The force of gravity is weak. And not just a little bit weak. It’s so much weaker than the other three fundamental forces—electromagnetism and the strong and weak nuclear forces—that it’s almost impossible to provide analogies.
Gravity isn’t a force. It’s the curvature of spacetime, the bending itself. You can’t compare it to the three other forces.
We can’t see the bulk, touch the bulk, experience the bulk, or otherwise interact with the bulk because our entire universe—all the particles and forces of nature—are restricted to life on the brane.
That means it isn’t falsifiable. It’s same as believing in god - it’s faith and not a scientific theory. Also the article says:
Physicists just need some way to pierce the veil of the brane and peer into the realm of the bulk.
How should physicists do that when by definition a bulk can’t be detected? In the later parts it is claimed that the bulk-brane-interactions somehow influences gravity and that this influence could be detected. I call bullshit.
If our running knowledge of gravity is mistaken
We know that our understanding of gravity is flawed because we can’t unify it with the theory of quantum mechanics. But there must be a link between them.
In 2019, the LIGO detector (…) measured gravitational waves emanating from the merger of a black hole with … something else. The black hole had a mass of around 23 solar masses. Its companion had a mass of only 2.6 solar masses. That’s far too small to be a black hole … but also a little too big to be a neutron star.
Objects with a mass above 2.5 solar masses are likely light weight black holes. Source
The whole article consists only of a lot of ‘could be’, nothing tangible and bullshit.
Gravity isn’t a force. It’s the curvature of spacetime, the bending itself. You can’t compare it to the three other forces.
I do agree but, it is very common in academia to disagree with this, to believe that the geometric representation of gravity is merely a clever trick to approximate gravitational effects, but that in reality it is caused by a force-carrying particle just like any other force, a graviton, and spacetime is flat. That was the basis of String Theory and some other views. I don’t know why this view is so popular but it is.
Just 6 light-years away, Barnard’s Star is a well-studied 10-billion-year-old M dwarf with a mass of 0.16 solar mass. Finding exoplanets around Barnard’s Star has been something of a white whale for astronomers for more than half a century; starting in the 1960s, researchers have claimed to have spotted various planets around Barnard’s Star, from distant Jupiter-mass companions to close-in super-Earths. Each of these claims has been refuted.
Now, the white whale appears to have been caught at last. Just last November, researchers reported the discovery of a planet orbiting Barnard’s Star with a period of 3.154 days. The data hinted at the presence of three other planets, but these candidates could not be confirmed. In a new research article published today, Ritvik Basant (University of Chicago) and collaborators leveraged years of data to confirm that Barnard’s Star hosts not just one, but four planets.
Good summary, but to everyone else reading this, it’s really worth it to read the article. It’s short and yet, frankly, fascinating. It discusses the methods used to identify the exoplanets and their orbital periods.
To think how hard it is to confirm these planets, for such a relatively close star. When we have already confirmed so much about objects at far greater distances.
Hard to comprehend these achievements from our individual perspectives. 👏
I wonder if Kepler or others would have found these planets had Barnard's Star been in the areas searched? I.e., very small planets in close orbits around a dim star is a very difficult target, period. This also means that the thousands of systems we now know about certainly have far more than the few bodies we've detected because we can only see the biggest ones well.
As someone who doesn’t know or understand any of this math/physics. Would you mind doing a super simple explanation of how the calculation works and why you chose certain factors?
Might be a dumb thing to ask but just curious and want to understand more.
D_nominal, D_min, and D_max represent the most likely, minimum, and maximum (well technically not maximum, just 3 standard deviations from most likely, of which 99.7% of trajectories will fall within) distance 2024 YR4 will pass from the center of the Moon (NOT the surface). They're taken from the linked NASA website. R_moon is the radius of the Moon.
L_impact is length of the impact corridor (the line where 2024 YR4 could impact the Moon). Since it doesn't pass through the center of the Moon, it's not simply 2*R_moon and so we need a simple formula to calculate it from R_moon and D_min.
