Things that make you go "hmmm"?

Caroljeen

Well-known member

Mature galaxies from the dawn of time​

"We expected only to find tiny, young, baby galaxies at this point in time, but we've discovered galaxies as mature as our own in what was previously understood to be the dawn of the universe," Leja added.

 

Mature galaxies from the dawn of time​

"We expected only to find tiny, young, baby galaxies at this point in time, but we've discovered galaxies as mature as our own in what was previously understood to be the dawn of the universe," Leja added.


Sabine Hossenfelder talked briefly about this interesting discovery that came out last summer and the analysis was published in Nature: (Timestamp: ~ 3:31 - 5:47). What's even more curious is that Modified Newtonian Dynamics predicted these larger galaxies before their discovery, thereby falsifying the lambda cold-dark-matter standard model of cosmology.



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So does this mean Dark Matter is wrong and MoND is right? Or are there some things Dark matter gets right and MoND gets wrong and we need a third theory to bridge the two?
 
I just read this morning that a researcher was able to make light slow down to 17 mph and stop completely.

 
So does this mean Dark Matter is wrong and MoND is right? Or are there some things Dark matter gets right and MoND gets wrong and we need a third theory to bridge the two?

You've seen the simplified illustrations of the model as shown below:

Lambda_CDM Model_NASA.jpg


The Lambda-CDM model where lambda is the cosmological constant and CDM is Cold, Dark Matter is supported by observational evidence; so it is a good physical non-relativistic model.

- The universe is expanding
- Spacetime is flat, not curved
- independent measurements confirm its predictions

These observations (measurements) include the CMB temperature, Cosmic neutrino background, predictions about Nucleosynthesis, and the Universe's acceleration

In the MOND model, mass is treated not as an inherent characteristic of matter, but as an inertial response of matter instead. Clearly, more exploration is needed since a portion of its predictions was found to be correct to date.

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NASA
 
I just read this morning that a researcher was able to make light slow down to 17 mph and stop completely.


I remember reading about ^this^ not too long ago. Here is what one of the physicists has to say:


It's cool - literally.

( gotta love that laboratory! )

I'm betting that Harvard engineers have used the results to begin a new R&D effort here for quantum computing.


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Worth remembering that the speed of light is constant in a vacuum. It slows down by about a thirds when travelling through glass. That is not to say this is not an incredible achievement, but it is not breaking the laws of science as we know them.

I'm betting that Harvard engineers have used the results to begin a new R&D effort here for quantum computing..
I wonder how practical it will be if it is running at 0.000 000 001 K.
 
Worth remembering that the speed of light is constant in a vacuum. It slows down by about a thirds when travelling through glass. That is not to say this is not an incredible achievement, but it is not breaking the laws of science as we know them.


I wonder how practical it will be if it is running at 0.000 000 001 K.
Thank you, this is helpful context! :)
 
I remember reading about ^this^ not too long ago. Here is what one of the physicists has to say:


It's cool - literally.

( gotta love that laboratory! )

I'm betting that Harvard engineers have used the results to begin a new R&D effort here for quantum computing.


_______ :coffee:

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The physics:

In this set-up a Bose-Einstein Condensate of gaseous Sodium* in a vacuum chamber was irradiated using perpendicularly aligned tunable lasers to take advantage of fine-structure energy states within the lower 3s energy ground state shown in the energy level diagram below.

Figure 7_22 Tipler .jpg

Initially, all of the sodium atoms in this configuration have their spins aligned with two 3s hyperfine ground states separated by only ~ 3.5 * 10^-6 eV. When the leading-edge of the probe laser beam enters the ultra-cold, ground-state atomic cloud with another coupling beam perpendicular to the probe beam within the cloud, both the beams shift the sodium atoms into a quantum superposition of the hyperfine states where every atom exhibits --both-- of the 3s energy states simultaneously instead of pumping up the Sodium atoms to the 3p level. This phenomena is due to quantum interference provided by the laser beams causing the index of refraction to cancel over a very narrow frequency and this effectively compresses the pulse to less than the length of the atomic cloud.

