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Ask Me Anything AMA with Dr. Joe Pesce

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Jun 25, 2020
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Hi.
I wouldn't want to miss this opportunity at all , I am astounded by the cosmos and below are few questions I had.

1) I came about an article which talks about an alternative theory to dark matter. It suggests that information has mass , It states that information is the fundamental building block of the universe, and it has mass and could be missing answer for dark matter. Could you please throw some light around this.

2)also I came across this article which claims that NASA's Antarctic Impulsive Transient Antenna has Detected a Tau-neutrino traveling not from outer space to earth but from the earth's surface to outer space. I wanted to understand what is causing this and could it imply.

3)The the sun is loosing it's mass as a result of solar winds and fusion . So if the sun is loosing its mass then wouldn't it mean that the curve it's create in the fabric of space time is diminishing and with that the gravitational force is also reducing.

4)Recent observations from Hubble has revealed some of the earliest black holes some 13 billion years old which is very close to the age of the universe, how would something so massive exist so early in the universe when even stars were not born.
 
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Jun 25, 2020
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Hi
I aspire be an astrophysicist. I read a lot of books regarding space and science (particularly physics). But I want more exposure to experimental and calculative side of it too. So any suggestions for that?
I'm currently pursuing my b.tech and would very much like to do a Masters and PhD in astrophysics.
What are the things that I should study (topics and materials)as of now that can be helpful later & what are some advices you can give me as a professional.
Please do reply.
Thanks.
 

DrJoePesce

Verified Expert
Mar 31, 2020
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Thanks for answering our questions:).
I had a few questions:
1. Can dark matter form planets and stars? If so can we even detect that or is it that dark matter does not interact with itself?
2. What is the center of a Neutron star like (at least in more widely accepted theories)?
3. Do neutron stars start as Magnetars and then slowly lose their magnetic field's immense strength?
4. Do you think Europa has life underneath its surface?
Good morning!

A1. Dark matter particles are probably subatomic and weakly interacting, apart from having mass (and hence gravity), otherwise we probably would have detected them by now. So, no, probably can’t form planets and stars.

A2. Short answer: a neutron star is almost all neutrons, at extremely high density. BUT, those densities are so high we don’t really know what the properties of matter are.

A3. Maybe. But the magnetic fields of an neutron stars vary, so magnetars are just those with the highest magnetic fields.

A4. In the ocean? Maybe. This is why Europa is one of the planned targets for robotic exploration.
 
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DrJoePesce

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Mar 31, 2020
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Is it possible that there is variations in the density of the higgs field, resulting in fluctuations in the weight of mass depending on where in space the mass is?
If so, could this explain the deviations we observe and currently explain with dark matter?
Good morning Helmer!

This is not my area of expertise, so with that warning…. The Higgs field, modulated by the Higgs boson, is what gives mass to particles. I’m not sure we need to call upon density fluctuations of the field to give different masses, though. Almost certainly the mass of the dark-matter particle derives from the Higgs field and boson.
 
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DrJoePesce

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Talking to an astrophysicist is one of the things on my bucket list, so thank you for making yourself available to us Plebs! :)

What a great honor for me to be a part of this for you, TimMyth!! ☺

First question: When I see maps of the universe that show galactic clusters, I always wonder if they are adjusted for the travel time of the light. That is, when I'm shown a map that marks Andromeda, am I being shown where it was ~2.5 million years ago when the light in the picture left, or has it been adjusted for its expected present day position even though we won't know exactly where its at for another 2.5 million years?

Excellent question – a first for me! Positions of astronomical objects are not corrected for time. They are plotted on 2-D using a coordinate system similar to latitude and longitude on Earth. If we have distance info, then we can plot the third dimension. By the way, we really don’t know where a particular object is today, apart from some relatively nearby galaxies we can model with computer simulations. For example, we don’t k now exactly where Andromeda is at this particular moment, but we know it is falling towards the Milky Way and vice versa, and we will collide with it in the future.

