If every point in universe is a starting point of the universe does that mean universe is producing itself.
@cumbb We discussed the long-standing problem of the cosmological constant earlier in the thread.
The cosmological constant we refer to today is not the same as that first used by Einstein in order to balance gravity and ensure a Universe that was neither expanding nor contracting.
In modern cosmology, the cosmological constant, lambda, represents the inherent energy density of empty space which no longer just balances gravity , but overwhelms it, causing the Universe to expand.
However, the discovery that the Universe is expanding at an accelerating rate has made lambda problematic.
We require some form of additional energy throughout the Universe to explain its accelerating expansion. Dark energy is the cover-all term used for the various theories that could account for the accelerating expansion.
Unfortunately, the theoretical value of lambda differs from observation, being greater than the latter by some 120 orders of magnitude.
The cosmologists are not hiding anything here. They may have to consider adjusting our theories of gravity to account for the cosmological constant problem!
I freely adapted information from this article: https://physicsworld.com/a/a-new-generation-takes-on-the-cosmological-constant/
The cosmological constant we refer to today is not the same as that first used by Einstein in order to balance gravity and ensure a Universe that was neither expanding nor contracting.
In modern cosmology, the cosmological constant, lambda, represents the inherent energy density of empty space which no longer just balances gravity , but overwhelms it, causing the Universe to expand.
However, the discovery that the Universe is expanding at an accelerating rate has made lambda problematic.
We require some form of additional energy throughout the Universe to explain its accelerating expansion. Dark energy is the cover-all term used for the various theories that could account for the accelerating expansion.
Unfortunately, the theoretical value of lambda differs from observation, being greater than the latter by some 120 orders of magnitude.
The cosmologists are not hiding anything here. They may have to consider adjusting our theories of gravity to account for the cosmological constant problem!
I freely adapted information from this article: https://physicsworld.com/a/a-new-generation-takes-on-the-cosmological-constant/
Psyche was launched today - a NASA mission to study an asteroid with the same name - located in the main asteroid belt between Mars and Jupiter.
https://science.nasa.gov/mission/psyche/
The special thing about this asteroid is that it is composed more of metal than rock or ice. This indicates that Psyche may be a planetesimal.
Planetesimals are the building blocks of rocky planets and Psyche's composition may tell us more about how rocky planets form and about the composition of Earth's inaccessible core.
P.S. Science fiction fans should not confuse metal-rich asteroid Psyche with planet Metaluna. 😉
At Psyche we should find no monsters!
https://science.nasa.gov/mission/psyche/
The special thing about this asteroid is that it is composed more of metal than rock or ice. This indicates that Psyche may be a planetesimal.
Planetesimals are the building blocks of rocky planets and Psyche's composition may tell us more about how rocky planets form and about the composition of Earth's inaccessible core.
P.S. Science fiction fans should not confuse metal-rich asteroid Psyche with planet Metaluna. 😉
At Psyche we should find no monsters!
The rate of expansion is not same that everyplace in universe it's different for different spacetime value. A void will expand more then a place just besides a huge black hole. Although it's a small difference it's enough for dark energy to exist.
Theorist anyone.
Theorist anyone.
Surely this would have been accounted for though? In the Gaia survey I assume they are looking at really big structures where this stuff would be ‘easily’ reconciled with the overall findings.
Yes, the cosmic expansion I referred to earlier is occurring in the vast voids between galaxy clusters where gravity has little or no influence.
The X-ray study of distances to galaxy clusters revealed two regions in the Universe where clusters were potentially closer or farther away than expected.
This led to the suggestion that the rate of cosmic expansion in these two regions is correspondingly slower or faster than the rest of the Universe.
There is a recent theory that black holes are the source of dark energy. https://iopscience.iop.org/article/10.3847/2041-8213/acb704
The theory is called Cosmological Coupling and suggests that the gravitating mass of a black hole can increase with the expansion of the universe independently of accretion of matter or black hole mergers.
The authors claim that black holes "contribute cosmologically as vacuum energy" and propose that "stellar remnant black holes are the astrophysical origin of dark energy, explaining the onset of accelerating expansion".
Let's just say that the physics community is not wholly convinced!
The "really big structures" they looked at are the galaxy clusters - gravitationally bound collections of hundreds or thousands of galaxies.
The "gravitational tugs" between galactic clusters will be relatively small as we are talking about cluster separations comprising vast distances (voids).
