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Nov 18, 2019
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Dr. Joe,

The reason that I repeatedly raise the issue about Einstein's relativity here is that I am confident that Einstein's relativity is wrong but the mainstream physicists and journal editors refuse to accept the fact and are rejecting all anti-relativity papers unconditionally without discussions and debating. If Einstein's relativity is indeed wrong, then all modern physics theories are wrong and the delay to confirm it is causing huge amount of waste of money and efforts everyday in the world. Therefore, this is an extremely important issue. I hope that you will invite more influential physicists to join our discussions here to resolve the issue.

Your support will be greatly appreciated.

Sincerely,
Xinhang Shen
 
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DrJoePesce

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Hello Dear Astro Enthusiasts. I want to bring you an interesting research result, hot off the presses, about one of my favorite topics - black holes!

Caltech researchers discovered a binary supermassive black hole in a distant object known as a blazar. These are active galaxies with the jet of material squirted out from near the black hole pointed nearly directly at us. The finding, presented here:

www.caltech.edu/about/news/colossal-black-holes-locked-in-dance-at-heart-of-galaxy

confirms only the second known binary supermassive black hole. It is based on 45 years of observations, with contributions by NSF's National Radio Astronomy Observatory (NRAO)!! We suspect mainy supermassive black holes have companions, but these are difficult observations to make.

These black holes will eventually merge, producing gravitational waves, though not the type we can detect with the NSF's Laser Interferometer Gravitational Wave Observatory (LIGO).

More info about black holes is here:

www.nsf.gov/blackholes
 
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DrJoePesce

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Given Earth’s/Sun’s motions, what reference frame determines a redshift value?
Hello Helio! The reference frame for redshift values is just what we measure on the Earth. We do move, of course, but all the galaxies are moving away us (as viewed by us), and so measuring the motion away from us (the so-called redshift) is little affected by our motion. Redshift is linked to the universal expansion which is on a MUCH larger scale than our local motions. And the light travel time from distant objects is independent of our local motion. We do know our local motions quite accurately so can definitely correct for these if necessary.
 
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These black holes will eventually merge, producing gravitational waves, though not the type we can detect with the NSF's Laser Interferometer Gravitational Wave Observatory (LIGO).
That's surprising. Given their "colosal" mass, and that wave amplitude is only a linear reduction with distance, what would make LIGO ineffective?
 
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Hello Helio! The reference frame for redshift values is just what we measure on the Earth. We do move, of course, but all the galaxies are moving away us (as viewed by us), and so measuring the motion away from us (the so-called redshift) is little affected by our motion.
Yes, thanks.

I should have crunched some numbers, if only to help me get my head around redshift values.

Crunch, crunch... it looks like that even with our ~1000 kps boost with our MW rush to the Atractor, plus the 220 kps bump if radial with our galactic motion, plus 30 kps if aligned with our solar orbital motion, z is only 0.0048. Not enough to upset any galactic apple cart. :)

We do know our local motions quite accurately so can definitely correct for these if necessary.
Yes, which seems likely necessary for MW objects. The Centauri system, for instance, has a radial velocity less than our solar orbital velocity (-21 kps and 30 kps, respectively).
 
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DrJoePesce

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That's surprising. Given their "colosal" mass, and that wave amplitude is only a linear reduction with distance, what would make LIGO ineffective?
Helio - great job on crunching the numbers on the other thread!

As for the gravitational waves:

Gravitational wave frequencies are inversely proportional to mass of the object emitting the waves: Mass goes up frequency goes down.

LIGO, and other, similar, ground-based gravitational-wave observatories are designed for high-frequency gravitation waves: ~10-2 to 10,000 Hertz. The sources for these waves are the merging stellar-sized black holes and neutrons stars we are hearing about.

Merging supermassive black holes have gravitational waves with frequencies in the 10-10 to 10-2 Hertz, and some of these (the higher-frequency ones) will be detectable by the LISA (European Space Agency/NASA) satellite mission in the future.
 
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Merging supermassive black holes have gravitational waves with frequencies in the 10-10 to 10-2 Hertz, and some of these (the higher-frequency ones) will be detectable by the LISA (European Space Agency/NASA) satellite mission in the future.
Thanks! You gotta love the irony - those colosal black holes are too big to "see"! :)
 
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Feb 7, 2022
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Hi marvel! The universe is the entity that includes us and everything, as a whole. Space is the emptiness in which astronomical objects (and us!) are found. From a formal definition perspective, space is contained within the universe. Does this help?
Ok that is cleared. Is there a general term used to describe what encapsulates the universe in the case of multiple universes or like what name is given to the region containing our universe and possibly other universe?
 
