Australian, British and American astronomers have completed the most detailed survey of the nearest galaxies to the Milky Way up to two billion light years away
It took scientists ten years to produce the image on the left (Click here to enlarge) showing the galaxies around us (we are probably in the middle of the picture).
Every white dot in the image (at its full resolution) is a galaxy, and the image shown here is actually a side view of the full XNUMXD map.
The map was obtained by a sky survey called the "Six-Degree Galaxy Survey" or 6dFGS conducted using the British Schmidt telescope, in eastern Australia, which is 1.2 meters in diameter. The observatory is operated by British, Australian and American scientists.
The team checked not only the positions of the galaxies but also their motion, by precisely measuring the shift of the light coming from them to longer wavelengths (red-shift), a shift caused by the expansion of the universe. In the last ten years, the survey mapped the nearby universe with great precision and yielded spectral information on more than 100,000 (one hundred thousand!) galaxies. All information is open for download online.
And if the picture seems to you that something is missing: the two black triangles are caused by the fact that the Milky Way itself, and all the interstellar dust it contains, hides part of the sky. "Unfortunately we can't see the whole sky," says research team member John Lucy from the UK.
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57 תגובות
Melody T
The odds that the collision will occur in July is plus or minus 1 in 12, there is no commitment as to which year it is, nor is there a commitment that the name "July" will still be in use in any way, or that any name at all will be used by anyone or anything.
In any case, my diary at home is already prepared...
Thank you very much Michael and Yehuda,
Now I will sleep well at night 🙂
According to my calculations, the collision probably won't happen in July, so there's nothing to worry about.. 🙂
to the point
True [ and I couldn't calculate how much it grew due to gravity. There is no doubt that it depends on the relative speed of the galaxies at the moment of the collision, and of course also on the correctness of Newton's formula, which I do not follow at the great cosmological distances.
In addition, from simulations made regarding the collision itself, there will be stars that will enter the collision range several times and others will avoid this fate, on the other hand, there will also be some that will penetrate the entire length of the galaxy and their chance of being hit will be great.
But by and large, my calculation gives an estimate of the amount of collisions.
Good Day
Sabdarmish Yehuda
Yehuda, when you take into account the force of gravity, the cross-sectional area for impact increases
Composed by T. Valmichel and others
Below is a rough calculation:-
The cross-sectional area of a hundred billion stars in the Milky Way is about the cross-sectional area of a hundred billion stars of average size of our sun, because the radius of the sun is less than three light seconds, the cross-sectional area is about 30 square light seconds. And of the whole hundred billion is about 3 million million square light seconds.
The radius of the galaxy is about 50000 light years, therefore its cross-sectional area is about 9 million million million square light seconds
Hence, the chance of a star from Andromeda colliding with a star in the Milky Way is one in three million, but Andromeda has about three hundred billion stars, so during the collision of the two galaxies, the number of stars that will collide will be of the order of a hundred thousand stars!
Hence the chance of it being our sun is one in a million.
You can sleep peacefully
good week
Sabdarmish Yehuda
Chen T:
It is very likely that there will be collisions between stars and also that there will be changes in star orbits.
I read somewhere (in an article on this website) that our solar system will probably be outside the dangerous zone.
We will live and see 🙂
Hello Michael 🙂
When Andromeda merges on the Milky Way, will there be collisions of stars, and the orbits of the stars will change, or will the gravity / attraction of each star by itself prevent such situations and one galaxy will simply be formed, a simple connection of the two galaxies with a slight change of orbits?
fresh:
It's not a matter of wording.
As mentioned - he did not address the question you asked at all.
So apparently formulating a claim is no less important than software
fresh:
It is hard for you to notice that it is the same thing because it does not at all (but at all!) refer to gravitational or electromagnetic collapses but only to the expansion of the universe, but it does explain that it is a transition from low-probability states to high-probability states.
fresh:
He says exactly what I said
Michael and Point,
The above link offers an interesting explanation as to why entropy is constantly increasing despite the apparent increase in the patterning and complexity of the universe which is only increasing and thus apparently violates the principle of entropy increase, the explanation is that the very fact that our universe is expanding and growing all the time increases entropy to a greater extent than the effect of reducing entropy that the pattern/complexity causes.
