Einstein's 'Biggest Blunder' Turns Out to Be Right


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What Einstein called his worst mistake, scientists are now depending on to help explain the universe.

In 1917, Albert Einstein inserted a term called the cosmological constant into his theory of general relativity to force the equations to predict a stationary universe in keeping with physicists' thinking at the time. When it became clear that the universe wasn't actually static, but was expanding instead, Einstein

abandoned the constant, calling it the '"biggest blunder" of his life.

But lately scientists have revived Einstein's cosmological constant (denoted by the Greek capital letter lambda) to explain a mysterious force called dark energy that seems to be counteracting gravity ? causing the universe to expand at an accelerating pace.

A new study confirms that the cosmological constant is the best fit for dark energy, and offers the most precise and accurate estimate yet of its value, researchers said. The finding comes from a measurement of the universe's geometry that suggests our universe is flat, rather than spherical or curved.

Physicists Christian Marinoni and Adeline Buzzi of the Universite de Provence in France found a new way to test the dark energy model that is completely independent of previous studies. Their method relies on distant observations of pairs of galaxies to measure the curvature of space.

Marinoni and Buzzi set out to calculate the contents of the universe ? i.e. how much mass and energy, including dark energy, it holds ? by measuring its shape.

The geometry of space-time can distort structures within it. The researchers studied observations of pairs of distant galaxies orbiting each other for evidence of this distortion, and used the magnitude of the distortion as a way to trace the shape of space-time.

To discover how much the galaxy pairs' shapes were being distorted, the researchers

measured how much each galaxy's light was red-shifted ? that is, budged toward the red end of the visual spectrum by a process called the Doppler shift, which affects moving light or sound waves.

The redshift measurements offered a way to plot the orientation and position of the orbiting pairs of galaxies. The result of these calculations pointed toward a flat universe.

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But lately scientists have revived Einstein's cosmological constant (denoted by the Greek capital letter lambda) to explain a mysterious force called dark energy that seems to be counteracting gravity ? causing the universe to expand at an accelerating pace.

That part sticks out to me for some reason. Don't we already have a rule

stating that for every action there is an opposite and equal reaction?

By some guy named Newton, or something?

The reason it stands out to me is that we're still having trouble

figuring out what gravity is, exactly. Yet now we're focused on

figuring out what could be the Negative to gravity's Positive.

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Yes, the universe is flat. :rolleyes: Sometimes I wonder whether these people ever actually look around, or whether they make these statements based solely on a formula they've been working on for the last few months; ergo it must be true.

Dark matter is a theory. In order to prove it, assumptions have to made and then jerry-rigged into existing theories and shuffled about until it works.

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Yes, the universe is flat. :rolleyes: Sometimes I wonder whether these people ever actually look around, or whether they make these statements based solely on a formula they've been working on for the last few months; ergo it must be true.

Do you even know wtf it is you're arguing against? Expansion of space is explained by general relativity: Assuming the cosmological principle in space (homogeneity and isotropy in the spatial distribution of matter) one arrives to a solution of Einstein equations in which space can expand or contract. Observations tell us space expands. The validity of this description is given by the validity of the assumptions used for its derivation: In a scale where the distribution of matter is not homogeneous and isotropic, space must not expand (it may, however). Observations tell us that the present universe is homogeneous and isotropic as a whole at scales greater than 100 Mpc (326 million light years). What do we mean when we say the universe is flat? Well, in short, we mean that the space can be described by normal Euclidean geometry; for example, the angles of a triangle add up to 180 degrees. In fact, the latter is exactly what we usually use in our attempts to determine flatness. One could actually go out and perform such an experiment by constructing a giant triangle (with, say, laser beams shooting from one mountain to another) and measure the angles of this giant triangle. If, within the uncertainties, the angles added up to 180 degrees, one would conclude that the space in that region was approximately flat. Of course, we know now that the space near the earth's surface is very well approximated as flat, but there was no way for the ancients to be sure of this.

Likewise, without a direct measurement, there's no way that we can be sure whether or not the space in the observable universe is flat. This kind of thing is very difficult to do locally because we only expect the universe's curvature to be noticable on large scales (that is, at high redshift). It turns out the most effective method is to analyze the anisotropies in the cosmic microwave background (CMB), a last-scattering "surface" that was formed at around z ~ 1100. By looking at the length scale on which the CMB is most anisotropic, we can determine very precisely the flatness of the universe. Using WMAP, we were able to determine that the universe was flat to very high precision:

Omega=1.02+/-0.02

Where Omega being 1, equates to a flat universe. the average density of the universe and v=HoD is Hubble's constant. This is an elegant description of how mass curves space. That is, general relativity tells us that not only can we measure the geometry of space itself, but we can also infer it's geometry by measuring how much mass and energy occupy it. This should be kept in mind when one considers that the total energy density of the universe has been measured to correspond approximately to that needed to flatten the universe. In other words, the pictures are consistent -- the geometry is flat and the contents are sufficient to flatten it.

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Yes, the universe is flat. :rolleyes:

It's more complicated than that.

We live (arguably) in a 3D world. Well we do have 3 dimensions to say the least.

The Universe, even if it's 3D looks like a piece of paper. It IS flat. But it's more complicated than that, because as you say, it doesn't make that much sense...

What I think is, since we live in a 3D world, it would be cognitively impossible for us to know what the fourth dimension looks. And that's more suitable to describe the Universe.

