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Jun 1, 2020
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We have a very adequate Big Bang Theory (more correctly, as you point out, Inflationary Model/Theory) which, however, is based on an insubstantial base where the division by zero (r) invalidates using the laws of physics.

I believe that the layman, looking at the suggested beginning – an infinitely small concept at infinite density and temperature, might find ‘bursting out of nothing rather less palatable than an honest admission that we do not know, and probably have no means of knowing, the ultimate precedent of inflation. On this occasion, might he not be correct?
Cat. This is the normal white font on black background, which no doubt, you were trying to achieve given the weird prior colors.

To answer your question that seems directed to others.... Yes, Dr. Joe, not surprisingly, has nailed it. The limits of science are not all that fuzzy. When your equations normally produce a clean result but, say close to t=0 events, they shoot to infinity, you know your wagon no longer has wheels. It's hard to push a wagon up a mountain that has no top. :)
 
Mar 31, 2022
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I have some questions that I need an urgent answer

(Where there is a place on Mars with -63 degrees (I would love if it would be with a picture
 

Catastrophe

"There never was a good war, or a bad peace."
"The density of dry ice increases with decreasing temperature and ranges between about 1.55 and 1.7 g/cm3 (97 and 106 lb/cu ft) below 195 K (−78 °C; −109 °F)." My emphasis.

Is that -63 Centigrade or Fahrenheit? As you see above, deg C is about 15 C Deg away.

Also, "A summer day on Mars may get up to 70 degrees F (20 degrees C) near the equator, but at night the temperature can plummet to about minus 100 degrees F (minus 73 degrees C)."

What is the temperature on Mars? | Space

Temp on Mars surface

For starters, Mars experiences an average surface temperature of about -55 °C (-67 °F), with temperatures at the pole reaching as low as a frigid -153 °C (-243.4 °F). Meanwhile, here on Earth the average surface temperature is 7.2 °C (45 °F), which is also due to a great deal of seasonal and geographic variability.9 Feb 2015

Your question makes no sense whatever without stating Centigrade or Fahrenheit.



Cat :)
 
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DrJoePesce

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Given that an object in a stable close orbit just outside the event horizon of a black hole will experience time dilation; then to a distant observer, will the orbital period appear to be slower than expected by purely Newtonian mechanics?
Hello Ray Gunn! Always a fascinating question: Newtonian dynamics would cause us to expect the object falling into the black hole to speed up as it gets near the event horizon. But, because of relativistic time dilation, to us (the outside observer), the object appears to slow down and then stop at the event horizon, never appearing to fall in. This is because the object is moving at the speed of light at the event horizon!
 

DrJoePesce

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Hi Dr Joe,

I have repeated questions and answers for clarity. Don’t worry, I have summarised it below. New in BOLD:

A multi-part question, if I may, about singularities.
1. My understanding is that, at t = 0, physical laws break down, due to division by zero. I also understand that beyond this zero point, by a minute interval, big bang theory is pretty solid, and this is reassuring. Am I OK so far?

Yes. But the division by zero is because the physical dimension, r, is zero (the universe is a singularity at time = 0).

1a. I am sorry, I should have cleared that my use of t = 0 here included an alternative scenario – namely the mid-point of a nexus (in that hypothetical scenario). Since I am open to thinking about (not necessarily supporting) such, I was making the point that the ‘OK part’ (BBT) can (according to this hypothesis) be considered irrespective of the precedent ‘singularity’, viz, separating the unknown beginning from the supported sequitur.


2. What is current official standpoint on such a (BB) singularity? Coming from (1), there are suggestions of infinite density, temperature et cetera. Am I correct in thinking that these infinite conditions are the result of singularity theory, and not essential prerequisites of the following BBT?


2. Well, I guess it’s not a requirement to have a singularity for a big bang event, but if you run the movie backwards, as it were, you end up with a singularity. (The same thing you have in a black hole, just with more mass.) We only have one universe, so the big bang model only operates in one place. And so, because of this, I would say that, yes, a singularity is a prerequisite. But to me, by calling it a prerequisite seems to indicate the model is operating somewhere else (another universe, for example), and, of course, we don’t know anything about other universes (or even if they exist). (By the way, the big bang theory is the vernacular name for the favored theory/model of the universe. It should be called the inflationary model/theory, for reasons we get to in your other post, below.)