And this is probably why the entropy principle is preserved.
http://www.tapuz.co.il/blog/ViewEntry.asp?EntryId=1126168
Ori:
You didn't "look" at the balloon well enough.
In which direction do the dots move on the surface of the balloon?
Each moves away from her friend to the same cause that separated them in the first place.
A point that is to my right will move away to the right and a point to my left will move away to the left and so on for any other direction - and so on for others and not only for
There is no preferred direction!
When I said that the "universe balloon" has no inner part I should also have added that it is not surrounded by an outer part.
I mention this as a response to your possible claim that in the balloon all the points move "out".
So that's it - there is no other way.
Uri, the general direction of all things in the world is the future. Everyone is moving in the direction of the future. And as for the galaxies, if they are all moving away from each other how can you define a direction
Also add the following fact, that if the shape of the universe is a sphere, it means that if you somehow went very fast in a certain direction then you would come back on the other side (perhaps with your structure changing from left to right), for example it is possible that if the universe had a certain shape then we could see ourselves At the edge of the universe, like we were at the end of the big inflation.
Michael, thanks for the answer. I can relate to the idea of there being nothing in the middle of the balloon. Still my argument says that the expansion and acceleration of the 'points' (galaxies) should be 'together' in a common general direction with a deviation from each other.
An inflating balloon does not get deformed in one of its directions unless it explodes! On the same conceptual (not mathematical) basis I think my expectation is to see this group of a hundred thousand galaxies traveling in the same general direction in light of the Big Bang theory.
Isn't that so? Does the mathematics of this model explain that there is a situation in which galaxies will move towards each other at great distances (referring to distances where their gravity does not have an effect on themselves - that they do not attract each other I mean - like the Milky Way and Andromeda for example)?
Has anyone found on this survey site the place where they show the direction of motion of the surveyed galaxies???
Uri will add to the complexity the following fact, the farther you look in space, the farther you look in time, that is, the end of the visible universe is in some sense the big bang... (which is not really true, because the expansion in the early universe was above the speed of light and this took the big bang out of to our event horizon (visible horizon).
Ori:
Point has already given you the best illustration.
Consider the face of a balloon:
Dots on an inflatable balloon move away from each other faster the further apart they are.
The retirement of the stars is indeed three-dimensional, but it can be seen - in a certain sense - as the tongue of a four-dimensional balloon.
Now - not only is it difficult for a non-mathematician to imagine what the term "four-dimensional balloon" means, but those who try to imagine the universe must think of a four-dimensional balloon whose interior has nothing - not even space - in fact it has no interior.
It is difficult because our imagination has not evolved to perceive such situations and the only way we have to deal with them is mathematics.
If the universe is in the shape of a sphere, you are right, but this is unknown and therefore we do not know if there is a middle or not.
My logic and the desire for simplicity says that he is like that, but as I said, it is unknown.
I understand there are 4 dimensions, although I was paying attention to catch that.
Still, the very definition 'expansion' as I understand it is that each point is constantly moving away from all the other points - increasing its range from the other points at every centimeter of its diameter.
If the previous sentence is true and the size of the universe is such that there are parts that are so far from us and perhaps move at a speed relatively higher than the speed of light and therefore we do not see them, then the part that we do see should move in the same general direction while the movement between the parts in it (the galaxies under observation) should increase the range by one from the second or at least a group of related galaxies from other groups.
Regarding Gil Dotan's answer, even if it was a very small point - everything spreads from that point on. Otherwise, what caused 'part' of the matter galaxies to change their direction and move opposite to the direction of expansion?
Uri, as on the surface (area = 2 dimensions) of a sphere (3 dimensional) there is no center, and the center exists only in the center of the three dimensional sphere. Thus on the surface of the space (3 dimensions) of the universe (4 dimensions) there is no center, the universe is space-time, and not space as we are used to imagining, the question whether the 4 dimensional universe has a center or not depends on the question of the shape of the universe.