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Sep 15, 2021
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Ok that is cleared. Is there a general term used to describe what encapsulates the universe in the case of multiple universes or like what name is given to the region containing our universe and possibly other universe?
The term "Universe", by its own definition, embraces all that exists, so that it allows no plural, and its initial letter must always be a capital letter. If it is somehow segmented and its segments are completely isolated from one another then they must be called something else, never "universes" or "parallel universes". Call them "hermetic pods", "no-access islands", "stranded worlds", or whatever else you want, but don't use the Name of the One and Only Universe to allude to them.
 
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DrJoePesce

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The term "Universe", by its own definition, embraces all that exists, so that it allows no plural, and its initial letter must always be a capital letter. If it is somehow segmented and its segments are completely isolated from one another then they must be called something else, never "universes" or "parallel universes". Call them "hermetic pods", "no-access islands", "stranded worlds", or whatever else you want, but don't use the Name of the One and Only Universe to allude to them.
Thanks Starcrow. And, moreover, multiple "others" are only speculation (and science fiction) at the moment....
 
Hi Doc!

If you get a chance, please take a look at the bullet list (link below) that puts all the separate lines of objective evidence supporting the BBT. Too often some people hold the view that such an abundant amount of real hard-earned evidence exists for an overarching cosmological view. It's still amazing to me that we have such a remarkable model. The history behind it is also remarkable.

If you see any needed nits or important changes, please let me know. I tried to keep it simple since it's easy to Google these topics for in-depth knowledge behind them.

Big Bang Bullets
 
Mar 27, 2020
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Hi Asmelash gebremariam. I'm sorry, I don't understand your question.
Did you mean difference between astronomy and planetary science? They do overlap, for sure, with astronomy more focused on stars. galaxies and other objects at scale and planetary specifically looking at the rocky bodies of planets, asteroids, and comets. Interestingly, a lot of the tools to study them are the same (such as looking at light from those sources to determine their chemistry), but thanks to meteorites--and robotic explorers--we can study planetary fragments more directly, too.
 

DrJoePesce

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Hi Doc!

If you get a chance, please take a look at the bullet list (link below) that puts all the separate lines of objective evidence supporting the BBT. Too often some people hold the view that such an abundant amount of real hard-earned evidence exists for an overarching cosmological view. It's still amazing to me that we have such a remarkable model. The history behind it is also remarkable.

If you see any needed nits or important changes, please let me know. I tried to keep it simple since it's easy to Google these topics for in-depth knowledge behind them.

Big Bang Bullets
Hi Helio - Your list is extensive; I won't comment on whether it's complete (not because I don't think it is but because I don't know!). A couple of quick thoughts:

- Quasars in the past: yes, but not that the universe was (necessarily) more dynamic. Instead, I think, implying the universe was smaller and galaxy-galaxy interactions were more common (with the implications that galaxy-galaxy interactions drive the activity in the central regions of the galaxes, that is, feeding the supermassive black hole).

- Distant supernova: I'm assuming these are the observations leading to "dark energy". It's not "dilation" but rather that some supernova (around 1 billion light years away/ 1 billion years ago) are more distant than a uniform expansion rate implies. Hence dark energy, that is causing the expansion rate to accelerate.

- Olber's paradox: I don't know if I would include this as support for the BBT. What it does support is that the universe is not infinitely big (and old)

Note that some of these items will be tweaked as new observations are made. Some that come to mind are big spiral galaxies very early in the universe (the lack of which you take as evidence for the BBT) and very large black holes in the same period (bigger than we think possible in that period). Some examples: https://www.space.com/old-galaxy-in-early-universe-aless0731 https://www.space.com/oldest-spiral-galaxy-in-universe.

If these observations hold (and the Webb Telescope will help here), it is telling us that we need to learn more about the early universe, but probably not, necessarily, that the BBT is wrong.
 
