It's easy to pretend to know stuff. Everyone and their mother nowadays seems to be an expert on rocketry.

It's harder to actually know stuff. The most important causes for failure on rockets are engine failures, software failures, and structural failures, in that order. Engine failures are typically caused by excessive vibration, thermal stress, combustion containment failures (hot gases touching the walls), turbopump failures, and a few other reasons, and these will often show up in static tests. In fact this is the whole point of static testing. As for software, it's the same whether you're re-using an airframe or not. Finally, as for structural failures, they are caused by vibration, thermal stress, and aerodynamic stress. Of these, a pretty good picture can be constructed from static testing, with only aerodynamic stresses left out. Granted, a single-engine test isn't very accurate for diagnosing problems; full-rocket static tests are better.

While flying through the air in a normal mission profile puts a lot of stress on the airframe, it doesn't do any irreversible damage on the airframe, unless the rocket is very badly designed. Going outside the mission profile (facing the wind the wrong way) can and will do irreversible damage, but spacex are very careful to bring their rockets down gently. If you want to bet that a recovered falcon 9 first stage can't be used, the only way that argument will work is if you argue that the airframe somehow suffers irreversible damage during the recovery maneuver. Other than this, it would be extremely strange.

You know nothing about rocketry.

A rocket doesn't become damaged and non-recoverable just because it flew for five minutes through the air. The only reason people haven't been able to recover rockets up to now is because the actual act of taking a large moving object at 5000 km/h, decelerating it, maneuvering it through the atmosphere, and landing it gently is really really hard. That, and the thermal stresses on the engines mean that most rocket engines up to now have not been able to sustain multiple full-length firings without refurbishment.

SpaceX has _already_ demonstrated that it has solved both of these problems. The Merlin rockets that SpaceX uses are actually fired around 10 times before even getting mounted on an actual launch vehicle! And no, they aren't 'refurbished' after test firing. The engines have been designed with full re-usability in mind - fill up the tank again and go. The launch vehicles themselves go through static firings before being launched through space. In static firings they get most of the vibration and thermal stresses that they would get if they were actually flying (most of these stresses come from the rocket engines). The point is that SpaceX is already 're-using' its stages. It's just that it has never re-used one that has not been strapped down to the ground. Given all of this, it would be MIGHTY strange if boosters that had flown could not be re-used.

If you're betting on this being the case, don't. You'll probably lose the bet.

It's best to describe Star Wars as fantasy transplanted into a sci-fi setting. Planets take the place of cities, spaceships take the place of ships, and lightsabers take the place of swords. And the Death Star takes the place of the Magical Weapon of Doom (The one ring, the ark of the covenant, the soul cube, etc.). But if you switch all of that back you still get a completely coherent story.

Sci-fi ranges the spectrum from 'hard' (completely plausible in princple) to 'soft' (sufficiently advanced technology), so you can't really say the presence of magic per se disqualifies something as sci-fi. Instead, it's what you do with the magic that counts. My personal interpretation is that good sci-fi should deal with the impact of technological developments on human society, ethics, and outlook on the future.

The whole thing felt like what would happen if you asked a jackass genie to give you a new star wars film like the originals. The genie laughs to himself and gives you The Force Awakens. Then tells you to be more careful with your next wish.

Star Wars is dead and has been dead for a long time. Deal with it.

If you look at the marketing around this movie, it was just incredible. J J Abrams was supposedly the "Best Director Ever"; a star wars fanboy and master genius. Even though he ruined Star Trek by being a bitch for his corporate masters and turning it into standard soulless Hollywood fare, don't worry! He loves Star Wars and he'll stay true to the spirit of it.

The real geniuses are the social media masters. The people who know what buttons to push and how to make things viral. They own the world now. They can sell us anything. That's the take-away lesson from this movie.

All the late night talk shows. Celebrity endorsements. Merchandising. Posters. Social media. Memes. Everyone who was 'in' on the story of the movie coming out and saying it was brilliant, amazing, and that the fans will love it. And the fans duly did what they were told and loved it

> It is amazing what a big marketing budget can do to brainwash consumers

The marketing was so pervasive that some people _need_ to believe that it was an amazing movie. They have to rationalize their beliefs and predictions for themselves.

They'll eventually come around to the truth, though.

Precisely.

The reason cold fusion isn't taken seriously is because it's been a consistent source of bullshit, lies, data manipulation, outright fraud, and bogus explanations.