There is no middle point.. the whole space expands and since it was compressed in such a small point, then the "middle" is irrelevant.
But if they are all moving away from each other, this means that the center of the observation is the place where the big bang took place - which is most likely not the case at all... I would expect to see them all moving towards a certain vessel when there is also an expansion of this entire cloud which creates the distance of all of them from all of them (by and large) like In a three-dimensional funnel where the movement is from the nozzle to the large opening.
Does anyone know what they saw in the observations themselves - in practice????
By and large, they are all moving away from each other, but the galaxies also have their own motion, for example - the Andromeda galaxy, our neighbor, actually approaches the Milky Way galaxy.
good evening
Sabdarmish Yehuda
They all move away from each other. This is due to the expansion of the universe and space.
I will clarify my question:
The article stated that the redshifts of all 100 galaxies surveyed were measured.
What I asked is this - do the surveyed galaxies all move in the same general direction? In order to support the big bang theory, it is appropriate, in my naive understanding, that they should be in the same direction - from the point of the big bang onwards? not like that?
This is what I meant in my question, since in the most superficial inspection I did on the survey's website, I did not find a simulation of the direction of movement of the galaxies (I called them points).
To be created: created in the shadow or in Tselem :)?
Michael R.,
A. You are doing holy work here. I take my hat off... you are the ultimate answer to all the troublemakers and a reliable source of knowledge to all the curious.
B. Allow me to make a reservation about one thing you claimed... in my humble opinion (as a physicist) the question 'why?' It is very relevant and interesting, but the answers to this question do not come easily and usually not in abundance, but to those who know Han.
Because of Uri's response (which I think he should clarify more if he wants to get an answer to it) I came back here and saw response 26 of a point.
The claim in this response is not entirely accurate.
The geometry is a local matter and it can change from place to place - mainly due to the influence of the mass that is in the vicinity of that place.
It is true that the entire universe can be open or closed and this is determined as a function of the distribution of mass in the entire universe, but this is only one aspect of the geometry of the universe.
Does anyone know where these points go?
Are they all moving in the same direction?
Do they move away from a certain point?
fresh,
The geometry of the universe (it is a 4-dimensional geometry) is derived directly from the figure of the average density in the universe, in relation to the critical density.
If the average density is greater than the critical one, then the universe is closed and in the shape of a sphere 4 etc.
And the whole question is what is the average density of the universe.
fresh:
I assume that you asked a question that you thought was rhetorical and that you only did it for the sake of arguing, but your question has an answer.
If you don't want to actually learn, I suggest you at least read the book "Poincare's Conjecture" to get some idea.
Just for example - one of the methods is measuring the sum of the angles in a triangle.
But what they "feel" is indeed the geometry of the universe and not its shape.
And how do the scientists "feel" the geometry of the universe and develop theories and articles about it?
This is not a strange point of view.
What gives the room its shape is the wall.
A room with three flat walls (plus ceiling and floor) will actually be in the shape of a triangular prism and not in the shape of a cube.
If you have no way of feeling the walls of the room - you cannot know what its shape is.
I understand exactly what you meant, you meant that you are foiling the universe as if it were the "wall". And it is not clear why you choose such a strange point of view.
fresh:
I am stopping this discussion here because it seems to me that you are not even close to understanding my intentions and the issue is not important enough for us to waste any more time on it.
I can imagine more reservations that will come up and the answers that I will have to give and the whole business will go on beyond the time that is worth devoting to it.
fresh:
You didn't understand my words.
When you are inside the room you are outside the wall so you can see the shape of the wall and that is what you are drawing.
Michael:
False, if you are locked inside a room and cannot see that room from the outside, you can still tell that the room has the shape of a cube.
fresh:
I explained why not - at least according to the interpretation I give to the word "form".
A form is a thing to draw (note the common root of the two words).
You can only paint what you can see and we can only see something when we are not part of it.