- Quasars in the past: yes, but not that the universe was (necessarily) more dynamic. Instead, I think, implying the universe was smaller and galaxy-galaxy interactions were more common (with the implications that galaxy-galaxy interactions drive the activity in the central regions of the galaxes, that is, feeding the supermassive black hole).
Agreed. "Dynamic" isn't the best word to use. It is the no. of small gallaxies forming large ones, as you note, that needs the focus. I'll polish this bullet so it riffles better. ;)

- Distant supernova: I'm assuming these are the observations leading to "dark energy". It's not "dilation" but rather that some supernova (around 1 billion light years away/ 1 billion years ago) are more distant than a uniform expansion rate implies. Hence dark energy, that is causing the expansion rate to accelerate.
That aspect might make for a new bullet I hadn't considered since it fits within the BBT.

However, the time dilation arguement is different. The time dilation of SN some say is the best of all the arguments for expansion. I failed to convey the crux of the argument as it is a little more involved than average.

[for general consumption...] When we compare a nearby SN Type 1a to a very distant SN Type 1a, and if we were to assume they were identical in every respect, not only would we see greater redshift for the more distant SN but we would expect to see the peak light (also diminished due to reduced photon flux) take more time to decay. This "time dilation" is attributable to the much greater recessional speed from us. So, after a given no. of months, the distant SN will be much farther away taking the bright light longer to reach us, thus lasting longer than the closer SN.

This is important because redshift alone has been debateable from the start. Time dilation, however, seems very substantial in arguing expansion, including its rate. [Hubble never argued that redshift was due to expansion, contrary to a ton of claims otherwise. I suspect his personal time with deSitter at the Solvay conference (1928 IAU meeting in Holland) influenced him. DeSitter produced a solution to GR that demonstrated redshift for a Static Universe, but his model included no mass in the universe. :) Einstein's solution had mass but no redshift. Lemaitre was the first to offer both as a physics model (Friedman had presented a math model earlier, unknown to Lemaitre). Hubble did say, IIRC, that he wanted to leave theory to theorists, hence keeping his worthy claim as a great astronmer in tact. Recall some astronomers ventured into theory with some regrets. :)]

- Olber's paradox: I don't know if I would include this as support for the BBT. What it does support is that the universe is not infinitely big (and old)
Yes, but I think it negates some of the major counter theories (e.g. Steady State) that do argue infinite age and size, thus it still is an arugment that at least favors BBT. It isn't as strong as other bullets, admittedly, just worth mentioning, I think.

Note that some of these items will be tweaked as new observations are made. Some that come to mind are big spiral galaxies very early in the universe (the lack of which you take as evidence for the BBT) and very large black holes in the same period (bigger than we think possible in that period). Some examples: https://www.space.com/old-galaxy-in-early-universe-aless0731 https://www.space.com/oldest-spiral-galaxy-in-universe.
Any surprises, of course, will be welcome as this will add to the excitement inherent in astronomy. :)

Giant early galaxies, IMO, will still be seen as more oxymoronic than not. If their distribution is anything close to that of today then we certainly will have a problem. Is this a fair statement?

If these observations hold (and the Webb Telescope will help here), it is telling us that we need to learn more about the early universe, but probably not, necessarily, that the BBT is wrong.
Yes, Webb's unique access to those regions of the early universe should have a lot to say about BBT. Perhaps something will be seen that will help qualify some of the Inflation theories, as well.

Thanks for your comments!
 
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Feb 7, 2022
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The term "Universe", by its own definition, embraces all that exists, so that it allows no plural, and its initial letter must always be a capital letter. If it is somehow segmented and its segments are completely isolated from one another then they must be called something else, never "universes" or "parallel universes". Call them "hermetic pods", "no-access islands", "stranded worlds", or whatever else you want, but don't use the Name of the One and Only Universe to allude to them.
Ok
 

DrJoePesce

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I'm posting a question and response to a question I received in my person inbox from @atabti.

Dear Dr Joe -

Is it still the oldest known volcanic rock on Earth?

Also, is the rock older than the planet Earth?

Source : https://en.wikipedia.org/wiki/Erg_Chech_002

Thank you


Hello Akli - Thanks for the question. First off, this is outside my area of expertise, and I can't directly answer your specific question. But I can provide some insight, I hope:

The early solar system is fascinating, isn't it? Obviously of importance to us (since it is our history) and gaining importance as we detect forming (and formed) planetary systems around other stars.

