly correct. However, I mean here the physical aspect. Here I see a problem. I will try to explain, on the one hand, as far as I know, the basic premise of cosmological research is that the universe is homogeneous = (uniform in its composition in cosmological KM) and isotropic = (there is no preference for any observation point).
From this assumption it necessarily follows (and please correct me if the assumption is wrong) that if space is infinite then the number of galaxies and the matter in it is also infinite.
On the other hand, our elementary imagination, while it cannot grasp the concept of the finitude of space (what is beyond space?) it can (at least so it seems in initial thought) grasp the concept of the finitude of the amount of matter in space.
And now a (difficult) question:
Is it even possible for space to exist without matter?
No. Ben-Ner Shalom
Regarding your question: Is it possible that, even though the universe is infinite, the number of galaxies in it is a finite number?
Well the answer is that it is possible, because an infinite group can always have a partial group that is finite.
For example
Can you describe an infinite universe different from ours, which has only one galaxy? Sure, why not!
Hence, any number can be the amount of galaxies.
good evening
Yehuda
Thank you very much point and anonymous user
You broke a stupid stigma for us guys
epic:
Definitely can be.
By the way, I assume you meant to write that the galaxy is 10 billion *light years* away from us (and not 10 billion *years* which is a measure of time at all).
a question
If a galaxy is 10 billion years away from us then we see it as it is
was 10 billion years ago, so it may have changed or disappeared completely during all this vast time, so it may be that this galaxy does not exist even though
Do we see her?
There were 6 NASA missions to the moon, a total of 24 flew to the moon, and 12 of them walked on the moon. I don't know how many of them were the same astronauts who came back to visit..
The distance to the moon is about 380 thousand km, so this is the maximum distance for a manned spacecraft.
Check here, I may have made a slight mistake in the numbers:
http://en.wikipedia.org/wiki/Apollo_program
12 from Apollo flights 11,12,14,15,16, and 17
17 including the Apollo 13 rocket that did not return.
http://wiki.answers.com/Q/How_many_people_landed_on_moon_so_far
and their names:
http://en.wikipedia.org/wiki/Template:People_who_have_walked_on_the_Moon
Regarding the spaceship, when those spaceships circled the moon and reached the farthest part from the earth, then the distance was the greatest that a person was. I don't know how long the coffee took, depending on the speed.
And the unmanned spacecraft has already left the solar system ..Viagar I think.
Hello, I'm Micha and I'm sorry to interrupt the discussion like this
But I have an unrelated question
How many people walked on stars?
Except for Neil Armstrong, and Khortzik II, in Apollo 11
What is the maximum distance a manned spacecraft has ever flown, and how long did it take?
Thank you and sorry
Correction - "between tens of billions and hundreds of billions"
Avi, in the title of the article it is written that "it is estimated that there are tens of billions of galaxies", and then it is written that "astronomers believe that there are hundreds of billions of galaxies in the universe".
There is a "little" difference between tens of billions despite billions.
A. B. Ner
A. I think the universe is not infinite. By the way, it is customary to quantify the number of atoms in it around 10 to the 80th power.
B. Let's say your idea was true, recognizing that it is the same galaxy shouldn't be a problem. Each galaxy has a number of unique characteristics such as temperature (eminent wavelength), pulsars with known cycle times and more. They would get over it very quickly.
Point, the fact that people die is not a problem at all.
People have no uniqueness in the whole universe that makes it worthwhile to keep them alive. Meanwhile they do more harm than good.
I simply think what happened at time 0 is much more interesting than knowing exactly what the number of galaxies is and exactly what the number of stars is
It is only possible to know the number of galaxies that are within a radius of 13.4 billion light years as they existed billions of years ago
Since the universe is larger than the size of the observable universe as a result of the inflation phase that was in the initial phase of the universe's development
Erid, to know what happened at time 0,
Why is this so important?
It is said that we know today what happened after Planck time
And in another 10.5 years we will know what happened at time 0
Will it change our sad situation?
After all, people are still dying.
If we could bring the light of our galaxy back to us, we could see the history of our planet like on television. For example, we could watch the real dinosaurs, or for example, check all the Bible stories in real time and see what is true and what is fiction, and more... a wonderful world.
Ben-Ner..
It is difficult for me to think of a way in which it is possible to think about something in physics and in general in terms of logic that something would have an actual infinite size.
And why is it so important?
It is said that 656 billion galaxies are known today
And in another 10.5 years the number will rise to 1129 billion
Will it change the age of the universe?
After all, we still don't know what happened at time 0.
and another question (unanswered)
Is it possible that, although the universe is infinite, the number of galaxies in it is a finite number?
to Gil Dotan. Tam answer.
Very interesting question. Of course, the easiest and most likely answer to your question is no, however, as a continuation of my previous response (10) where I mentioned the idea of the "curved universe" then...
Under certain conditions of a curved universe, it seems to me that it is possible to see the same galaxy twice, but each time we will have to turn our gaze in opposite directions, for example to the east and the west. When we look to the east we can see the galaxy from some distance and at some age and when we look to the west we can see it from the other side of the universe and then it will show us from another distance and time
Other. the question is………
How do we know it's the same galaxy???
Dear Friends
You all must have heard that there is still the possibility that the cosmic space-time is curved. If indeed it is so, then it is possible that, if such sophisticated means of observation are developed then when we observe far-far-far-far…………..we will be able to see our galaxy, the Milky Way, as it looks out at us from the other side of the curved universe. From that side it will appear to us as if it is moving away from us very quickly and this is due to the expansion of the universe.
The question is over:
Is it possible to see the same galaxy at different times?
After all, from a certain distance we see embryonic galaxies that existed when the universe was still young.
I just found and came to write the same link...
What amazing pictures are there huh?
Look
http://hubblesite.org/gallery/wallpaper/pr2007017a/
And anyway
http://hubblesite.org/gallery/wallpaper/
pleasure…
Link to the image from the Hubble website (can be downloaded as a wallpaper
http://hubblesite.org/gallery/wallpaper/pr1996001a/
And the size of the universe is not known to us at all, as we develop we will know more about its size, does this mean that actually this number is also very temporary - just because of the simple fact that we did not multiply by a correct multiple?
It would be more accurate to state in the title "the visible universe", the size of the universe depends on a theory, for example, there are theories that predict that the universe itself in relation to the visible universe is like the ratio between the size of the solar system and a grape.
As far as I remember the Milky Way has several hundreds of billions of stars. How did it reach 4 billion?
This is the picture that appeared in Universe Today. I assume it is on Hubble's website in 30 megabytes as well, if you find it, I would appreciate it if you could upload the link. I can only deal with it tomorrow. Anyway, if you click on the sign of the frames inside the caption, you can see it in its full possible size.
Is there a higher resolution of this image?
I'm thinking of putting it on my desktop...