Five Open Questions After a Big Year in Space and Physics

Good science years do not end with answers. They end with better questions, and the last twelve months were a very good year. Here are five that will shape the next decade.

• Is dark energy weakening? DESI sees 2.8 to 4.2 sigma, but not five ^[1].
• What caused the LSND and MiniBooNE anomalies, now that a single sterile neutrino is ruled out at 95 percent? ^[2]
• How did black holes get so big so early? Webb’s little red dots keep the question alive ^[3].
• Can Roman and Rubin turn mysteries into measurements? Roman launched August 30, 2026; Rubin is already finding thousands of asteroids ^[4][5].

1. Is dark energy changing?

DESI’s analysis of nearly 15 million galaxies and quasars found 2.8 to 4.2 sigma evidence for evolving dark energy, short of the five-sigma discovery bar ^[1]. The next data release and independent surveys will decide whether it is a trend or a mirage.

2. What were LSND and MiniBooNE seeing?

MicroBooNE excluded a single sterile neutrino with 95 percent certainty, which means the simplest explanation is out and the original anomalies are unexplained ^[2]. Physics is back to asking what, besides a fourth neutrino, could have fooled two experiments.

3. How do black holes grow so fast?

Webb’s little red dots are early galaxies with massive active black holes, and a June 2026 report of a source apparently forming one suggests black holes may grow before their host galaxies mature ^[3]. One example is a clue, not a mechanism.

4. What will the new wide-angle eyes see?

The Roman Space Telescope launched August 30, 2026 with a camera about 1,000 times faster than Hubble’s, with first images expected by early 2027 ^[4]. Rubin has already logged over 11,000 new asteroids in early data ^[5]. Both machines are built for surveys, which means the surprises will come from statistics, not single pictures.

The five questions at a glance

It helps to see each open question next to the number that defines it. DESI’s evidence for evolving dark energy ranges from 2.8 to 4.2 sigma against a five-sigma bar ^[1]. MicroBooNE excluded a single sterile neutrino at 95 percent confidence, using 60 percent of its data and a collaboration of 193 scientists ^[2]. The little red dot caught in formation sits at redshift 6, magnified 16 times by lensing, in a galaxy in its first 10 million years ^[3]. Roman carries a 300-megapixel camera and returns 1.4 terabytes a day ^[4], and Rubin sent out 800,000 alerts on its first night and found more than 11,000 asteroids in early data ^[5].

The year also produced answers. Artemis II’s crew flew around the Moon and splashed down safely, with Orion’s heat shield enduring reentry as designed ^[6], and astronomers confirmed four small planets around Barnard’s Star, the nearest single star, using signals of 0.2 to 0.5 meters per second ^[7]. The pattern is that each answer depends on better instruments, and each of the five questions is waiting on one: more data for DESI, the next experiments of the short-baseline program for neutrinos, ALMA and JWST follow-up for red dots, and survey time for Roman and Rubin.

5. Where do we go next?

Artemis II flew four astronauts around the Moon and home in April 2026, with a crewed landing planned for 2028 ^[6]. Barnard’s Star, six light-years away, hosts four small planets that show how common rocky worlds may be, though these are too hot for life ^[7].

The common thread is that each of these questions is now answerable: with another year of data, another instrument, another team. That is the real state of the field. Not mystery for its own sake, but mystery with a deadline.

Questions readers ask

What are the biggest open questions in physics and astronomy right now?

Examples include whether dark energy is evolving, what caused the LSND and MiniBooNE anomalies, how early supermassive black holes formed, and what new survey telescopes will reveal ^{[1][2][3][4][5]}.