P(x) is a probability density function; it's the black curve you can see. It shows, for a given trajectory along the line of possible trajectories, how likely 2024 YR4 is to follow that trajectory. It's shifted a bit from the center since the most likely trajectories are not exactly centered on the Moon. P_impact is the area of P(x) that falls within +/- L_impact, AKA the probability that the trajectory will intersect the Moon, AKA the impact probability.
The rest is just some graphing stuff that doesn't matter to the calculation.
AKA the probability that the trajectory will intersect the Moon, AKA the impact probability.
(Disclaimer, I know close to nothing about these) Am I pedantic about a useless detail or does it significantly change the probability if we consider that an object may still impact the moon after “missing it” if it comes close enough to be captured and come back after a semi orbit? Or do the relative speeds makes this extremely unlikely?
I’m confused about what exactly the ring is in the image or the main image at least. There seems to be an enhanced image in the article that highlights the ring more clearly as an outer edge, which makes sense (I suppose).
But I don’t understand what I’m to make of the top image. It’s the diffuse light part of the ring?
I was wondering if anyone else has done any kind of astronomy public outreach and if they had any advice to help keep the engagement up when folks are taking turns peeking through the scope.
About 20 years or so, yup. Star parties, observatories, planetaria, etc.
My plan has been to teach the basics of star finding, telescope use, etc.
Don’t do this. The people who are going to show up to look through a telescope at the park do not GAF about how to use a telescope. They want to look through it and be awed by what they see. The work it takes to get to that point is of zero interest to 99.999% of them. Very often, the actual visual image you see is not awe inspiring, though, so you want to spend the time while people are looking through the lens explaining to them what they are seeing, and doing so in very awe-inspiring tones and terms.
Lead them to the feelings that they want to feel. Weave the story that reflects those desires back to them. Do everything you can to make them feel the scope of what they’re seeing. Use the fact that it’s an unimpressive smudge to hammer home just how god damn far away it is they are seeing. Trot out the big numbers. Tell them how far away it is in in light years, and then switch to miles. Reference what was taking place on Earth at the time the light first left its source. Relate it all to the things they relate to or care about.
And treat the telescope like it’s the least important thing of the night until someone asks about it.
Thanks, that all makes sense! I noticed in hindsight that people were a little less jazzed about Trapezium than I was expecting. I mean, they appreciated it, but compared to my own initial reaction in seeing it (I had to go and tell someone right away), it was pretty muted. Sounds like I’ll have to do some homework.
That last line really grabbed my attention.
And treat the telescope like it’s the least important thing of the night until someone asks about it.
Can you elaborate a bit on what you mean here?
Also, I should probably make clear that this is going to be a weekly recurring class that happens at different city parks. I’m trying to get people interested in actually doing amateur astronomy.
Imagine going to a public class on… let’s say playing the electric guitar, and the instructor just keeps going on and on about tuning forks, gear maintenance, and music theory. You were just hoping to learn how to play Stairway to Heaven, despite never having touched a guitar in your life.
The telescope is actually a hurdle to most people who will ever look through one. Introducing people to amateur astronomy by talking about making the sausage doesn’t whet the appetite. It’s dry, it’s small, and it’s boring. And it’s not relevant to 90% of people who will ever show up – they’re not going to race out and spend hundreds of dollars on a worthwhile telescope. It’s the kind of thing you talk about once people are hooked, want to view things independently, and are actually ready to invest their time, energy, and money into the hobby.
Amateur astronomy happens first in the mind. The imagination is accessible; the nitty gritty of operating a manual telescope is actually quite exclusionary, and fails to meet people where they actually are.
This is great advice, I’m very grateful that you responded! I did start out pointing out the constellations and the different features we would look at, but after reading this, I realize now that I got people looking into the scope way too early, and there was basically nowhere left for me to go after that. This also makes me think about doing a separate thing just for helping people get astronomical league certs, then.
Earth-like is a very broad term. If an organism has something similar to DNA or shared any kind of chemical processes it could be “earth-like”.
As an odd hypothetical example, there is a theory that fungi could potentially spread from planet to planet. Even with a billion or so years of independent evolution, fungi on Venus and fungi on Earth could still share some of the same traits.
astronomy
Ważne
Magazyn ze zdalnego serwera może być niekompletny. Zobacz więcej na oryginalnej instancji.