So, I don't see this alternative explanation of the different rates of expansion as making any sense. As I say, I've found no more information.
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Here's my last word on the observations of possible different rates of cosmic expansion.
The following discussion of the galaxy cluster study states that there are several reasons to be cautious about the results.
https://www.universetoday.com/14560...expanding-at-the-same-rate-in-all-directions/
The actual research paper is certainly a lot more measured in its conclusion:
https://arxiv.org/abs/2004.03305
The following discussion of the galaxy cluster study states that there are several reasons to be cautious about the results.
https://www.universetoday.com/14560...expanding-at-the-same-rate-in-all-directions/
The actual research paper is certainly a lot more measured in its conclusion:
https://arxiv.org/abs/2004.03305
"Cosmic expansion" is NOT observed!
"Cosmic expansion" is an interpretation of observation and description.
"Cosmic expansion" is an interpretation of observation and description.
@cumbb, I am pleased to see your punctuation is improving. At last you end sentences with a stop or other more suitable punctuation.
Rather than ;-)
Well done! Perhaps space your two lines next time. Just a thought. Makes it easier to read.
Start off with a coincidental bit of fun. You recall I took this low resolution picture on Tuesday morning, 06.36 GMT 10 Oct 2023?
The most excellent and higher resolution Subaru Observatory in Hawaii had the same idea:
https://www.bbc.co.uk/news/av/world-us-canada-67082119
The Moon and Venus, for sure. Maybe Regulus in Leo too, but it is hard to tell with such erratic cloud cover:
I love being right!
I was really wanting to hark back to Conformal Cyclic Cosmology by Roger Penrose. A most interesting notion:
https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology
I find this geometrical interpretation of the Universe right up my street.
A nearby street in Ryde, IOW has the Orrery Cafe:
Outside is a skilled artistic representation of an angle-preserving Conformal Transformation. Straight lines map onto circles and circles map onto straight lines.
I thought I was looking at a mirror-ball, but having studied it from several angles, I was deeply confused. Happily a plaque nearby explained it is a painting on a sphere.
I still don't quite understand how it was done.
https://en.wikipedia.org/wiki/Conformal_geometry
There is still much to learn about Spacetime Geometry! 🙂
Rather than ;-)
Well done! Perhaps space your two lines next time. Just a thought. Makes it easier to read.
Start off with a coincidental bit of fun. You recall I took this low resolution picture on Tuesday morning, 06.36 GMT 10 Oct 2023?
The most excellent and higher resolution Subaru Observatory in Hawaii had the same idea:
https://www.bbc.co.uk/news/av/world-us-canada-67082119
The Moon and Venus, for sure. Maybe Regulus in Leo too, but it is hard to tell with such erratic cloud cover:
I love being right!
I was really wanting to hark back to Conformal Cyclic Cosmology by Roger Penrose. A most interesting notion:
https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology
I find this geometrical interpretation of the Universe right up my street.
A nearby street in Ryde, IOW has the Orrery Cafe:
Outside is a skilled artistic representation of an angle-preserving Conformal Transformation. Straight lines map onto circles and circles map onto straight lines.
I thought I was looking at a mirror-ball, but having studied it from several angles, I was deeply confused. Happily a plaque nearby explained it is a painting on a sphere.
I still don't quite understand how it was done.
https://en.wikipedia.org/wiki/Conformal_geometry
There is still much to learn about Spacetime Geometry! 🙂
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Simply speaking, a conformal transformation preserves angles between lines.
If we imagine a coordinate grid drawn on a flat elastic surface, the transformation stretches the elastic and in so doing, stretches the coordinate grid line spacing.
For a transformation to be conformal the angle between two lines drawn between two coordinate points on the grid must be the same after the transformation (a stretching of the elastic) as it was before.
https://www.quantumfieldtheory.info...g, stretches the coordinate grid line spacing.
The Mercator projection shown above is an example of a conformal transformation. https://en.wikipedia.org/wiki/Mercator_projection
If we imagine a coordinate grid drawn on a flat elastic surface, the transformation stretches the elastic and in so doing, stretches the coordinate grid line spacing.
For a transformation to be conformal the angle between two lines drawn between two coordinate points on the grid must be the same after the transformation (a stretching of the elastic) as it was before.
https://www.quantumfieldtheory.info...g, stretches the coordinate grid line spacing.