Some meteorites are (or contain) among the earliest components of our newly formed solar system (or, indeed, the cloud from which our Sun and solar system formed). The particular meteorite you mention above is likely one of these.

I point you to another famous meteorite, long know to contain various amino acids and other components from the pre-solar gas cloud that went on to form our solar system. Components of it were recently dated to 7 billion years ago! See here: https://www.space.com/stardust-oldest-material-on-earth.html

Hope this helps!
 
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Apr 5, 2021
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Hi Joe,

If you could put Large Hydron Collider in space would it be possible to use it to send small object or a cubesat 1 molecule at time to our neighboring solar system 4 light years away, (Proxima Centauri I think) where it would be slowed by gravity and recollected. It would accelerate them to speed of light and then continuously transmit to the other star may be like StarTrek transporters. Is that technology also possible?

Thanks
 
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Nov 18, 2019
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Many thanks, Dr. Joe for answering so many questions here!

It has been a while since my last question. How is it going? Have you got someone to confirm how the clocks on the GPS satellites and clocks on the ground are synchronized?

>DrJoePesce said:
>Thanks for the follow-up XinhangShen. My understanding (maybe incorrect) is that the
>GPS satellites' clocks are synchronized. I don't think they are synchronized with the
>ground clocks. I'll see if I can get someone better versed in this subject to weigh in.
 
Hello Dr. Joe,

I, in case you haven't notice, gravitate to the more fun-like stuff that is abundant in astronomy. One of interest to me, partly due to my interest in astro history, is the Geocentric model within GR.

First, take a modified Tychonic model - where the Sun is the center of all the planets, except Earth, and they and the heavens revolve around the fixed Earth. [I'm not at all suggesting this as any real model, but there is a novelty to it that intrigues me.] The modified part is mainly using elliptical orbits and different orbital speeds, where Tycho and even Copernicus were stuck on perfect circular orbits and constant speeds.

Second - GR argues that any point can be taken as the center of the universe. [The fact that no point can be taken as an absolute is why GR does not argue the Earth is THE center.]

Third - The First will meet all observable requirements as our modern model. [I'm fairly sure.]

Fourth - To meet the Third premise, however, "fictious forces" would be required to provide cause and effect. These fictious forces are its downfall as they strain credulity.

Would the Fourth also be your view, or is there more to this? Is "fictious forces" the proper term?
 

DrJoePesce

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Many thanks, Dr. Joe for answering so many questions here!

It has been a while since my last question. How is it going? Have you got someone to confirm how the clocks on the GPS satellites and clocks on the ground are synchronized?

>DrJoePesce said:
>Thanks for the follow-up XinhangShen. My understanding (maybe incorrect) is that the
>GPS satellites' clocks are synchronized. I don't think they are synchronized with the
>ground clocks. I'll see if I can get someone better versed in this subject to weigh in.
Thanks for reaching out. As you know, I'm not an expert, but I believe the answer is that clocks on the satellites are not synchronized with the ground.

I have not yet ID'ed anyone to weigh-in on this, but am working on it. Maybe there is someone in the forum who could comment?
 
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DrJoePesce

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Mar 31, 2020
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Hi Joe,

If you could put Large Hydron Collider in space would it be possible to use it to send small object or a cubesat 1 molecule at time to our neighboring solar system 4 light years away, (Proxima Centauri I think) where it would be slowed by gravity and recollected. It would accelerate them to speed of light and then continuously transmit to the other star may be like StarTrek transporters. Is that technology also possible?

Thanks
Hi suneritz - Always good to hear these great, out-of-the box, ideas! And that's a novel use for an accelerator!

Apart from the fact that we can't break something into its constituent elements, let alone put it back together, we have a couple of inconvenient facts about physics. 1) The speed of light: Nothing with mass (so the molecules, or even sub-atomic particles if we could get to that level too) can travel faster than the speed of light in vacuum. We might be able to accelerate the particles to a fraction of the speed of light but not to the speed of light. It would still take a long time for travel. 2) Newton's laws - gravity could possibly slow the particles as they neared a target star, but it would likely not be sufficient, and they would just zoom by.

Since I don't want to end on a low note, here are some fun things related to your suggestion:

SpingLaunch: https://www.space.com/spinlaunch-first-test-flight-success

And lots of research into linear accelerators to launch payloads - mass drivers: https://en.wikipedia.org/wiki/Mass_driver
 

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