2a. This starts by following from (1). I do not understand (mea culpa) how ‘running the movie backwards is a valid scientific process. The fact that you use a euphemism alerts me. When you have a jump like inflation, followed by a gradual curve, followed by increasing expansion, what sort of a backward projection do you make, and how do you justify it? Do you have enough data to make any such projection? If (not a straight line but) a ‘flattish’ parabola (or such) were fitted to the data, might not those incredibly small intervals like 10^-35 (10-35) become more ‘believable’ intervals? When we do not understand >95% of the observable universe, how can we begin to even think of laying down what the Universe was close to t = 0, whichever version we choose? What sort of scales do you use when you make the projection? Is this published somewhere I can access?

Please pardon my queries. I am a great fan of Korzybski (General Semantics) = “the map is not the territory”, et cetera. Probing is my second nature.

BTW I believe (if we are to uphold the viability of language) we have to ban words like universes, except in such a context as “Observable universes depend on the location of the observer” There is one ‘Universe’ in my book. Either we urgently need some new definitions or cosmology discussions are going to fail in short order.

Finally, my use of the word ‘prerequisites’, I believe, is quite justified. Suggesting ‘other universes’ is abhorrent in my book. I was merely asking whether the well attested BBT was inseparable from the (in my humble view) questionable (metaphysics, not science) model.

My question was “Coming from (1), there are suggestions of infinite density, temperature et cetera. Am I correct in thinking that these infinite conditions are the result of the singularity model, and not essential prerequisites of the following BBT?” In other words, Can we not (hypothetically) have BBT without some sort of (imho) fictional singularity?





3. I preface this question by stating that I am not looking for support of any particular outcome. I have serious reservations about some possible outcomes.
Is there any scientific reason why a singularity might not be replaced by a nexus, as in the cyclic scenario 'big crunch' or super black hole -> nexus -> big bang, omitting the singularity? I do accept that there are serious questions with cyclic models, particularly in relation to entropy and the 2ndLoTs.


3. I don’t know enough to know whether the singularity could be replaced by something else. I also don’t know why you might want to or need to replace it. Speaking of big crunches: Problems with these models aside, it is highly unlikely our universe will cycle like this: big bang, recollapse, big bang. There’s just not enough mass/density to allow that. Up to 20 years ago, it was thought to be highly unlikely (because of the lack of mass), but now with dark energy (which is accelerating the universal expansion), it is even more unlikely to recollapse.



3a. In view of the adoption of ‘useful fudge factors’ are we really in any position to categorically rule out the word “cyclic”. Coming back to Korzybski, verbal plasters may only cover over the chasms in understanding, Maybe ‘cyclic’ evokes unhelpful connotations. Maybe we should be thinking of a Universe where mere words like ‘beginning’ and ‘end’ have no cosmic meaning. I think it is sometimes a failing, as well as a blessing, that homo sapiens insists on ‘knowing all about everything’. His quest for truth may result in his ignorance. Is the Universe, whatever it is, a closed system? And are we addressing only the <5%?



4. Are we limiting our thinking on possible cyclic universes to recycling the 'same old' Universe phases/components in total negation of the fact that we really know nothing about >95% of the observable universe?



4. Apart from the unlikelihood of a cyclic nature of our universe, I don’t think so. Everything in our universe exists (whether or not we know what it is and understand it), so if we did have a cyclical universe, I don’t see why there would be problems with recycling matter/energy. Presumably the universe at the quantum level (and the forces/energy therein associated) would be the same from cycle to cycle. I suppose with each big bang event there could be minor fluctuations in forces and constants (mass of electron, for example). I hadn’t thought about this from the perspective of what differences (if any) might interfere with the cycle, and that is interesting. We could certainly end up with universes where the constants are tweaked such that atoms can’t form, or fusion can’t take place. Again, though, a cyclical nature of the universe is not on the cards for us.