The Mercator projection shown above is an example of a conformal transformation. https://en.wikipedia.org/wiki/Mercator_projection
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A point Re. "The Expanding Universe" >
As galaxies slowly move apart, localized gravity within those galaxies still exists.
So, gravity still exists within an expanding universe.
(a hint of other things is when large stars go supernova inside of those galaxies)
As galaxies slowly move apart, localized gravity within those galaxies still exists.
So, gravity still exists within an expanding universe.
(a hint of other things is when large stars go supernova inside of those galaxies)
"Gravity still exists within an expanding universe."
There can be no argument with the above, but I would change your statement from "As galaxies slowly move apart..." to "As galaxy clusters slowly move apart..."
There can be no argument with the above, but I would change your statement from "As galaxies slowly move apart..." to "As galaxy clusters slowly move apart..."
To be exact, cosmic expansion is a large scale phenomenon that operates at the distance scales of galaxy superclusters.
A supercluster is a large group of smaller galaxy clusters. The large voids of space between superclusters means that they, unlike galaxy clusters, participate in cosmic expansion.
The Milky Way is part of the local galaxy group which comprises 54 galaxies. Here, the distances between the individual galaxies are relatively small, meaning that they are gravitationally bound together in such a way as to overcome cosmic expansion.
You will be aware that our nearest galactic neighbour, the Andromeda galaxy, far from expanding away from us, is actually moving closer to the Milky Way galaxy due to their mutual gravitational attraction. The two galaxies are expected to 'collide' in about 4.5 billion years time.
The attachment shows how the Andromeda galaxy would appear in the sky if the light from it was not so dim, reinforcing its close proximity to us.
Attachments
If this were indeed true, how do you explain the following based on E= mc^2 :-
If I take 1kg of fissile material, I can extract a large proportion of that energy in a tiny fraction of a second. Alternatively, I could use it with the relevant controls and extract the same amount of total energy from the 1 kg of fissile material over many years.
That being the case, how can time be an illusion if it is central to how we understand energy?
Time is intrinsic to our universe. It is not absolute, as our senses might suggest, but subject to relativity, which we can measure.
Our perception of time is somewhat illusory though. Although it is affected by time dilation due to relativity, we don't experience it that way. We can "experience" time dilation though, by measuring it.
Engineering calculations use time as a parameter in many models. If time was illusory, it would not have such a reliable relationship with our universe.
Our perception of time is somewhat illusory though. Although it is affected by time dilation due to relativity, we don't experience it that way. We can "experience" time dilation though, by measuring it.
Engineering calculations use time as a parameter in many models. If time was illusory, it would not have such a reliable relationship with our universe.
Who said time is an illusion? Why, none other than Albert Einstein himself!
"People like us who believe in physics know that the distinction between past, present, and future is only a stubbornly persistent illusion."
The time-ordering of events in spacetime is not agreed upon by all observers.
In the theory of relativity, events have an existence in spacetime beyond our local concept of past, present and future.
If we take the theory at face value, there is no sense in which the past has happened and the future is yet to happen.
"People like us who believe in physics know that the distinction between past, present, and future is only a stubbornly persistent illusion."
The time-ordering of events in spacetime is not agreed upon by all observers.
In the theory of relativity, events have an existence in spacetime beyond our local concept of past, present and future.
If we take the theory at face value, there is no sense in which the past has happened and the future is yet to happen.
The correct quote is:
“Time is an illusion. Lunchtime doubly so.”
- Douglas Adams, The Hitchhiker's Guide to the Galaxy
“Time is an illusion. Lunchtime doubly so.”
- Douglas Adams, The Hitchhiker's Guide to the Galaxy
I like your final paragraph 👍
I believe humans are missing a trick because we don’t acknowledge or even consider time as a force produced by energy. We think and say something takes place in time’ and not ‘when something takes place, one of the resultant forces produced is time’.
Perhaps therein lies the explanation for an expanding universe (dark energy) and dark matter (dark energy’s effects gravitationally bound).
Nothing Einstein or Maxwell formulated in their theories is violated. We just look at the universe through a slightly different lens.
See my previous posts on this outrageous hypothesis . . .
The thing is, if you're going to convince me that time is illusory, or an artificial construct, then you're going to have to rewrite a bunch of physics and engineering textbooks. You're going to have to show me how to design electronic filters, reliably and repeatedly, without using time domain parameters. You're going to have to explain how capacitors work without referring to time domain parameters.
Until then, I will remain unconvinced.
Until then, I will remain unconvinced.