All Activity

A big enough lump of lead, travelling at a relatively big enough speed, would put those numbers to shame. Why is so much of this discussion, so emotionally charged?

More of a "matrix" given the number of people who want in, verses the number of people who want to keep them out; bc they're the real enemy. Blue pill or red?

Relish in your moment of awe and accept the consequences; why am I so special? God was a good got/go to, but all we get now is, dark matter/energy has put a spanner in the works... Your not... 😉 In a lot of way's "genetically fittest" is a feedback loop, IOW your fit enough to live now, tomorrow is anyones guess...

All from Nothing and All for Nothing! In a bit of a human brain the size of half a grain of rice; 57,000 cells, 150 million synapses and 23 centimeters of blood vessels. https://www.sciencenews.org/article/biological-puzzles-human-brain-visual “Webb’s image covers a patch of sky approximately the size of a grain of sand held at arm’s length by someone on the ground – and reveals thousands of galaxies in a tiny sliver of vast universe” NASA’s Webb Delivers Deepest Infrared Image of Universe Yet - NASA All of this from atoms and molecules randomly colliding with one another and for the ephemeral purpose of survival of the genetically fittest. Wasted matter, energy, order and complexity at the grandest of scale. But why am I even aware of all of this? _____________________________________________________________________________________ An Eclectic Look at Serotonin, God and Machines Note: originally destined for the “Serotonin” topic in the psychiatry and psychology section, but diverging too much from the thread’s main subject matter. How many have unnecessarily suffered from psychiatry pursuing a dogmatic serotonin approach to depression. The notion of a genetic defect being compensated by a molecule did not come about solely on account of evidence, but also, I contend, as a way of promulgating a mechanistic worldview. Other explanatory models of depression existed at the time, but a genetic-serotonin model fitted best with a mechanistic worldview. It was also very profitable. But this is only the tip of the iceberg. How many times during our recent history have we unleashed the powers of a godless machine worldview to devastating effect on unsuspecting populations. One only has to think of communism (Pol Pot, Mao Zedong, Stalin) as examples of this view wreaking havoc onto the world. Or how about Hitler’s anti-communist, but scientifically “proven” supremacy of the Aryan race. All the while, materialistic capitalism without a soul was faring no much better with its exploited masses (think Guatemalans picking fruits and vegetables under a brutal sun and a cloud of pesticides). Or still yet Neo-Darwinism with its diminutive role of humanity predicated upon “unassailable” original “truths” for which some are now being brought back into question. There is also more to the story than originally thought. Again, has anyone ever asked how negatively the theory, in its original form, had impacted the world? Rather than pause and think, things just moved along without a mere mention of consequences. Adding to this, everything is still being deducted away and reduced down to fundamentals without reference to context. With all of this said, those clamouring for religion as being the scourge of the earth suffer from a severe state of advanced selective amnesia. Let spirituality rule our inner world even if it only implies sacredly offering back our atoms and molecules to the universe upon passing away. The world leaving us behind will be better off then.

I can see that shock still did not wear off. Mathematicians are extremely good at what they do ,but in my humble opinion they do need to take extra courses in geometry ,vectors and a fluid mechanics . Here is something funny,I hope not that offensive for mathematicians

I would think they'd both be put into action at roughly the same time. That is, as soon as they arrive at the asteroid. While a direct strike vehicle wouldn't need to adjust course near the end of the trip and thus would arrive sooner, I don't know why that time would be significant. Why not? As soon as we spot the asteroid and determine it is a collision risk, don't we know rather precisely how much time we have? Only because of how it was constructed. It easily could have yielded more than 100 megatons. https://en.wikipedia.org/wiki/Tsar_Bomba#Test

It seems to me an indirect method as a gravity tractor, will take much longer to put into action, than a direct method of launching a series of strikes on the asteroid. At least get a few rocket nukes on their way to the object. We don't know how much time we have. We don't want to be late in saving the world from massive destruction. There is no 100-megaton nuke. Tzar Bomba was less than 58 megatons. Better to send what we already have thousands of small nukes to "fine-tune" changes to the object's trajectory. You blast it with one and measure the response, then hit it with another. It will be rotating, but that's ok, just keep pushing it in the same direction.