4a. Much of this was dealt with in 3a. I would like to reconsider the word ‘cyclic’. Maybe we should be thinking of a Universe where mere words like ‘beginning’ and ‘end’ have no cosmic meaning. They are just words we invented, and have no underlying reality. Mere ‘grunts of a partially evolved ape’, one might think.



So let me replace all of the foregoing with a somewhat shorter version.



We have a very adequate Big Bang Theory (more correctly, as you point out, Inflationary Model/Theory) which, however, is based on an insubstantial base where the division by zero (r) invalidates using the laws of physics.




I believe that the layman, looking at the suggested beginning – an infinitely small concept at infinite density and temperature, might find ‘bursting out of nothing rather less palatable than an honest admission that we do not know, and probably have no means of knowing, the ultimate precedent of inflation. On this occasion, might he not be correct?



Thank you for the most interesting responses, which I value highly, and for your time in considering what are, in fact, metaphysical questions.



Cat :)
Hi Cat! Let me start with ‘running the film backwards’: Essentially what I mean here is that because the universe is expanding, if we go backwards in time, we will see the universe is contracting. Locally, yes, we would never reproduce exactly what has happened, but on the large-scale, we would. This is how we determine physical states (temperature, density, pressure) to test our models (in some cases in the particle accelerator, in others in nature via cosmic rays, regions near black holes, in jets of Active Galactic Nuclei, etc.).

Our expectations, predictions, and models of the early universe must lead to a universe we see today (this is one way we can test our models and hypotheses).

Indeed, this is exactly why we need to have a period of inflation a fraction of a second after the big bang. If we assume the expansion has been linear over time, the earliest universe is too big and leads to a problem of isotropy and uniformity: The temperature of the universe (via the Cosmic Microwave Background radiation field) is far too smooth (i.e., deviations in temperature are so small), implying that the universe was smaller than expected (by the original BBT) a fraction of a second after the big bang. Allowing the temperature fluctuations to smooth in this small(er) early universe, and then Inflating it by 50 orders of magnitude solves the isotropy issue and leads to a universe we observe today.

As for not knowing 95% of the universe, I think some clarification is in order: We don’t yet know what constitutes dark matter and the fundamental nature of dark energy. BUT we do know how they behave and what effects they have on the universe as a whole and the 5% we do know explicitly. For example, whatever dark matter is, it has mass (or behaves as if it does), and it affects normal matter in the “normal” way. It would be nice to know what dark matter is, and, indeed, is vitally important to know what it is. But not knowing what it is, is not the same as saying that we don’t know about 95% of the universe.

Cyclic: In the sense of a universe expanding, stopping, and contracting, I think we can say with some definiteness that that won’t happen.

I would agree with you about “beginning” and “end”.

Dr Joe

P.S. One issue with this topic is that we are dealing with quantum mechanics, and QM is not intuitive (or at least doesn't follow the everyday experience of humans as we interact with the nature).
 

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I have some questions that I need an urgent answer

(Where there is a place on Mars with -63 degrees (I would love if it would be with a picture

Hi Uria500! I’m sorry, but I will need a bit for info: Do you mean a temperature of -63 degrees? This seems to be the average surface temperature of Mars in Celsius, so I imagine it is that temperature many places on the surface.

Dr Joe
 

Catastrophe

"There never was a good war, or a bad peace."
Hi Cat! Let me start with ‘running the film backwards’: Essentially what I mean here is that because the universe is expanding, if we go backwards in time, we will see the universe is contracting. Locally, yes, we would never reproduce exactly what has happened, but on the large-scale, we would. This is how we determine physical states (temperature, density, pressure) to test our models (in some cases in the particle accelerator, in others in nature via cosmic rays, regions near black holes, in jets of Active Galactic Nuclei, etc.).

Our expectations, predictions, and models of the early universe must lead to a universe we see today (this is one way we can test our models and hypotheses).

Indeed, this is exactly why we need to have a period of inflation a fraction of a second after the big bang. If we assume the expansion has been linear over time, the earliest universe is too big and leads to a problem of isotropy and uniformity: The temperature of the universe (via the Cosmic Microwave Background radiation field) is far too smooth (i.e., deviations in temperature are so small), implying that the universe was smaller than expected (by the original BBT) a fraction of a second after the big bang. Allowing the temperature fluctuations to smooth in this small(er) early universe, and then Inflating it by 50 orders of magnitude solves the isotropy issue and leads to a universe we observe today.

