Regarding the greenhouse effect: SF6 is very dense and doesn’t mix all that well with air which means it is found close to ground level which significantly limits its effectiveness as a greenhouse gas.

From what I’ve seen of Nathan’s posts in this and other threads, he will not admit that he was wrong about anything, in the same way that he will critique just about anything without providing sound reasoning for the critique and the sources to back up the critique.

The point is, I’m not “assuming” they faked it.

Hmm. If you aren’t assuming that they faked it, then I must have read your earlier comment wrong:

I suspect those tanks just had air in them, and they altered his voice electronically.

Maybe it’s just me, but that sounds like you are suspecting them of faking it. I don’t buy the deadline pressures. If that were the case, then the entire myth involving the SF6 would have been faked. While possible, it is not very plausible. Again, cheaper and faster, while a possible explanation, also is not plausible. Yes, producers want to find ways to keep costs down and production moving, but very rarely at the cost of quality. They buy the things that they need to do the experiments: they buy cars, tanks of compressed air and so on. I also figure that they pay some fees to have fire marshalls or other consultants help out with some of their more dangerous experiments. Compared to these, the cost of the SF6 bit is negligible.

I’m curious about your reasons for criticizing just about every post on here, either doubting some detail or claim, or simply voicing some critique of the grammar. Are you posting that way because you really doubt? Is it just to be the voice of doubt for doubt’s sake? Do you have something against Phil (and by extension the readers that post in support of him)? Or are you simply taking the role of troll, posting simply to get a rise out of people? Perhaps you are just trying to help people hone their debating skills, though the occasional ad hominem attacks you make don’t seem to support that rationale.

There is nothing wrong with doubt, as long as there is a rational reason for it. One must weigh the likelihood of the various possible outcomes or reasons. As far as inhaling SF6: possibility of passing out and falling over? Yes. Likely? Not if only a small amount is inhaled. Possibility of injury from falling? Yes. Serious, life-threatening or permanent? Not likely. As evidence of this, I offer a personal experience. While in college, I stood up very quickly in my dorm room and got a head rush, passed out, and woke up a couple seconds later on the carpet-covered concrete floor. By the slight headache, I had apparently bumped my head. I did not, however, suffer any broken bones, concussion, or any other serious injury. I admit, it’s just one person’s account, but it still stands as an example of what can happen.

In the end, though, it can be assumed that just about anything one sees on TV can be faked. However, just because something can be faked, doesn’t mean it was. Unless you have specific reasons and credible evidence to support your statement that you suspect that they faked it, there is little reason to make the claim, unless, of course, you just want to draw others into debate.

Sorry for the long-winded post, everyone, but I felt the need to address Nathan’s comments.

I understand that in some circles it’s considered rude to doubt whatever has just been made up, for the sake of convenience and comity. I prefer objective reasons, and let comity look after itself like an adult.

@Mark: I don’t care enough to ask the crew; I’m satisfied with not knowing. The evidence suggests you feel exactly the same, although no doubt you experience the “not knowing” a little differently. But it’s dishonest to talk now about asking the crew, when you were claiming earlier that I could resolve the matter by sucking SF6. Face red?

One more note. Just about everything that the Mythbusters do involves some measure of danger, even if they fake something. Just building some of the rigs involves the risk of serious injury. Having worked rather extensively around power tools myself, I can vouch for the respect they require.

By contrast, the clip where Adam alters his voice using helium and sodium hexafluoride shows an action which, when done correctly, has little to no risk of serious or permanent injury. Even if Adam had inhaled too much gas and passed out, as others have noted already, the body does quite well at expelling “bad air”. Even if he did pass out and did not come around on his own, I’m reasonably certain that they have a medical crew (or at least people in the shop, like Jaime, who are CPR certified) that could assist him in clearing his lungs, with no lasting damage.

So, the short of all this is, Adam would be far more likely to sustain serious injuries working with the tools in the shop than he would to suffer harm from the gases. Ergo, no reasonable risk of injury and no reason to fake it.

Perhaps you have some other compelling, rational reason that the clip could have been faked. However, the more I read your posts, the more you sound overly skeptical. In other words, you seem to doubt simply for the sake of doubting, rather than having truly logical reasons for those doubts.

The experiment can be done safely and without harm to the person performing it. That, alone, nixes your safety concern as a reasonable cause for faking it.

I was gonna say that I’d thought (I read it somewhere long ago) exactly what wb4 and others mentioned above, that it’s because on a less dense medium vocal cords vibrate at a higher rate, but then Courtney had this to say:

wb4: The real reason that people’s voices change when inhaling various gasses is that the changing speed of sound changes the resonant properties of the vocal tract, because the resonant frequency of a tube is proportional to the speed of sound. See this Wikipedia page (specifically the “Open” section) for more information.

I didn’t quite get that wiki link. I don’t read numbers that well. Anyone care to follow up? Thanks.

@Todd W: The potential danger is a realistic reason to use audio manipulation instead. It doesn’t mean they necessarily faked it, or that they didn’t. They’re as apparently up-front as they feel their credibility requires; we have no independent measure of how up-front they really are. Remember, it’s entertainment, not science. If it was faked, that doesn’t mean they’re “lying”. It’s just TV, so anything goes. It doesn’t really matter, but it’s equally as legitimate to doubt as to believe.

Yes, the Mythbusters fudge things sometimes. But, they are usually pretty up front about their fudging. They explain about what they are doing and how they build things. It’s typically where there is some extreme danger in telling what they’re doing that they hide the details (e.g., mixing up highly combustible fertilizer or making gunpowder).

While your hyperskepticism may lead you to doubt this clip, there is no realistic reason for them to have used any audio manipulation to change Adam’s voice, other than the use of the gas itself.

Now, SF6 isn’t completely inert. Around strong electrical discharges (especially coronal discharge), it’ll reorganize into disulfur decafluoride (S2F10), which is something like phosgene in toxicity.

The fluorine decomposition means that SF₆ is used as an dry (i.e. plasma assisted) etchant in semiconductor industry. As HF etches glass, fluorine compounds can etch oxides (for example, silicon dioxide on silicon wafers).