Second: Current models of the Big Bang show a period of rapid inflation in the beginning. I'm assuming that only the lightest of elements appeared in the beginning since heavier elements are formed from the novas of stars. I'm also assuming that solar winds push lighter elements further and faster than heavier elements. Could this account for the rapid early expansion?

Yes, that period of inflation is why the Big Bang theory is actually called the Inflationary model. All hydrogen and most of the helium were formed in the Big Bang. As you correctly point out, heavier elements come from massive stars (from fusion when they are alive and from their supernova explosions when they die), and a few other processes. The inflationary period probably has nothing to do with elements. And, it occurred before hydrogen was created. Rather, it appears to have something to do with the fabric of space itself. Dark Energy, which is causing the rate of universal expansion to increase, began about 1 billion years ago, and is probably related (the same phenomena) as that which occurred during the inflationary epoch of the Big Bang. (Regarding, the solar wind: The solar wind is a flux of particles (protons and electrons) flowing off the surface of the Sun. There are various elements in the Sun, on the surface, and flowing off, but they are in relatively minute quantities. Rather, in the Sun, but more commonly in red giant and supergiant stars (which have a much more robust wind and which experience significant mass loss through that wind), dust forms when the temperature of the expelled plasma gets low enough, and that dust (stuff like titanium oxide, carborundum, silicon dioxide, etc.) gets pushed away by the wind. And certainly tge lighter stuff is more easily pushed away. But this is a different process than inflation/dark energy.

Lastly (since I see you have an interest in inter-species communications): Are you aware of any species that clearly communicate with another species? And I don't just mean parasitic communications where one species has learned danger is nearby when some other species makes a certain sound, nor do I mean people teaching sign language to one particular animal. I'm wondering if, for example, an ant can lay a trail that a beetle can follow and vice versa. Or maybe a dolphin is able to find a school of tuna thanks to a heads up from a pod of whales.

I know of species that try to communicate with each other, but I’m not sure if they are able to do so. However, I would maintain that what you call parasitic communication (and your example of danger sounds), is, in fact, communication. Other animals communicate with us: Lots of examples, but, for example, honeyeaters (birds in Africa) communicate with humans to get help opening bees’ nests. We could debate what communication means, but I think this satisfies the most basic definition of communication.

Again, thanks for taking the time to answer silly questions that I could probably answer for myself with a few minutes of googling.

No questions are silly! Keep up the inquiring mind!
 
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DrJoePesce

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Regarding the topic of how LIFE got started on earth:

Life on earth endured at least 5 extinction level events and bounced back each and every time, whether it be in the form of plants and grasses and primitive simple life in the seas or more complex life forms such as dinosaurs that dominated the planet for 100's of millions of years before being wiped out by a catastrophic impact by an asteroid or comet and even then life bounced back giving mammals there foot hold to evolve.

If other earth-like planets are found and somehow verified and if life is found to be common place among habital liquid water sustaining rocky worlds and if life basically forms in the same way through-out the cosmos as it did here on Earth.....

How plausible would it be to discover a world (an Earth II) where life did start much the same way as here at home. Where life followed the same evolutionary paths with lots of different circumstances and one of those circumstances being that no catastrophic collisions between that life bearing world and any cosmic debris took place and no catastrophic climate changes took place. Is it possible that dinosaurs could be the dominant form of life on another world?
Hello WildSoftail!

Certainly, anything is plausible – but this is all speculation (though it would be great to find out!).

Given the complexity of the chemical, physical, and biological environments on Earth, and the various events that have happened (asteroid bombardment, a moon, stellar activity, volcanism, etc.) over 5 billion years, I think it’s unlikely we would give a completely identical environment on another planet. But there are probably a lot of planets, so it’s possible.
 
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DrJoePesce

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Mar 31, 2020
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I was watching a show about the sun and it said the suns gravity extends for at least two light years. then I watched a different documentary and it said that the gravity of the sun extends for one light year. What is the truth behind this?

Hey WGA!