As for not knowing 95% of the universe, I think some clarification is in order: We don’t yet know what constitutes dark matter and the fundamental nature of dark energy. BUT we do know how they behave and what effects they have on the universe as a whole and the 5% we do know explicitly. For example, whatever dark matter is, it has mass (or behaves as if it does), and it affects normal matter in the “normal” way. It would be nice to know what dark matter is, and, indeed, is vitally important to know what it is. But not knowing what it is, is not the same as saying that we don’t know about 95% of the universe.

Cyclic: In the sense of a universe expanding, stopping, and contracting, I think we can say with some definiteness that that won’t happen.

I would agree with you about “beginning” and “end”.

Dr Joe

P.S. One issue with this topic is that we are dealing with quantum mechanics, and QM is not intuitive (or at least doesn't follow the everyday experience of humans as we interact with the nature).
Thank you very much indeed Dr Joe, for a most comprehensive answer. Again, it really is very much appreciated. Cat :) :) :)
 

DrJoePesce

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Hello Astro Enthusiasts - It's been quiet here. So I will add some excitement.

Did you see the latest?


The most distant galaxy discovered so far - at 13.5 billion light years (just under 300 million years after the big bang)!

The distance is confirmed at the 99.99% level, but we like to do better than that. This will then be a good candidate for the new JWST when it comes online.

This is the sort of observation we will see more of in the coming years, both with existing telescopes like the Atacama Large Millimeter/submillimeter Array and it's ground-based colleagues, and the JWST.

Enjoy!

Dr Joe
 

Catastrophe

"There never was a good war, or a bad peace."
Dear Dr Joe, thank you for that most interesting link. Being more interested in cosmology and planetary science, this does raise perhaps a naive question from me about stars.

After having it dummed into my brain for approaching 70 years that stars will only ever be seen as points of light, I am just getting used to the idea that larger stars will even appear as disks. So my question is, are we yet able to observe sunspots on other stars, and will we have the resolution to distinguish these from exoplanets? Thanks in advance, Cat :) :) :)
 

Jzz

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After having it dummed into my brain for approaching 70 years that stars will only ever be seen as points of light, I am just getting used to the idea that larger stars will even appear as disks. So my question is, are we yet able to observe sunspots on other stars, and will we have the resolution to distinguish these from exoplanets? Thanks in advance, Cat :) :) :)
It was my impression that exo-planets, given the physical parameters with regard to size, and luminosity, would be impossible to see from any great distance. Their presence can only be inferred by secondary signs. Even given this restriction, it is possible to gain quite a lot of information about the exo-planet as for instance its size, mass and so on.
 

Jzz

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The most distant galaxy discovered so far - at 13.5 billion light years (just under 300 million years after the big bang)!
Dear Dr Joe,

Nice to have your expertise on tap! Thank you for your help. I am a bit confused, according to several of your earlier statements (#107), it is manifest that the early Universe is moving away from us at phenomenal rates. Yet in the article referenced repeated references are made to this very early Galaxy having a very strong ultra-violet signature, as if, to all purposes it were standing still. Here is a quote:

“These stars, called Population III stars, are believed to produce much higher levels of ultraviolet light than typical stars, potentially explaining HD1's brightness.”

If the Universe were truly expanding at the rates that have been “calculated”, surely the ultra-violet should have morphed into the micro-wave range ?
 

Catastrophe

"There never was a good war, or a bad peace."
It was my impression that exo-planets, given the physical parameters with regard to size, and luminosity, would be impossible to see from any great distance. Their presence can only be inferred by secondary signs. Even given this restriction, it is possible to gain quite a lot of information about the exo-planet as for instance its size, mass and so on.
Thank you for your contribution.

However, it does not address my question to my satisfaction, and I look forward to hearing from the person to whom I addressed my question.

Nevertheless, I do thank you for making some attempt to provide a partial answer. FYI my question referred to improved resolution becoming available from new and future equipment, and I am asking Dr Joe's opinion.