I'm sure you found the instructor to individual time extremely useful. Lol perhaps a bit too much instructor to student time in your case lol. I can certainly understand your class mates sentiment. Good thing physics is useful in a wide range of trades beyond being a physicist.

Nice alternative method list on that link. Several mentioned there that hasn't been mentioned this thread. I did previously mention kinetic impact but no one has spent any examining that option. Didn't know about that particular test though thanks for sharing. @Ken Fabian I particularly like the first article in so far as it included fuel consumption as well as a dollar value given in 1995 roughly. Thanks for sharing that link as well. That low deflection value you gave over time is accurate however as you only need enough deflection to miss the gravitational keyhole the needed deflection only requires 20 days but if process starts in the later on that can change to 135 days or greater explained in the first link.

Just something I found on Wikipedia... https://en.wikipedia.org/wiki/Asteroid_impact_avoidance#:~:text=An object with a high,a spacecraft with the asteroid.

I’ll be replacing an exterior threshold tomorrow myself so long as the weather holds. Once that’s done, I’ll proceed with laying down new decking on the uneven joists I flattened and graded After a few days dangling with my feet ten feet over the ground using sharp tools, they’re even now

That's fair nukes are one option. The detail many are missing though is that we're also not restricted to a single 1 ton craft for the towing. The first link you supplied gets deflection in 20 days in the examination it did there. I already posted near the beginning of this thread another paper that uses several gravity tractors to greatly speed up the time. Here is a related statement in the paper relating to nukes vs tractor. "operation as well. Finally it is very critical that neither NASA nor any other agency involved in addressing this challenge underestimate the degree to which the international community, both at the state level and that of the general public, will demand to be involved in and ultimately be satisfied with many of the decisions regarding NEO deflection. Fragmentation of the NEO, uncertainty in the execution and the results, and even nuclear explosions and radiation will be of enormous concern to the world public. Where more certain and benign methods are available to accomplish the deflection such instantaneous but risky approaches will not be acceptable. The Gravity Tractor, where capable of meeting the deflection challenge, is both technologically and societally the most preferable deflection option.". I tend to agree with that quoted section. Particularly since a 1 ton craft is trivial compared to the rocket fuel consumption to reach escape velocity. As we all seem to agree on using Apophis then according to this link we simply need to miss an 800 km gravitational keyhole. https://en.m.wikipedia.org/wiki/99942_Apophis As your first link examines this 20 days that it gives is quite reasonable.

I'm with Airbrush on this and think nuclear devices delivered by variants of existing rockets would be the preferred means, probably the only one possible any time soon. Longer term - and I do think meteor defense is best viewed as long term - other options may become possible. Delivered and it is done versus delivered and just getting started. Much more deflection from less payload. Shorter mission times. Uses familiar technologies with lots of existing knowhow and capability. The links people have provided, including yours appear to support that although different asteroid examples and different units make direct comparisons a bit tricky - at least for me. https://arxiv.org/pdf/physics/0608157 with Apophis (320m diameter, 46 million metric tons) as example for a 1 ton gravity tractor - 3.7mm per sec per year (? Someone else should check units and arithmetic?) https://ntrs.nasa.gov/api/citations/20205008370/downloads/Nuclear_Devices_for_Planetary_Defense_ASCEND_2020_FINAL_2020-10-02.pdf with 560m diameter object and 550kg payload - 65 to 165mm per sec in a few seconds to minutes with a single 1 megaton nuclear device for a significantly larger object. Having the device stationary with respect to the asteroid seems to be preferred over one coming at it at high velocity but not sure how that would work directly along the trajectory.They look to smaller than 1 Mt explosions as preferred - several small ones better than one bigger one. Spinning object? Having a quick search for rotation rates - it sounds like a large rubble pile would max out at 1/4 rotation per hour, slow enough for a nuclear detonation to give directional push. Small ones would be suitable for dispersing blasts. Too close to Earth? The "nuclear devices" paper deems several months of warning as a short warning, late response scenario and doing the detonations more than a month out from expected impact is considered a rapid response. I can't see that as an EMP risk to Earth that far out. Anything as close as the moon will be days at most away - too late, kiss arses bye bye. Nukes not designed for use in space? I expect some probably are even if that isn't advertised; the potential for nuclear warfare to happen in space has been known a long time; it may be against arms agreements to put any into space but military planners always look beyond existing treaties if only on an Irish basis - to be sure, to be sure.