I haven’t seen what you did, so don’t know exactly what they are talking about, but 2 light years might be a clue. It could be they were talking about the gravitational influence of the Sun compared to the nearest star, the alpha Centauri system just over 4 light years away. If I’m floating in interstellar space and get close to the Sun, I will be attracted to it (and likewise if I’m close to alpha Centauri, I will be attracted to it). At a VERY general level, if I’m within about 2 light years of the Sun, it’s gravity will be win out over the alpha Cen system, and if I’m more than 2 light years from the Sun, alpha Cen’s gravity will win. This isn’t EXACTLY true because there are three stars in the alpha Centauri system, so it has more mass (and hence gravity) than the solar system does, so that maybe that’s where the one light year number comes from. I don’t know what the exact sphere of gravitational influence of the Sun is.

They might have been talking about something else, but I can’t know what! ☺

I should note: The force of gravity becomes weaker with distance very rapidly, but there is still a force, no matter how small. So, the Sun’s gravity extends everywhere, and affects objects in the center of our Milky Way, or in the Andromeda galaxy, or wherever in the universe – just at a minute level!
 
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DrJoePesce

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I'm going to buy a new telescope. I have not used a telescope yet, but I what to see nebula, deep space objects and the closest superior planets in detail and my budget is about $500. What would you recommend? Refractory is my best bet, correct, but magnification and lens length would be a good choice? Thank you.
I can’t suggest specific resources, but there are a lot of them out there and I encourage you to explore. You mentioned what your goals are and that’s great! Think about them even more. Study the astronomical objects you want to observe, learn the constellations, and only then should you start to research telescopes and equipment (and you might want to even consider binoculars).

Good luck, and keep looking up!
 
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DrJoePesce

Verified Expert
Mar 31, 2020
62
175
210
Hi.
I wouldn't want to miss this opportunity at all , I am astounded by the cosmos and below are few questions I had.

1) I came about an article which talks about an alternative theory to dark matter. It suggests that information has mass , It states that information is the fundamental building block of the universe, and it has mass and could be missing answer for dark matter. Could you please throw some light around this.

2)also I came across this article which claims that NASA's Antarctic Impulsive Transient Antenna has Detected a Tau-neutrino traveling not from outer space to earth but from the earth's surface to outer space. I wanted to understand what is causing this and could it imply.

3)The the sun is loosing it's mass as a result of solar winds and fusion . So if the sun is loosing its mass then wouldn't it mean that the curve it's create in the fabric of space time is diminishing and with that the gravitational force is also reducing.

4)Recent observations from Hubble has revealed some of the earliest black holes some 13 billion years old which is very close to the age of the universe, how would something so massive exist so early in the universe when even stars were not born.
Good morning Vijay.menon09!

A1. That’s really intriguing! I had not heard that suggestion, and I will have to look into, and think about, it more.

A2. I’m not aware to which article you refer. But some thoughts…. Neutrinos interact very rarely with other particles/matter, which is why they are so difficult to detect. Billions of neutrinos are flowing through every square centimeter of Earth (and us!) every second. Which means that in Antarctica, for example, neutrinos are coming in directly from space (that is, from above), but they are also flowing up from the other side of Earth, THROUGH the Earth and the ice sheet. They are coming from space, just through Earth first. I think this is what the article meant.

A3. The Sun is indeed losing mass though the solar wind, but it’s a minute fraction of the overall mass. However, later, when the Sun is nearing the end of its life and it becomes a red giant, it will lose a large fraction of its mass through the solar wind – maybe up to half. In any case, as the Sun loses mass, its gravitational field does indeed become weaker. The consequence for us on Earth (and for the other planets) is that our orbit moves farther from the Sun.

A4. Yes, this is an intriguing finding (but note it’s not quite before the first stars were born). Here is an article https://www.space.com/39000-oldest-farthest-monster-black-hole-yet.html

And it’s not only black holes, but big galaxies too (this observation from our ALMA observatory): https://www.space.com/wolfe-disk-massive-galaxy-discovery.html

What this means is we need to understand better how galaxies, and supermassive black holes, form and grow!