Cat :) :) :)
 

Jzz

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Nevertheless, I do thank you for making some attempt to provide a partial answer. FYI my question referred to improved resolution becoming available from new and future equipment, and I am asking Dr Joe's opinion.
Understood and appreciated. However, my intention in answering your question was to illustrate that it was the same problem that affects optical microscopes trying to make out atoms! In any case I am sure Dr Joe Pesce will answer your question. My two-bits shouldn't be taken as being a substitute for Dr. Joe Pesce!
 
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Jzz

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Dr Joe Pesce,

Science programs dealing with planet 9 are proliferating, the possibility of planet 9 existing are based on a high probability. Compared to planet 9, pluto the former planet 9 and now considered to be a dwarf planet, has a size much smaller than our moon but the hypothetical planet 9 will have a mass 10 times that of the earth. This being so, how would it affect Mercury’s orbit? Or could it at any time have disturbed Mercury’s orbit to the extent that it accounts for the slight anomalies observed today?
 
Jun 1, 2020
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As a teaser while we await a better response, no doubt, from Dr. Joe, we do already have disk images of a few giant stars like Betelgeuse.

Exoplanets, perhaps a dozen or more, have been imaged directly, but this is usually only capturing their very dim light, so they are still point-sources of light. An optical telescope would need to have mirror over 20 km to see Jupiter-sized exoplanets out to, say, 50 lyr.

But we have radio telescopes using interferometry to achieve the resolution required, but this is right down Dr. Joes lane so.... :)
 
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Apr 17, 2022
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Subject: Ethics on Cosmic Scale, Directed Panspermia, Outer Space Treaty, Technology Assessment, (and Fermi's Paradox)

Dear Prof. Dr. Joseph Pesce,

due to my only recent realization on this message's subject matter - I'd like to use this contact opportunity in an attempt to raise awareness of what I'm by science convinced of being the ethically most important subject for all of humanity's future, due to its inherent immense risk for the future of sentient beings in general: Natural & especially Directed Panspermia. And I think this topic deserves far more serious care and attention, especially from the International Center for Technology Assessment (ICTA). Further insightful elaboration & scientific sources on the topic can be found here: https://longtermrisk.org/the-importance-of-wild-animal-suffering/ .

Claim: The existence of recent projects alike Breakthrough Starshot & the Genesis Project strongly indicate that there is no prohibition of Directed Panspermia currently in the United Nation's Outer Space Treaty, which I think - at least until sufficient research and ethical evaluations are done, which admittedly may take decades or centuries even - is desperately needed & of imperative importance. However, a fast development of a global, international, emotionally intelligent consensus on voluntary self-restraint in regards to Directed Panspermia type projects, out of respect & care for how riskfully consequential such projects can be, may be even safer and hence preferable.

To be questioned & investigated rationale for this claim: The topic is too vast & complex for me to concisely elaborate on all potentially relevant aspects (that I'm aware of) of it in here, so I'd like to summarize the main points of my & others' concerns: If we take earth's historical evolution of life as reference point for orientation & if there is plausible reason to assume that the majority of prehistoric life - by means of the widespread presence of pain-receptors & some forms of sentience - was not only, but also filled with suffering of therein involved many billions of species each consisting of many animals at any given time across a few billions of years, and to the extent to which this may all in all amount to unutterable extents of misery, then even if it is the case for earth that humanity is for the foreseeable future the only - and thereby critically important - species capable of finally turning this otherwise possibly almost endless misery into an overall pleasant existence e.g. using lab-grown meat and technological breakthroughs alike it, it still remains to be uncovered if even just locally this misery can in any form be compensated for, and there's no guarantee. Now, if there is reason to believe that one can generalize or extrapolate from earth's case to a sufficient variety of exoplanets (or celestial bodies in general), especially if it cannot even ever be ensured that colonies on exoplanets would treat the topic of Directed Panspermia carefully themselves, this may constitute a strong argument against rushing developments towards such projects.

As reminder: The climate, biological and nuclear and chemical threats, autonomous A.I., microplastic, and other topics - in our history, humanity had to learn after mistakes were already made. While for these cases the - still devastating - consequences may be more limited in scope, I think when it's about the cosmos, it'd be wiser to approach this matter in a more reluctant, mindful manner, with long-term foresight, and without forgetting about ethics.