My largest class in second year Physics at Brock University, Classical Mechanics, in78-79, had 22 students, only one of whom was a girl. In third year Physics there were four of us. In fourth year, just two. My fourth year course in advanced QM usually had us two and the prof ( Dr. Shukla ) at the bboard writing equations. The other guy ( who was a genious compared to me ) stayed to do a Masters degree; when I ran into him a few years later, he told me he had quit halfway through it, and gone into business/finances because there is no money in Physics

Use the equation of state for a scalar field. The FLRW metric version is a good starting point. https://en.m.wikipedia.org/wiki/Equation_of_state_(cosmology) We already have equations to describe vacuum fluctuations with a pressure term see link. Under GR the stress energy momentum tensor has the pressure terms. This will correspond to how pressure is handled under QFT

Lmao small World indeed. I always thought highly of my time there. Very friendly and supportive environment. Everyone was incredibly helpful.

So now you are saying we DO have the time? Aren't many small bombs the same as one large bomb? We can use 100 small or one large. Basically the same thing I believe.

Precisely when you get right down to it every solution has infrastructure hurdles. I would think it would be far easier to get a gravity tractor solution than it would be convincing every involved government nukes are needed.

We had a couple of pretty good ones when I was a postdoc there.

There’s a treaty preventing nuclear weapons in space (the Outer Space Treaty), which would obviously be suspended in this scenario, but you probably aren’t going to be parking nukes in space in anticipation of hitting an asteroid that hasn’t already been identified as a very likely threat. Multiple parts of the plan would have to be in place beforehand.

That's très cool. As a crude structural carpenter, you folk are like unthinkably advanced aliens to me. My zen thing is more putting in a window or hanging a door, or electrical. Anything is zen that is guided by the need to always know precisely where both your hands are, and that you exist in a bubble of calm quiet. (I did once make a simple mortise, using 4x4 for work table legs and running 1x4 rails into them. Where I learned about keeping chisels sharp...)

No problem quite frankly delivery is a large part of the problem to begin with. We haven't particularly established how much can or can't be reasonably delivered. Obviously we're not firing missiles from Earth to the asteroid so you would need a craft. That craft will determine how big a payload it can deliver.

My NB was in regard to the current arsenals, which were suggested as providing the charges for these hypothetical asteroid deflectors. Am aware of the bad old days of multi-MT blasts. A close relative lived most of his life a couple miles from the nation's foremost nuclear bomber base, and I used to live uncomfortably close to StratCom hq, so have been fairly aware of the arms race history and living in the crosshairs. The main problem with Castle Bravo or Tsar Bomba sized bombs, as mentioned in a following post, is difficulty in delivery of such massive weapons to a target. My reading of this discussion so far is that a smaller charge is easier to deliver to an asteroid, provided you have enough lead time to strike it at a great distance and thus gain the required deflection with less force.

And why did this happen? What about the NEO Surveyor mission, already in the works? Is there some deficiency in that? Do you have any facts or science to present, or is it just going to be a bunch of hand-waving?

I always called it a marking gauge but it’s a simple tool for precise measurements. Hand carved the mortise and tenons on our oak dining room table and the crafting table I made for the kids using one (also inserted a locking dowel / trenail so they’ll never go sloppy)