There is a lot of room for improving balance in society; particularly so in STEM fields, where basic equality is often inaccessible to women and to people from oppressed castes, because of systemic problems.

GLASS CEILING is a term often applied to such systemic problems, and that's the solution to this bonus clue:

A couple of girls discussed closing unseen barrier (5,7)
G LASS {a couple of girls} CEILING {homophone of ("discussed ...") SEALING = closing}.

1a: EQUALITY. 1d: ETHICAL. 11a: BALANCE. 21a: ROLES. 23a: ME TOO.

The following solution entries are thematic for STEM (starred ones have thematic surfaces as well):

4d: TESLA*. 7d: SONAR*. 13a: WIRED. 17d: POLYTHENE. 19a: STEM. 25d: OZONE*. 28a: CAPACITOR*.

In addition, the "electromagnetic" surface of 6d is STEM-themed. The surface of 12a refers to the Cantor set, a fascinating mathematical structure.

The "champion of balance" whose name is "constituted" by rearranging the circled letters is the brilliant architect of the constitution of India, B. R. AMBEDKAR.

The puzzle celebrates two Indian women who overcame systemic challenges and are seen as pioneers in their STEM fields. Their names are hidden as ninas in the grid: botanist JANAKI AMMAL (10th column from the left and 6th row from the top) and meteorologist ANNA MANI (2nd row from the bottom).

This puzzle is a pangram (i.e., all 26 letters of the alphabet get used in the solution words, achieving another balance of sorts).

Many thanks to all the participants, listed here in order of points scored (and in order of submission timestamp when points were equal):

Saki,  Akshay,  Ganesh Nayak, 
Samit Kallianpur,  Shashwat S,  Supriya Mithal, 
Aashwina Mouli,  Mona Sogal,  Naru, 
Fran Gipani,  JASR,  N Anantakrishnan, 
Tejas Siddharth,  Saras VI Wing 1994,  P K Dwarakanath, 
Gussalufz Nahidosh,  Dr. S Venkatesh,  Veera Raghavan, 
Sowmya,  Nick Loader,  Ashit Hegde, 
BombayyaNYker,  N Rengaswamy,  Lakshmi Prakash, 
The Void,  Dark Knight,  R Nagendra Prasad, 
Vasant,  Atul Jairaj,  Annapoorani, 
Isorropia,  Swathi,  Dee, 
Vasanthi S,  Tapan / Taps / Tapi,  Prasand (Prasanna & Anand).

Here's a selection of comments and feedback from the solvers:

