Even wondering about a mix of tired light and expansion. Also a group in India wondering about changes in gravity calculations. Afraid I lost the link but suggests a mod to Einstein's ideas that I assume would still fit where we can measure them.
Last time I saw a discussion about it more of physicist asked if we could look at changes in light over distance, wondering about LIGO, longest beam we have. Far far short of astro distances. Reflected sun light off the moon has shown one effect of gravity. Still pretty short and effects as expected.
Light though. Energy produces it, It exerts a force on objects and it's energy level is proportional to wavelength. It just goes on and on. The only thing that reduces it's energy is the expansion of the universe.
Modern observation relates to the past 100 years Not long at all in astro terms where process take rather a lot longer.
The energy of a photon of light is directly proportional to its frequency according to E = hf.
When light travels though a medium, it is absorbed and re-emitted by atoms. The time delay that this process involves makes the light appear to move more slowly in an optically transparent medium than in a vacuum.
Perhaps the intergalactic medium is responsible for slowing down the light from distant galaxy clusters, making them look further away than expected?
When light travels though a medium, it is absorbed and re-emitted by atoms. The time delay that this process involves makes the light appear to move more slowly in an optically transparent medium than in a vacuum.
Perhaps the intergalactic medium is responsible for slowing down the light from distant galaxy clusters, making them look further away than expected?
I've read about this but IIRC its also been debunked. Over long distances (BLY), a photon will encounter the intergalactic medium of one or two hydrogen atoms per m^3 so I suppose in theory it could appear to be getting red shifted. But then again, some photons may never encounter matter on their journey, so why don't we detect those, or are they such a small fraction of the measured incidence they are undetectable?
Yeah, I've been trying to say that first sentence. Actually I have been saying it, but I've not seen a sign of being understood.
Print material on the recent JWST observations: https://cosmosmagazine.com/space/astrophysics/universe-27-billion-years-old/
Could the Universe be twice as old as we currently think?
"...experts warn us to be cautious: “Extraordinary claims require extraordinary evidence,” says one cosmologist."
The new JWST observations have revealed mature galaxies at a time when the universe was relatively young. Their existence challenges our current understanding of how galaxies form and evolve over cosmic time.
Tired light, physical constants that change over time - each is simply a hypothesis trying to explain these new observations.
"A much simpler explanation for the existence of these galaxies may just be that we don’t fully understand galactic evolution in the early universe."
Could the Universe be twice as old as we currently think?
"...experts warn us to be cautious: “Extraordinary claims require extraordinary evidence,” says one cosmologist."
The new JWST observations have revealed mature galaxies at a time when the universe was relatively young. Their existence challenges our current understanding of how galaxies form and evolve over cosmic time.
Tired light, physical constants that change over time - each is simply a hypothesis trying to explain these new observations.
"A much simpler explanation for the existence of these galaxies may just be that we don’t fully understand galactic evolution in the early universe."
It has to be a good question to ask which is probably why the subject crops up now and again, Proving one way or the other - a bit tricky????
😉 Light sails
https://en.wikipedia.org/wiki/IKAROS
I mentioned solar sailing in posts #57 and #59.
The fact that photons have momentum provides a different way to travel through space.
NASA has cancelled its Solar Cruiser mission which was to test a solar sail the area of more than six tennis courts in an artificial orbit between the Earth and Sun.
You may be referring to the mysterious gravity hole found in the Indian ocean.
Here's the latest news:
https://www.forbes.com/sites/simone...le-in-the-indian-ocean-and-how-it-was-formed/
Known as the Indian Ocean Geoid Low (IOGL), the huge low density gravity region is thought to have been caused by plumes of magma in the Earth's mantle around 20 million years ago.
https://en.wikipedia.org/wiki/Mantle_plume
Rather early on with the current post count - read all - I doubt if many do,
No it related to the dark energy question. One web page, brief and not much detail. My firefox history doesn't always catch pages I visit. Probably relates to too many open tabs and windows.
I'll expand a little on the concept of the light sail, a means of space propulsion that relies on the fact that photons carry momentum.
A solar sail is a surface that’s attached to lightweight unmanned spacecraft. The sail is designed to reflect incoming photons from the Sun. In doing so, the momenta of the photons is transferred to the sail. This provides a force which pushes the sail, and hence the spacecraft it’s attached to, away from the Sun.
AjohnL has provided a link to IKAROS, one such unmanned spacecraft: https://en.wikipedia.org/wiki/IKAROS
The spaceprobe was last heard from in 2015 when about 130 million kilometres from the Sun.
A solar sail is a surface that’s attached to lightweight unmanned spacecraft. The sail is designed to reflect incoming photons from the Sun. In doing so, the momenta of the photons is transferred to the sail. This provides a force which pushes the sail, and hence the spacecraft it’s attached to, away from the Sun.