As I explained - the fact is that you don't even manage to draw the "shape" that the article talks about and have no choice but to draw some kind of shape that conveys only part of the information about the geometry but not all of it.
And if you measure the universe "from the inside" can't it have a shape?
fresh:
First of all, you should understand that the word "semantic" is derived from the word "semantics" which means... meaning.
Therefore "semantic" is always "meaningful".
There is a difference that I tried to explain between what you call "shape" (which is something you see from the outside) and "geometry" which is what can be measured from the inside.
The entire universe has no shape because it cannot be seen from the outside and one can only try to get an illustration of its geometry through various "shapes" that one tries to sketch.
As you can see - these shapes don't really manage to describe things correctly and therefore they create situations that seem paradoxical like a spaceship that goes from one side of the funnel to the other side or even two people walking on both sides of the funnel while holding each other's hand.
Funnel shape Funnel geometry, it's semantic. The question is whether there is an essential non-semantic difference between "funnel shape" and "funnel geometry"?
After all, even if according to your claim the universe is not inside any space and is all the space there is (which is a theory that can definitely be true), then it too has a form. Why do you think that everything that exists cannot have form?
point:
"Why" is in short why.
Of course I don't have any answer to the question, but even if I had pointed to a reason, it would have been possible to ask about the reason for the reason. Therefore, we will probably never be left with questions as to why that we have not yet answered.
fresh:
In the link you provided, it is not about the shape of a funnel as you perceive it, but rather the geometry that describes the entire space (ie - not a shape of a funnel that is inside some normal three-dimensional space - note that this is a reservation that also appeared in my previous response).
Also the drawing there where you see the spaceship making its way to the "edge of the funnel" on one side and then continuing on the other side indicates that this is not a structure you would call a "funnel" at all. All in all, it is an attempt to create a more tangible illustration of the curvature of space at its various points.
Michael I meant for what and not for what.. my mistake in the lack of clarification.
Michael
Regarding the funnel
https://www.hayadan.org.il/funneluni-190404/
anonymous:
The word "why" includes an assumption that the question you are asking is without any basis.
The question "why" assumes that things have a certain purpose and now all that remains is to find out what it is - this while we have no indication that anything in nature exists "for" something.
And why does all this even exist?
And why does all this even exist?
fresh:
First of all - I don't know who claims that the universe is funnel-shaped. I don't think there is a scientist who claims that.
Can you point to a quote from a serious scientist who claims this?
In fact - as far as current science perceives the universe - there is no meaning at all to talk about its "shape" - as if it were housed in some other space since the universe is all the space there is.
You can brag a lot more trying to explain what I said above, but it is even more important to understand that what was said does not discuss the shape of the universe at all!
The article deals with what we measured in a sphere with a radius of two billion light years around us.
Is this the shape of the universe? I mean a spherical universe? There is a claim that the universe is shaped like a funnel, a horn, a ball, or a pretzel. There are many theories on the subject.
The thing that sucks the most is that we only have 100 years at most to be here.. We will never see anything except our ball.
Just unbelievable how big our universe is.
Ariel:
You probably didn't read the article carefully.
The "empty" part - what you call two rays - is what is hidden by the Milky Way itself. It is written in the article. We can see galaxies throughout the universe except those in the Milky Way's Milky Way region (because in those directions the stars and interstellar gas of the Milky Way block our ability to see outside the Milky Way).
The answer to your first question is also written - although not explicitly.
It says that the image is "a view from the side on the XNUMXD map".
The XNUMXD map is - obviously - shaped like a ball and a sphere - when you look at it from the side - thicker as you get closer to the center of its projection - and thinner as you get closer to the edges.
Of course, in a thicker region it is expected to find more galaxies.
Another question,
Why is there a spring with two "rays" that do not contain galaxies? Couldn't these places be measured because of traffic?
If I understand the visualization correctly we are in the center of the sphere. The distribution of galaxies around us looks like there are more galaxies in the center and fewer as you move away from the center. Does it look like we're at the center of the universe? Or maybe the same simulation would have been obtained from each galaxy we selected?