When the coupling beam is turned off, the pulse is turned off, leaving the superposition of energy states intact within the atomic cloud in a manner similar to a hologram of the spins imprinted within the atoms. When the coupling laser is turned back on, the cloud is no longer opaque and the beam continues on its original path at 3*10^8 m/s.


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* Figure 7-22 is from Tipler, "Modern Physics", W.H. Freeman and Company, NY, Chapter 7, sixth edition
 
A possible explanation maybe time passed slower near the beginning? We know passage of time is relative. In the movie Interstellar, 1 hour on Miller's planet near the black hole Gargantua is 7 years on earth. Say you're on Miller's planet and had a Zoom call with someone on earth. An hour later you do another Zoom and that person could have aged noticeably.
 
A possible explanation maybe time passed slower near the beginning? We know passage of time is relative. In the movie Interstellar, 1 hour on Miller's planet near the black hole Gargantua is 7 years on earth. Say you're on Miller's planet and had a Zoom call with someone on earth. An hour later you do another Zoom and that person could have aged noticeably.

Hi vbj -

Are you familiar with the cosmological principle where at any given time and at very, very large scales, the universe is treated as an essentially homogeneous and isotropic system? This principle has been validated through deep observations of our universe as shown in the image below*:
Large Scale Image of the Universe Schmidt Telescope.jpg

As one can see, the distribution of galaxies appears to be statistically homogeneous and isotropic at very, very large scales.

When observing a distant object like the distant galaxies in the OP and then mathematically projecting a spherical shell with a radius r at any given time from the origin to the galaxy, the cosmological principle requires that all of the shells expand in an identical fashion within spacetime.

- Here is a diagram showing the concept:

Cosmological Principle Expanding Shells in Universe.jpg

In an expanding universe the positions of two points that are recorded at the same time supply meaning to the word separation. This is where the shell's comoving coordinate supplies meaning in relativistic cosmology for an isotropic homogeneous universe. The expansion of spacetime affects all geometric parameters of the universe in an identical fashion.

Relativistic effects occur when an object is close to an event horizon near a powerful gravitational well such as a black hole, or when an object is moving very near the speed of light. When objects are near a black hole their shapes change and gravity literally shreds their existence apart. It is hear where time begins to lose meaning.

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* Reference: Tipler, "Modern Physics fifth ed.", W. H. Freeman and Company, 2008, P. 662 and P. 665
 
Hi vbj -

Are you familiar with the cosmological principle where at any given time and at very, very large scales, the universe is treated as an essentially homogeneous and isotropic system? This principle has been validated through deep observations of our universe as shown in the image below*:
View attachment 3973

As one can see, the distribution of galaxies appears to be statistically homogeneous and isotropic at very, very large scales.

When observing a distant object like the distant galaxies in the OP and then mathematically projecting a spherical shell with a radius r at any given time from the origin to the galaxy, the cosmological principle requires that all of the shells expand in an identical fashion within spacetime.

- Here is a diagram showing the concept:

View attachment 3974

In an expanding universe the positions of two points that are recorded at the same time supply meaning to the word separation. This is where the shell's comoving coordinate supplies meaning in relativistic cosmology for an isotropic homogeneous universe. The expansion of spacetime affects all geometric parameters of the universe in an identical fashion.

Relativistic effects occur when an object is close to an event horizon near a powerful gravitational well such as a black hole, or when an object is moving very near the speed of light. When objects are near a black hole their shapes change and gravity literally shreds their existence apart. It is hear where time begins to lose meaning.

________________

* Reference: Tipler, "Modern Physics fifth ed.", W. H. Freeman and Company, 2008, P. 662 and P. 665
Thanks, I'm not familiar with that concept but interesting.
 
Thanks, I'm not familiar with that concept but interesting.

Astrophysics is interesting.

Here is what happens to a star as time becomes meaningless near the "edge" (event horizon) of a black hole:



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