By the way, here's a piece on the first stars! https://www.nsf.gov/news/news_summ.jsp?cntn_id=244599
 
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DrJoePesce

Verified Expert
Mar 31, 2020
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Hi
I aspire be an astrophysicist. I read a lot of books regarding space and science (particularly physics). But I want more exposure to experimental and calculative side of it too. So any suggestions for that?
I'm currently pursuing my b.tech and would very much like to do a Masters and PhD in astrophysics.
What are the things that I should study (topics and materials)as of now that can be helpful later & what are some advices you can give me as a professional.
Please do reply.
Thanks.
That’s a great goal! And a background in physics is great even if you don’t go into the field. It sounds like you are doing everything right: a bachelor’s degree in physics (or astrophysics) will give you the physics and mathematics you need. If you are not majoring in physics, then take as many physics and math courses as you would get for that degree. I encourage you to get research experience: Check with your physics/astronomy department to see if they have any opportunities with faculty to do that; look for opportunities in other universities; and check out the Research Experiences for Undergraduates (REU) for excellent programs all over the US (https://www.nsf.gov/crssprgm/reu/). Start looking for graduate schools doing work you are interested in and then reach out to those departments and researchers. Also think about what you want to do after the Ph.D.: Continue in academia or go elsewhere for work. Good luck! I think your plans are fantastic! ☺
 

DrJoePesce

Verified Expert
Mar 31, 2020
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If we alter the past ,is there any chance we are cereating new universe with new possibilities?
Hello Aditi!

Well, we can’t alter the past but certainly our decisions can change what happens in the future. I’m not sure it spins off another universe (as has been discussed at great length in SF and by some physicists). For example, had I not gone to Cambridge University for graduate school, my future would be different. If I had continued my undergraduate research in the atmospheres of red giant and supergiant stars instead of going into extragalactic astrophysics, things would have been different. If my first postdoc were at a different place, the future would have been different. Certainly this is true. Is there a parallel universe where I made different decisions? Maybe. We don’t know.
 

rod

Oct 22, 2019
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Hello Everyone!

Our Very Large Array in New Mexico (https://public.nrao.edu/telescopes/vla/) has 27 antennas that can be moved around (quite a feat for a 200-ton antenna) to different configurations.

Last week they moved them for the first time since the beginning of the pandemic.

See the report here: https://public.nrao.edu/news/nrao-science-continues-despite-virus/
What is the angular resolution expressed in mas units for this tool? Example, V-band light and how small a tiny circle can be seen?
 
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DrJoePesce

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Mar 31, 2020
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What is the angular resolution expressed in mas units for this tool? Example, V-band light and how small a tiny circle can be seen?
Thanks for the question. The resolution depends on the spacing of the antennas and the frequency observed (and, remember, these are radio telescopes), so the resolution ranges from 0.2 arcsec to 0.04 arcsec (for the widest configuration). And that would be 200 to 40 milliarcseconds.
 

rod

Oct 22, 2019
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Thanks for the question. The resolution depends on the spacing of the antennas and the frequency observed (and, remember, these are radio telescopes), so the resolution ranges from 0.2 arcsec to 0.04 arcsec (for the widest configuration). And that would be 200 to 40 milliarcseconds.

Dr, JoePesce, thanks. This is good info here and the array is radio telescopes. 200 to 40 mas resolution, that is something. My 90-mm refractor telescope and 10-inch Newtonian, V-band resolution at best is about 1.5 arcsec or so from 200x or more. Your equipment is better than mine :)---Rod
 

rod

Oct 22, 2019
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FYI, this exoplanet AU Mic b (close to 58 earth mass Neptune type) is in the news cycles now and report at space.com too. Listed about 9.79 pc distance, http://exoplanet.eu/catalog/au_mic_b/

The radio telescope array imaging to 40 mas resolution could see an area about 0.4 AU in diameter at the host star's distance and 200 mas, about 2 AU across. AU Mic has a disk too, some reports indicate the disk is quickly eroding.
 