Let's say you live in a 2D world. Try to explain to your 2D friend what the third dimension is. It is absolutely impossible. You do not have the ressources in the world you are to describe what the third dimension is. Even if you draw a flattened 3D drawing on a 2D sheet, the friend will simply not understand what you mean because it does not have the capacity to image what it is for a surface to be extruded.

Anyways, just a thought. Do what you want with it :p

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Do you even know wtf it is you're arguing against?

Firstly, not arguing, just trying to understand. I've read your post twice and I'll be honest, it's way over my head. But thanks for trying to elucidate anyway.

It's more complicated than that....

Thank you as well.

At the risk of sounding ignorant, so in this context "flat" doesn't actually mean flat at all (as in two dimensions), but it is the way in which this theory describes the universe, through geometry?

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At the risk of sounding ignorant, so in this context "flat" doesn't actually mean flat at all (as in two dimensions), but it is the way in which this theory describes the universe, through geometry?

lets just put it this way

'straight' means a line , 1 dimensional... as in, a straight line

when you take that to 2 dimensions, its 'flat' , like a flat surface

but what do you call it when you take that to 3 dimensions? there is no word for it... so we reuse 'flat'

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Firstly, not arguing, just trying to understand. I've read your post twice and I'll be honest, it's way over my head. But thanks for trying to elucidate anyway.

Thank you as well.

At the risk of sounding ignorant, so in this context "flat" doesn't actually mean flat at all (as in two dimensions), but it is the way in which this theory describes the universe, through geometry?

You got it. If you dig in wikipedia about "space-time" you can understand a little bit more about the subject, but as much as you can read (I've followed a whole astrophysics class at college), you'll still be ignorant (like me).

The space-time is a combination of gravity and the 3 dimensions flattened, where the effect of gravity represents ... let's say, a heavy rock on your floating sheet of paper that the Universe is. It curves the 2D sheet.

One of Einstein's theory for instance, says that the moon around the Earth actually goes in straight line, but since the Earth's weight distorts the space-time sheet, the moon actually falls a few millimeters towards us every second. In your world, it doesn't change a thing to say that the moon revolves around Earth and has an oval-shaped trajectory, but in astrophysics it's a major step forward.

AS complicated as these things can be, I always found them interesting :) I wish I could follow another class in my branch, but being an engineer in a factory, I don't think it's necessary, really :(

lets just put it this way

'straight' means a line , 1 dimensional... as in, a straight line

when you take that to 2 dimensions, its 'flat' , like a flat surface

but what do you call it when you take that to 3 dimensions? there is no word for it... so we reuse 'flat'

I'm not sure to understand what you mean... in our world, we DO have words to describe 3D stuff. In a 2D world we wouldn't.

I think it's more because when you're far far far far away from the Universe, it does seem flat. But when you're inside, it's very easy to see that it's in 3D. Like a sheet of paper for instance. It has two dimensions, but it also has a thickness. So no matter how flat a sheet can be, there’s a third dimension. But you notice it when you get very close to it. As a human person, you simplify by saying it’s 2D

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Let's just say that the universe is relatively flat. Of course it is a 3D object but, from a distance, it would appear thin and "flattish" compared to a truly spherical design.

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I'll make it even easier. The universe doesn't exist at all. It appears to be infinite as energy at the speed of light becomes infinate mass. We are just electrons etc that have imagined we are human & alive. That's why there is fractal geometry, the more they look inside atoms they find yet smaller infinte structures, quarks etc, etc. The new fangle hedron collider will find even smaller particles. Infinite mass is never ending, as we invent new tools to look closer the deeper they can look. It will never end, just like a fractal never ends but just repeats the same geometry for ever.

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I'm not sure to understand what you mean... in our world, we DO have words to describe 3D stuff. In a 2D world we wouldn't.

I think it's more because when you're far far far far away from the Universe, it does seem flat. But when you're inside, it's very easy to see that it's in 3D. Like a sheet of paper for instance. It has two dimensions, but it also has a thickness. So no matter how flat a sheet can be, there’s a third dimension. But you notice it when you get very close to it. As a human person, you simplify by saying it’s 2D

just like you are saying that a sheet of paper has a third dimension in thickness, i was simplifying it by saying it's 2d ... basically, a piece of string has a diameter too, but thats not what we are talking about... its the shape of the string and the piece of paper, and what they are representing, which matters...

if you were to use the string to measure distance, you'd hold it tight so it keeps straight... if you allow it to sag or kink, you'd get a wrong measurement which is greater than the actual distance...

and if you were to stick 2 pieces of clay on the piece of paper, if you hold the pieces of paper flat, the distance between the clay pieces 'on paper' will be equal to the real world distance (i.e. draw a straight line between the 2 pieces of clay), but if you fold the paper between the pieces of clay, the 'on paper' distance will be greater than the real world distance (the line you just drew is still the same length)

but what happens if its not 1 dimension (the string) or 2 dimensions (the piece of paper) , but 3 dimensions? if there are these distortions of space, the distance we measure will be more than the 'real world' distance, even though it is already the real world...hmm not sure if that sounds right....but anyway

and about the words to describe 3d stuff... if 'straight' is used for 1d , and the equivalent word for 2d is 'flat' , what is the equivalent word for 3d?

just like we can have a 'bend' in a one dimensional concept such as a road or a piece of string, and we can have a 'fold' in a 2 dimensional concept like a piece of paper, what word do we have which is equivalent for a 3 dimensional concept?

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