• Naru: Nice and easy, more on the easy side, but thoroughly enjoyable.
• Fran Gipani: Wonderful grid! Great clues! Thank you!
• The Void: 27 was mean to non-cricket fans, but I like it! :-) Other faves: 10, 12, 30, 3, 4.
• Saras VI Wing 1994: Thank you for the relevant, lovely and enjoyable crossword Gussalufz! We are Roopesh Mathur and Tapan Agrawal, living in Boston and London, respectively. We used to solve the Hindu and Express crosswords daily at IITM in our hostel wing. Now we solve crosswords over Whatsapp when we get the chance. The exemplars are tough but they need highlighting—very well done!
• Tapan / Taps / Tapi: Nice crossword. A bit tough. Got Help from Roopesh Mathur (1994 Batch, BTech, IIT Madras, Saras) for some of the clues.
• Isorropia: Ukulele and Ukelele—this crossword is accepting the second spelling. Hidden exemplar—difficult to understand your question.
• Saki: Nice and easy puzzle with a lot of thematic answers.
• Samit Kallianpur: Nice grid.
• Prasand (Prasanna & Anand): Loved the clues—our favorite being 6D in-law, took us back to Mardi Gras days. We also think ukulele (sic ukelele) is spelt wrong, not sure if this is an alternative spelling. Couldn't figure out the hidden exemplars, is glass ceiling correct?
• Shashwat S: Very enjoyable grid with beginner-friendly cluing devices that pays tribute to a lot of unsung heroes in STEM.
• Supriya Mithal: Excellent clues and surfaces and an enjoyable grid and theme. Look forward to more grids from you Gussalufz. Some favourites: 16A, 21A, 23A, 31A, 15D, 22D, 27D.
• Ganesh Nayak: Very pleasant solve, ninas are great! BR Ambedkar took me by surprise as a "champion of balance" then figured why not, if a bit oblique. Would've been extra special if a word pertaining to Janaki Ammal was clued (Anna Mani got "ozone")—or perhaps I missed it. Loved that 1A set the tone for the puzzle, making it immaculate!
• BombayyaNYker: Awesome GRID again. Always something to learn in Gussalufz GRIDS.
• Ashit Hegde: The quality of the grid always suffer when the setter is constrained by the demands of having to include the additional puzzle. Good fun however if one is not a purist.
• Mona Sogal: Wonderful grid... all the clues could be annotated perfectly... always enjoy your grids Gussalufz.
• JASR: Loved it! Nice incorporation of the theme and ninas, along with the pangram. And yes, this was easier than your usual fare in THC, but fun nevertheless. 27D would be my top pick.
• Sowmya: Good puzzle and theme.
• Veera Raghavan: Well constructed crossword with clues ingeniously crafted.
• Nick Loader: Wonderful wordplay, somehow = redundant. Surfaces: sameness = unnatural, Warsaw as G. I. Jozef, swap hands = unnatural, played with—surface works as 'electronic device' not 'musical instrument', if the latter 'electronic Spanish...', brew = unnatural, spurn = unnatural, rum up = unnatural, cricket surface bit vague. Other clues incredible 4 n 15a=#1 but more variety n difficulty pls. Gr8 bonus Qs.
• P K Dwarakanath: Very good concept and should become a regular feature... Maybe prizes also? Wishing IITM a Happy and Successful New Year 2022 scaling new heights of excellence...
• Dr. S Venkatesh: Well conceived. We need more such motivational puzzles which carry spirited message.
• Lakshmi Prakash: Wonderful grid with a very powerful theme.

We also asked solvers to submit a slogan on the theme of "Restoring Balance in STEM." The submissions were judged by IITMAA, and they determined these as the top three submissions:

• Saki: Let us all STEM the tide of women moving away from science
• Sowmya: Putting the "Sis" in the "Sy-STEM"
• Saras VI Wing 1994: Haiku by Roopesh Mathur:
  A stricken world needs diverse ideas and endeavours
  Women in STEM restore balance!

• Isorropia: We have to bring back and nurture BALANCE in STEM
  B - Brilliance in ideas and action
  AL - Alacrity of thought
  AN - Analytical mindset
  C - Child-like Curiosity
  E - Equality
• Aashwina Mouli: More women in STEM more role models for more women in STEM
• BombayyaNYker: EQUITY in ACCESS
• Mona Sogal: Do I sign up for equality? (6)
  do is party/ I into party/ sign up for as container indicator/ equality = parity
• Fran Gipani: STEMinist Power! Jai Bhim!
• Tapan / Taps / Tapi:
  Save the Planet
  Give us peace & Prosperity
  STEM is what began it
  STEM can bring the parity
  
• Atul Jairaj: Opportunities are limited, the biases are strong. On this 'restoring balance in STEM' day, let us right the wrong.
• P K Dwarakanath:
  More Women in STEM,
  And more power to them,
  Its not only Fair,
  But also a breath of Fresh Air,
  To blow the cobwebs away,
  And brighten the way...
• Gussalufz Nahidosh: Acceleration in progress from tapping the potential energy of the marginalized.
• Dr. S Venkatesh:
  Restore balance in STEM (Science, Tech, Engineering, Mathematics)
  Promote fresh thinking, new ideas and perspectives
  Encourage young women pursue STEM-related careers
  Empower them to break the glass ceiling
• Veera Raghavan: Restoring gender balance in STEM is entirely in the hands of women. Let more and more of them come out of the shell and shine.
• Dee: Normalize careers in social sciences.