Also, on the topic of Fermi's Paradox, it might be worthwhile considering the plausibility of the following hypothetical explanation:

=== Ethical explanation ===

It is possible that ethical assessment of general forms of evolution of life in the universe constitutes the central issue which intelligent alien species' macroscopic decision-making, such as for the topic of natural [[panspermia]], [[directed panspermia]], [[space colonization]], [[megastructures]], or [[self-replicating spacecraft]], revolves around. If the result of [[utility]] evaluations of enough and sufficiently in time extended initial or lasting portions of expected or prospective cases of evolution is among all other ethically relevant factors the dominant ethical concern of intelligent alien species, and if furthermore a large enough negative expected utility is assigned to sufficiently common forms of expected or prospective cases of evolution, then foregoing directed panspermia, space colonization, the construction of megastructures, sending out self-replicating spacecraft, but also active attempts to mitigate the consequences of interplanetary and interstellar forms of natural panspermia may follow. While in the case of [[space colonization]] it might ultimately stay too uncontrollable to - by technical or educational means - ensure [[settlers]] or emerging [[space colonies]] themselves consistently keep acting in accordance to the awareness of by [[colonizer]] considered major ethical dangers accompanying physical interstellar [[space exploration]], and for the case of interstellar self-replicating spacecraft, due to potential prebiotic substances in [[interstellar clouds]] and exoplanets' atmospheres and soils, it may forever stay impossible to ensure their [[Sterilization (microbiology)|sterility]] to avoid contamination of celestial bodies which may kick-start uncontrollable evolution processes, reasons to forego the creation of a megastructure, even if such may be beneficial to an intelligent alien species and also to some other intelligent alien species imitators, may mainly have psychological origin. Since certain megastructures may be identifiable to be of unnatural, intelligent design requiring origin by foreign intelligent alien species, for as long as the by an intelligent alien species expected number of (especially less experienced or less far developed) from them foreign intelligent alien species capable of identifying their megastructure as such is large enough, the by them rather uncontrollable spectrum of interstellar space endeavor related influences this may have on those foreign intelligent alien species might constitute a too strong ethical deterrence from creating megastructures that are from outer space identifiable as such, until eventually a lasting state of cosmic privacy may be attained by natural or technological means.

This would be all. Thank you for reading, and especially in case of interest & understanding.
 

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Thank you all for your patience. I have a strange anomaly which (some times) doesn't show new messages or replies (no matter what I do), so that means I (some times) see your posts with a delay.

More soon! :)
 

DrJoePesce

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Dear Dr Joe, thank you for that most interesting link. Being more interested in cosmology and planetary science, this does raise perhaps a naive question from me about stars.

After having it dummed into my brain for approaching 70 years that stars will only ever be seen as points of light, I am just getting used to the idea that larger stars will even appear as disks. So my question is, are we yet able to observe sunspots on other stars, and will we have the resolution to distinguish these from exoplanets? Thanks in advance, Cat :) :) :)
Hi Cat – yes, the vast majority of stars are only seen as point sources, because they are so small and so far from us. However, our technology improves all the time.

For very large stars (for example, Betelgeuse and Antares), and a handful of others, we can indeed resolve their surfaces and detect sunspots (or star spots).

This is in fact an issue with exoplanet research, especially for those methods relying on detection of brightness variations of the host star. As you correctly point out, if we detect brightness variations of a star it could be an exoplanet, or it could be a star spot. We do, in fact, detect star spots by detecting brightness variations, so this is an area that needs to be understood very well before we are confidant of an exoplanet detection. Having said that, star spots are generally short lived while a planet hopefully isn’t! That is one way we can distinguish between a dark spot on the stellar surface and a bona fide exoplanet.