AjohnL has provided a link to IKAROS, one such unmanned spacecraft: https://en.wikipedia.org/wiki/IKAROS
The spaceprobe was last heard from in 2015 when about 130 million kilometres from the Sun.
A question that is hoped to be answered by the Vera C. Rubin Observatory currently being erected in Chile.
When completed, the world's largest digital camera will embark on a ten year mission to survey the structure of the Universe.
This is another "interesting" area
https://en.wikipedia.org/wiki/Superluminal_motion
Something I read about, text book I bought new long ago. I wondered if it had been sorted but after reading the above not sure,
More here
http://spiff.rit.edu/classes/phys200/lectures/superlum/superlum.html
https://en.wikipedia.org/wiki/Superluminal_motion
Something I read about, text book I bought new long ago. I wondered if it had been sorted but after reading the above not sure,
More here
http://spiff.rit.edu/classes/phys200/lectures/superlum/superlum.html
Superluminal motion or more accurately apparent superluminal motion is an illusion.
If a jet of hot gas is moving towards us at close to the speed of light, the light that is travelling towards us is coming from a place much closer than we think it is and arrives much sooner than we expect it to.
If a jet of hot gas is moving towards us at close to the speed of light, the light that is travelling towards us is coming from a place much closer than we think it is and arrives much sooner than we expect it to.
There are many Mathematical Jokes. This, of course, is the funniest! 😀
Me and John Conway have never published a mathematical paper together:
We had fundamental disagreements. He made it 196,883. I got 196,884.
My reasoning:
https://en.wikipedia.org/wiki/J-invariant
But certainly not 42! 🙂
Me and John Conway have never published a mathematical paper together:
We had fundamental disagreements. He made it 196,883. I got 196,884.
My reasoning:
https://en.wikipedia.org/wiki/J-invariant
But certainly not 42! 🙂
To use a mathematical term, your post appears to have taken us off on a tangent!
Perhaps with the j-invariant you are throwing us an elliptical curve ball? 😀
Talking about mathematics jokes:
"You have dialed an imaginary number, please rotate your handset ninety degrees and try again."
"Einstein originally introduced the constant in 1917[2] to counterbalance the effect of gravity and achieve a static universe, a notion that was the accepted view at the time. Einstein's cosmological constant was abandoned after Edwin Hubble's confirmation that the universe was expanding.[3] From the 1930s until the late 1990s, most physicists agreed with Einstein's choice of setting the cosmological constant to zero.[4] That changed with the discovery in 1998 that the expansion of the universe is accelerating, implying that the cosmological constant may have a positive value.[5]"
https://en.wikipedia.org/wiki/Cosmological_constant
Even Wikipedia can not fool around the gimmick math;-)
If mathematicians do not notice that this mathematics is arbitrary, must be;-)
... because it does not describe the observations but arbitrary interpretations...-)
https://en.wikipedia.org/wiki/Cosmological_constant
Even Wikipedia can not fool around the gimmick math;-)
If mathematicians do not notice that this mathematics is arbitrary, must be;-)
... because it does not describe the observations but arbitrary interpretations...-)
Special Relativity (which is about Spacetime and all that clock and measuring sticks stuff and mass increasing with velocity) is so evidently right that I don't know why anyone would try and debunk it.
The Large Hadron Collider would need a redesign if it were wrong. Magnetism is a Special Relativity effect.
General Relativity is the best theory we have for Gravity. It is mathematically extremely high level, but seems to work to exquisite precision. I don't understand the Cosmological Constant bit, but have seen the appropriate 4 element Tensor in Sean Carroll's book, and it seems to make sense as maths. All this Dark Energy, Dark Matter and Expanding Universe stuff is extremely mind-boggling. As is Special Relativity and Quantum Mechanics.
Whether you like it or not, we live in a very strange Universe! I am looking forward to Sean Carroll's next two volumes. Quanta and Fields should clarify what a Gravitational Field is, and why it is different from,say, electromagnetism. Complexity and Emergence may not be quite up my street, but must be important.
The Large Hadron Collider would need a redesign if it were wrong. Magnetism is a Special Relativity effect.
General Relativity is the best theory we have for Gravity. It is mathematically extremely high level, but seems to work to exquisite precision. I don't understand the Cosmological Constant bit, but have seen the appropriate 4 element Tensor in Sean Carroll's book, and it seems to make sense as maths. All this Dark Energy, Dark Matter and Expanding Universe stuff is extremely mind-boggling. As is Special Relativity and Quantum Mechanics.
Whether you like it or not, we live in a very strange Universe! I am looking forward to Sean Carroll's next two volumes. Quanta and Fields should clarify what a Gravitational Field is, and why it is different from,say, electromagnetism. Complexity and Emergence may not be quite up my street, but must be important.