In Star Trek IV, Scotty gives away the formula to the inventor of transparent aluminium. This aluminium, if my memory serves me, is to house the humpback whale they must procure from the past. Crazy, I know.

But why does the humpback whale need to be in a transparent container? I know it wouldn't be pleasant, but for the short few hours once they'd stolen it, but is that sufficient enough to justify simplifying your time in the past?

I realise from a previous question that Scotty thought he had to give the formula away, as the man they found was the inventor (Marcus Nichols). But until he found him he didn't seem to know he would find him, so that can't be sufficient reasoning to go looking for transparent aluminium.

Why did they need it?

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    Because the audience needs to see whales in a tank.
    – BBlake
    Commented May 3, 2012 at 19:34
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    Wouldn't it also help to see the whales so they could monitor them for problems? Make sure they weren't hurt or dead after maneuvering through space and around the sun and such? Commented May 8, 2012 at 20:44
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    @BartSilverstrim if they were injured, what would they do? Bones is a doctor, not a veterinarian!
    – AncientSwordRage
    Commented May 8, 2012 at 20:46
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    @Pureferret - Dump the injured whales back in the ocean, pick up another pair of humpback whales.
    – RobertF
    Commented May 9, 2014 at 19:26
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    @AncientSwordRage if he can figure out how to heal a Horta, I'm guessing he could at least attempt to fix up a fellow mammal.
    – Paul L
    Commented May 26, 2016 at 18:32

5 Answers 5


You recall incorrectly. They needed the large plexiglass panels to make the tank for the whales on the ship. They didn't have any money. But they have knowledge of advanced materials like transparent aluminum, which would be worth a great deal of money to that man and his company. So in exchange for the plexiglass for the whale tank, they provide him with the formula for transparent aluminum.

As far as I know, there's nothing the requires the tank have transparent walls, but given their limited resources, the crew needed some materials to build the tank. So if they didn't choose to use plexiglass, it would have been large metal walls or some other material, which they would have had to procure from someone, and they would have had the same lack of money problem.

  • 2
    Curse you Commander @Keen! Commented May 3, 2012 at 19:37
  • @JackBNimble Thanks for your answer, I had forgotten it was plexiglass.
    – user1027
    Commented May 3, 2012 at 19:38
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    To be fair, the dialog did confuse a lot of people on this plot point and the whole materials confusion.
    – Mufasa
    Commented May 4, 2012 at 18:10
  • Also, mass was going to be a problem, and sufficiently strong metal walls weigh a lot more than the plexiglass and would be difficult to procure in a contiguous piece of sufficient size. And having to weld it sealed would be very time consuming, as opposed to getting a nice light precut piece. Commented Jul 19, 2012 at 21:12
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    @TysonoftheNorthwest: I doubt this. Obviously metal is stronger on a strength to weight ratio. Otherwise all kinds of things that didn't need to be transparent would be made of plexiglass too and there would be a non-transparent Plexiglass product in common use. Plexiglass's distinguishing beneficial attribute is its transparency. Commented Apr 24, 2015 at 15:07

A review of the transcript shows that Scotty needed to bargain to purchase the 6-inch plexiglass used to hold the water. His bargaining chip to get that plexiglass is the secret to transparent aluminum.

SCOTTY Ah, what else indeed? Let me put it another way: how thick would a piece of your plexiglass need to be at 60 feet by 10 feet to withstand the pressure of 18,000 cubic feet of water?

NICHOLS That's easy: 6 inches. We carry stuff that big in stock.

SCOTTY Yes, I noticed. Now suppose -- just suppose -- I could show you a way to manufacture a wall that would do the same job but was only an inch thick. Would that be worth something to you, eh?

NICHOLS ... But it would take years just to figure out the dynamics of this matrix...!

BONES You'll be rich beyond the dreams of avarice.

SCOTTY So, is it worth something? Or should I just punch "clear"...

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    a +1 for explaining the future tech tip was bartered in exchange for the whaletanks plexiglass....and that it wasn't a clear aluminum whaletank. Commented May 4, 2012 at 0:29
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    It's not clear to me this actually shows they were only bartering and didn't then use the formula to make transparent aluminum. Commented Apr 24, 2015 at 15:09
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    @ThePopMachine "But it would take years just to figure out the dynamics of this matrix...!" He can't turn around and make the transparent aluminum tomorrow. And Scotty is interesting in holding 18,000 cubic feet of water right away, hence the 6" plexiglass. Commented Apr 24, 2015 at 16:06
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    @JackBNimble: "It would take years to figure out the dynamics of this matrix" could mean it would take years of his own, without whatever Scotty is showing them. Commented Apr 24, 2015 at 16:41
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    @ThePopMachine: They would still need the proper facilities in order to produce the new aluminum to the scale that Scotty would need, plus the raw materials. In a land without industrial-sized replicators, that's going to take some time and expense. It seems pretty clear that Scotty is trying to procure the plexiglass and is using the formula of the new aluminum as currency.
    – Ellesedil
    Commented May 26, 2016 at 21:22

In order to get something for free they gave away knowledge. The crew wouldnt get metal for free and being ethical they wouldn't steal metal from anywhere so they traded what they had, the knowledge to make the substance, in exchange for some of it.
Makes sense to me

  • 4
    The crew didn't get or steal metal, they traded the formula for a large sheet of plexiglass.
    – Valorum
    Commented Apr 23, 2015 at 21:12

According to an early draft of Star Trek IV, transparent aluminum was invented in the mid-2130s. The novelization (likely based on a later draft) indicates that Dr. Nichols is the credited inventor of the formula – Scott concludes that his being in San Francisco and needing transparent aluminum when this "breakthrough" occurs is a predestination paradox. So Scott had to give him the formula or risk altering the timeline


Out of universe clue... They were filming at the monterey bay aquarium, which is famous for the HUGE plexiglass panel in the main tank, which was laid under tight security to keep its trade secret ...secret.

  • 3
    I'm at a loss to understand how this answers the question asked.
    – Valorum
    Commented Mar 17, 2018 at 0:02

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