Dr. Joe

P.S. Here is a fun observation - a bit different than what we discussed above, but still a resolved Antares - in the radio:

 
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DrJoePesce

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It was my impression that exo-planets, given the physical parameters with regard to size, and luminosity, would be impossible to see from any great distance. Their presence can only be inferred by secondary signs. Even given this restriction, it is possible to gain quite a lot of information about the exo-planet as for instance its size, mass and so on.
Hello Jzz – Two problems with exoplanet detection are they are very small, and their host star is very bright (at least compared to the planet). As you note, the main methods of exoplanet detection are, indeed, indirect and secondary. Also, as you note, a lot of information is still possible from these secondary methods: For example, if we observe eclipses of the host star by an exoplanet passing between the star and us, we can determine orbital parameters, the period (time it takes to orbit the), and mass. Similarly, if we are detecting velocity variations in the host star by the gravitational tug of the exoplanet, we can determine a host of physical properties. There are some exoplanets we can image directly; think big ones, like Jupiter or larger, and if they are a bit more distant from their host star. This is improving all the time given advances in technology.

By the way, currently we can detect large exoplanets more easily than small ones (even though we have detected small ones too in certain situations): The statistics show a preponderance for these larger objects. This is just a “selection effect” that will be resolved as technology improves and the smaller ones start to show up for us.

Dr. Joe
 

DrJoePesce

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Dear Dr Joe,

Nice to have your expertise on tap! Thank you for your help. I am a bit confused, according to several of your earlier statements (#107), it is manifest that the early Universe is moving away from us at phenomenal rates. Yet in the article referenced repeated references are made to this very early Galaxy having a very strong ultra-violet signature, as if, to all purposes it were standing still. Here is a quote:

“These stars, called Population III stars, are believed to produce much higher levels of ultraviolet light than typical stars, potentially explaining HD1's brightness.”

If the Universe were truly expanding at the rates that have been “calculated”, surely the ultra-violet should have morphed into the micro-wave range ?
Hi Jzz – I’m glad you are thinking about these things! And good catch. Let me try to make the early universe a bit clearer (pun intended!).

Generally, whenever there is a discussion about the early (or earlier) universe (and objects therein), such as the quote you highlight, we are talking about the universe/environment in situ, at the physical location (and time) of those objects. So, following the example you mention: The ultraviolet light from the Population III stars is from when they were young. Those objects observed TODAY by us would indeed be in a different wavelength.

Of course, you pulled the quotation from the link I posted discussing the most distant galaxy observed to date. Note the observation was with the Atacama Large Millimeter/submillimeter Array (ALMA), observing in the millimeter portion of the electromagnetic spectrum. AT THE SOURCE, that light would have been emitted in the ultraviolet region, as you state.

Hope this helps!

Dr. Joe

For those just chancing on this post, here is the link I mention above:

https://www.space.com/most-distant-galaxy-discovered-yet
 

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Dr Joe Pesce,

Science programs dealing with planet 9 are proliferating, the possibility of planet 9 existing are based on a high probability. Compared to planet 9, pluto the former planet 9 and now considered to be a dwarf planet, has a size much smaller than our moon but the hypothetical planet 9 will have a mass 10 times that of the earth. This being so, how would it affect Mercury’s orbit? Or could it at any time have disturbed Mercury’s orbit to the extent that it accounts for the slight anomalies observed today?
Jzz – This is a bit out of my realm of expertise. But let’s unpack a bit. Since you mention Mercury, are you talking about the anomalies explained by relativity? All gravitating masses in the solar system are affecting all other objects, to greater or lesser extent. But the Mercury anomalies are primarily caused by the Sun and are well described by relativity as such.

As for planet 9: There are a lot of objects beyond the orbit of Pluto. Indeed, I would expect there to be very many Pluto-like objects – small, so difficult to detect. I would expect (but could be wrong) that gravitational anomalies from a potential higher mass planet 9 would likely be affecting Uranus and Neptune (and Pluto perhaps) more than objects in the inner solar system.

Hope this helps! Dr. Joe
 

Jzz

May 10, 2021
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Jzz – This is a bit out of my realm of expertise. But let’s unpack a bit. Since you mention Mercury, are you talking about the anomalies explained by relativity? All gravitating masses in the solar system are affecting all other objects, to greater or lesser extent. But the Mercury anomalies are primarily caused by the Sun and are well described by relativity as such.