Cold fusion didn't just lose credibility because of Fleischmann and Pons. It's lost credibility because of the 26 years of its history too. A lot of the time, reputable scientists do attempt to verify and duplicate the claims of the cold fusion people only to be rapidly turned away. The cold fusion people don't *want* real experts looking at their work. They want gullible idiots and journalists.

The shuttle program has nothing to do with this... virtually every design decision for the shuttle was different from the falcon 9.

The shuttle carried a huge non-reusable external fuel tank and the SRBs (which produced 70% of takeoff thrust) were also non-reusable. The 'main' engines were not really designed for re-use and had to be completely rebuilt after each flight. The decision to use heat tiles instead of an ablative coating meant the risk of heat tiles falling off and required very expensive refurb after each flight. The weird shape of the shuttle meant that the aerodynamics were complicated and hard to understand; Columbia was destroyed partly due to aerodynamic forces. There was no escape system in the event of failure. Much of the design was literally based on "let's get the initial program cost down so that it can be approved by congress and let people pay for our mistakes later."

The shuttle proved zip about re-usable spacecraft. It did, however, prove just how much can go wrong when you have a flawed design process based on impossible and conflicting design requirements and a manufacturing process based on pork and congressional approval.

Yes, a lot of people have proposed a plan like that, and it would in all likelihood work. But SpaceX's goals are more ambitious: They want to launch people on rockets that have been used many times. Knowing Musk, I'd bet $100 that he's going to achieve this goal.

You can - and people do - decommission nuclear reactors safely. That's not the point. The point is how much it costs to do so. Nuclear reactors are really expensive to safely decommission.

Although to be fair if you include the cost of damage to the environment that coal produces, then there's no comparison, coal is far far more expensive than any other form of power.

And MUCH easier than a nuclear plant.

> The bridge was torquing at it's center span's natural frequency x 2 (IIRC).

Link?

Nope, this isn't resonance, it's aeroelastic flutter: https://en.wikipedia.org/wiki/...

The important distinction is that resonance requires some oscillating energy input whereas flutter doesn't. Resonance doesn't directly depend on wind speed whereas flutter does.

To be fair, the article does a surprisingly bad job of explaining it, hence the confusion.

It's different. A resonant system has a particular frequency at which it 'likes' to oscillate; this frequency will have the lowest rate of energy dissipation, and so even a small amount of energy input at this frequency will tend to get stored and amplified over time. But in this bridge (FTA):

"When the bridge bounced up and down, as it did for months and earlier in the morning of November 7th, it's thought that the vortex street was causing forced harmonic motion on the bridge. But observations and calculations made by Farquharson about the speed of the wind and the motion of the bridge before it began to twist concluded that as the bridge approached collapse, the vortices were not being shed at the bridge's resonant frequency."

Our military interventions are not really about obtaining oil, or at least not directly. They are about keeping oil resources - and the huge influx of power and cash that comes with those resources - out of the hands of unfriendly actors like Saddam Hussein or Gaddafi.

That's what sometimes confuses people. Our wars in the ME are about oil, but not about _taking_ the oil. That part has to do with an entirely different dimension of our ME activity - our relationship with Saudi Arabia. Saudi Arabia provides a steady, reliable flux of oil into the world markets in return for the USA looking the other way when they commit heinous acts of human rights violations and terrorist support (including virtually open support for Al Qaeda and, up till recently, ISIS itself).

As long as Saudi Arabia remains friendly, we don't need anyone else's oil reserves in the ME because their reserves are pitifully small compared to Saudi Arabia's Ghawar field anyway.

> You are confusing natural gas production (which provides a significant amount of North American electrical generation and home utility) with light sweet crude oil production, which is what goes into the cars people drive to work, the tractor trailers that haul their consumer goods, and the airplanes they fly in. Middle Eastern oil prices have a HUGE impact on the American economy.

Uhm no I'm not. The USA gets 90% of its crude oil from either itself or non-OPEC countries. And of OPEC countries, the biggest contributor is Saudi Arabia, which still only supplies 8.1% of US oil. Less than one percent of oil imports come from Iraq. If they wanted to stop playing nice the US could easily make up for OPEC's entire contribution by ramping up domestic production. It's a myth that the USA is dependent on the ME for oil.

> I think there are many family members of the victims of the Bali nightclub bombings, 9/11 attacks, Charlie Hebdo slaughter, London Underground bombing, Paris 2015 attacks, and others who think that being dead is a "legitimate threat."

About 4000 people die of accidental fire-related incidents each year. Let's bomb fire.

You know, that's actually a pretty good analogy...