Someone may need to sing "Soft Kitty" to Sheldon after this.

"The Big Bang Theory" is a show deeply rooted in science. The series follows the lives of young scientists, there are actual scientists checking facts on the show and Mayim Bialik, aka Amy Farrah Fowler, is a scientist in real life. (Coldplay's "The Scientist" is sad we didn't mention it in that last sentence, so here's a cursory hat tip.)

Now in its eighth season, fans have come to know and love the characters, but it may be surprising to some that huge questions are still unanswered, and there's nothing science can do about it. According to interviews from the show's creators, it appears Sheldon may even discover everything there is to know about Dark Matter before we get the answers.

Here are seven "Big Bang Theory" mysteries science can't explain:

1. Will the elevator ever get fixed?

In a Season 3 episode, "The Staircase Implementation," it's revealed that the elevator was broken during one of Leonard's experiments with rocket fuel. This happened before Penny moved in, and it has been that way ever since.

Because the elevator is out of operation, staircase scenes have become a big part of the show, with the actors saying guests are always interested in the stairs. Even so, episodes have shown various characters attempting to use the elevator. Howard even tried to fix it. According to comments made at Comic Con and tweeted out by the Twitter account for "The Big Bang Theory," it looks like a repair isn't coming anytime soon:

Are you going to fix the elevator: I think those stairs are the only exercise those guys get. -@SteveMolaro#WBSDCC — The Big Bang Theory (@bigbangtheory) July 25, 2014

2. What does Howard's mom look like?



Image: YouTube



One of the running gags on the show is that you never actually get to see Howard's mom. You can only identify her from her off-screen yelling.

The series isn't completely devoid of Mrs. Wolowitz. The show has included a scene where her arms are visible when she pulls Raj back into her house (seen above), the writers have revealed that an overhead shot of Howard and Bernadette's wedding shows Mrs. Wolowitz as a "big pink blob" and there are some pictures in the Wolowitz household fans say reveal her face.

Carol Ann Susi in "Grey's Anatomy"

In real life, actress Carol Ann Susi voices the character, but she has reportedly said that the producers don't plan on showing her, so it is unknown if she would also be the visual representation of Mrs. Wolowitz or not.

3. Why does everybody hate Aquaman?

"The Big Bang Theory" tells us that "Aquaman sucks," but we never really get a reason why. The Justice League costume Raj wears doesn't allow him to ride on Howard's scooter, but is that really the reason for so much disdain?

At Comic Con, the writers were confronted about the reason for the Aquaman hate by the granddaughter of the Aquaman creator, but there wasn't much of an explanation.

4. What's the meaning behind Howard's alien pin?

Besides skinny jeans and a wide variety of belt buckles, one of Howard's signature items is an alien lapel pin. Various interviews confirm this is a significant item, but the story behind it has yet to be revealed.

The actor who portrays Howard, Simon Helberg, explained the mystery to TV Guide:

Only our costumer and I know its meaning. Ha-ha-ha. It's not a dirty secret, just a juicy one.



5. How did Sheldon come up with Bazinga?

Sheldon's catchphrase has become so popular that now it's even the name for a type of bee. In real life, the word was first used at the show by former "Big Bang Theory" writer Steve Engel, who would say it after pulling pranks.

We know Sheldon uses the word, which first appears in the Season 2 episode "The Monopolar Expedition," as a way to let everyone know when he said a joke, but the show hasn't yet revealed how he came up with the word.

6. What was in the letter from Howard's father?

In a Season 6 episode, "The Closet Reconfiguration," Sheldon discovers a letter addressed to Howard for his 18th birthday. It's from Howard's father, who walked out on him when he was young. Howard destroys the letter before reading it, but Sheldon looked at the contents and the gang decides to each tell Howard a version of what was in the letter, with only one being true. The true story is never revealed.

There have been different theories as to which story about the letter is true, but the only one we can be sure about is that Sheldon's version is probably wrong (and just because his was the plot of "The Goonies" and he later changed it).

7. What is Penny's last name?

This is perhaps the biggest mystery of all and the source of the most fan speculation. We're in Season 8 now and Penny's last name still hasn't been officially released. In an interview with Vulture, executive producer Steven Molaro left us wondering if it ever would be:

What name could we possibly pick that would be satisfying at this point? You know, I don't think we will [reveal it]. We're kind of a superstitious lot here. We've made it this far without knowing Penny's last name. I think we're good not finding out.