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DrJoePesce

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Mar 31, 2020
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Dr, JoePesce, thanks. This is good info here and the array is radio telescopes. 200 to 40 mas resolution, that is something. My 90-mm refractor telescope and 10-inch Newtonian, V-band resolution at best is about 1.5 arcsec or so from 200x or more. Your equipment is better than mine :)---Rod
That's great resolution for those telescopes!
 

rod

Oct 22, 2019
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Dr JoePesce, yes that 1.5 arcsec is good at certain times and elevation angles of targets too. Jupiter opposition in June 2019 was something. The June 2019 Sky & Telescope issue reported that amateur telescopes could resolve some of the Galilean moons as small moons or disk shapes because Jupiter was closer to Earth. I enjoyed some great views of Ganymede and Io, double shadow transit event on 12-Jun-19. Those moons were some 1.7 arcsec size at the time. I used my 90-mm refractor and 10-inch running 200x or more. Those two moons were clearly small disk shape as they approached Jupiter's limb and moved across Jupiter. Their shadows very clear and distinct circular size too, especially Ganymede. That was a good test of my telescopes optics and eyepieces able to see some of the Galilean moons - look like moons :) I was out in my horse pastures from 2100 until after 0100 EDT. I live in a more rural area that have horse farms, alpacas, etc. in MD. I also keep a detailed stargazing log using MS ACCESS database. My most recent observation was looking at Antares with M4 in the field of view near 0100 EDT on 22-Jun-2020. I really enjoy getting out into the fields and viewing the heavens. Some solar observing too with glass, white light solar filter.
 
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DrJoePesce

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Mar 31, 2020
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Q: About how often are the VLBA (long baseline) observations done? That has to be tricky.
Thanks Helio – I think you are responding to my post about the Very Large Array (VLA), and as I noted there are a number of antenna configurations (four, in fact), and these follow a schedule throughout the year. And I think by VLBA you mean the configuration with the largest dimension.

But if that's not what you meant, and in any case, let me take the opportunity to mention another one of NSF’s NRAO facilities, called the Very Long Baseline Array (VLBA). This is an observatory consisting of 10 antennas, spread throughout the continental US, Hawai’i, and the US Virgin Island (St. Croix). https://public.nrao.edu/telescopes/vlba/

The longest baseline is Hawai’i to St. Croix, 8,600 km (5,350 miles), providing a resolution of 0.17 – 22 milliarcseconds (mas).
 
Jun 1, 2020
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Thanks Helio – I think you are responding to my post about the Very Large Array (VLA), and as I noted there are a number of antenna configurations (four, in fact), and these follow a schedule throughout the year. And I think by VLBA you mean the configuration with the largest dimension.

But if that's not what you meant, and in any case, let me take the opportunity to mention another one of NSF’s NRAO facilities, called the Very Long Baseline Array (VLBA). This is an observatory consisting of 10 antennas, spread throughout the continental US, Hawai’i, and the US Virgin Island (St. Croix). https://public.nrao.edu/telescopes/vlba/

The longest baseline is Hawai’i to St. Croix, 8,600 km (5,350 miles), providing a resolution of 0.17 – 22 milliarcseconds (mas).
Yes, the VLBA is what I meant.

Is this interferometry something that's done on a regular basis, say, every week or month, or can it often be, as a lady entrepreneur told me a couple decades ago, "Too much squeeze for the juice"?

I assume some efforts have gone into finding the homeworld for the Mandalorians, given our spectroscopic skills and their likely high Fe, Cr, Ni, etc. :) [Well, you can see I'm really asking what you think of this new Star Wars series. ]
 
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DrJoePesce

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Mar 31, 2020
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Yes, the VLBA is what I meant.

Is this interferometry something that's done on a regular basis, say, every week or month, or can it often be, as a lady entrepreneur told me a couple decades ago, "Too much squeeze for the juice"?

I assume some efforts have gone into finding the homeworld for the Mandalorians, given our spectrscopic skills and their likely high Fe, Cr, Ni, etc. :) [Well, you can see I'm really asking what you think of this new Star Wars series. ]
I don't know about a search for the Mandalorian home world :)

The VLBA observes more or less continuously.
 
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Jun 1, 2020
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Great to hear! Do you have optimism for establishing radio telescopes (using interferometry, no doubt) on the "dark" side -- it kinda fits -- of the Moon before those optical folks take all the ice? ;)
 
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