As for planet 9: There are a lot of objects beyond the orbit of Pluto. Indeed, I would expect there to be very many Pluto-like objects – small, so difficult to detect. I would expect (but could be wrong) that gravitational anomalies from a potential higher mass planet 9 would likely be affecting Uranus and Neptune (and Pluto perhaps) more than objects in the inner solar system.

Hope this helps! Dr. Joe
Thank you Dr Joe, very helpful answer.
 

Jzz

May 10, 2021
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Hi Jzz – I’m glad you are thinking about these things! And good catch. Let me try to make the early universe a bit clearer (pun intended!).

Generally, whenever there is a discussion about the early (or earlier) universe (and objects therein), such as the quote you highlight, we are talking about the universe/environment in situ, at the physical location (and time) of those objects. So, following the example you mention: The ultraviolet light from the Population III stars is from when they were young. Those objects observed TODAY by us would indeed be in a different wavelength.

Of course, you pulled the quotation from the link I posted discussing the most distant galaxy observed to date. Note the observation was with the Atacama Large Millimeter/submillimeter Array (ALMA), observing in the millimeter portion of the electromagnetic spectrum. AT THE SOURCE, that light would have been emitted in the ultraviolet region, as you state.

Hope this helps!

Dr. Joe

For those just chancing on this post, here is the link I mention above:

https://www.space.com/most-distant-galaxy-discovered-yet
Greatly appreciate the clarification. Although I have to state that using the relativistic red-shift to explain the expansion of the Universe still does not sit to well with me.
 
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Jzz

May 10, 2021
101
50
660
Generally, whenever there is a discussion about the early (or earlier) universe (and objects therein), such as the quote you highlight, we are talking about the universe/environment in situ, at the physical location (and time) of those objects. So, following the example you mention: The ultraviolet light from the Population III stars is from when they were young. Those objects observed TODAY by us would indeed be in a different wavelength.

Of course, you pulled the quotation from the link I posted discussing the most distant galaxy observed to date. Note the observation was with the Atacama Large Millimeter/submillimeter Array (ALMA), observing in the millimeter portion of the electromagnetic spectrum. AT THE SOURCE, that light would have been emitted in the ultraviolet region, as you state.

Hope this helps!
Dear Dr Joe Pesce,

Appreciate your commitment to answer questions at this forum and your willingness to put your expertise at our service! That being said, I find some aspects of your answer to me (#120 in this thread) are confusing. Your explanation that light from the most distant galaxy was originally ultraviolet but that by the time it reached us, because of the expansion of the Universe, it had red-shifted into the microwave and infra-red range, while it might hold good for that particular Galaxy does not seem to hold good for others. For instance, the Galex observatory that was in operation from 2003 to 2010 operated solely in the ultra-violet range, yet was able to map stars and galaxies that were 10 billion light years distant. (Hopefully, the James Webb Telescope will be able to do even better.) The significant point is that these observations were made in the ultraviolet range, not ultraviolet that had morphed into the infrared or microwave frequencies. Surely, if the Universe were expanding, it would do so at a uniform rate? Not haphazardly. If the Universe were indeed expanding at the rates being widely proclaimed then it should be impossible to see in the ultraviolet to distances of billions of light years.
Would it be possible to ascertain how these two conflicting theories are being so widely published and what is the reasoning behind such divergent facts?
 
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DrJoePesce

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Greatly appreciate the clarification. Although I have to state that using the relativistic red-shift to explain the expansion of the Universe still does not sit to well with me.
Hi Jzz, redshift is caused by the expansion. Since the expansion is of the fabric of space itself, as the photon is traveling through space, space is literally expanding, causing the wavelength of the photon to be stretched.

For example, 300,000 years after the big bang, the radiation field of the universe was a consistent temperature of around 3,000 K (K = kelvin, the absolute temperature scale, start at absolute zero, or 0 K). The universe would have been as bright as the surface of a star. The cosmic background radiation (at 3,000K) would have a wavelength in the visible (red/yellow) part of the electromagnetic spectrum. Those photons have been traveling through an expanding universe ever since, and their wavelengths have been ever stretched, such that now they have very low energy, are almost at absolute zero (they are about 2.74K) and that equates to a wavelength in the microwave portion of the electromagnetic spectrum: they are the Cosmic Microwave Background, today.

Dr. Joe
 

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