The frozen bubble: physics meets photography

Nicole Reynolds and Anika Chan

Australian Institute of Physics

Each year, the Australian Institute of Physics (AIP) holds multiple photography competitions to celebrate science photography and most importantly, the amazing physics illustrated by the striking images. The winners of each year’s competition have their photograph featured on the homepage of the AIP website or receives a cash prize.

Frozen bubble

The photograph of the frozen bubble (above) by Chad Clark, was the winner of the 2022 AIP National Photography Competition. Clarke’s inspiration for the photograph came from wanting to try his hand at making a frozen bubble photograph. Adding soap to water lowers its surface tension, which then allows it to be blown into a bubble. In the bubble, water molecules are sandwiched between two layers of lipids, which are a class of molecules that make up parts of soap. If the bubble itself stays intact long enough for the temperature of the water to fall below freezing, a phase change occurs and the water begins to form ice crystals. The point of formation of these ice crystals can happen randomly along the surface in multiple places simultaneously, but often initiates where the bubble touches an already ice-cold object. These crystals grow along the layer of water between the lipids and are initially still freely floating around. Once all water is frozen, the bubble retains its shape.

Clarke’s frozen bubble photograph was taken in his back garden, in the cold early morning in Canberra, Australian Capital Territory , Australia. He used a Canon 6d with a Tamron 90mm macro lens. Since the photo was taken in the early morning, a wide aperture was also used to account for low light conditions.

Aiden Baker-Gabb won the highly-coveted Grand Prize, in the 2022 ACT AIP Photography Competition for his Lagoon Nebula photograph (above). His Cygnus photograph won the Special Award for a School Student in the same competition.

Baker-Gabb was inspired to take these photographs through his interests in the night sky and his in astrophotography. He says that while he enjoys marvelling at telescope photos, he finds it “far more rewarding to get outside and uncover these beautiful structures for [himself]”. He regularly posts his astrophotography on his Instagram account, @abg_astrophotography.

The process of creating an astronomical photograph is complex, since a lot of space structures are outside the range we can see with our eyes. This means that the light that enters the camera needs to be edited and shifted into the visible light spectrum.

More photography

Nebulae are no exception. A nebula is a massive cloud of gas and dust from which stars form. Baker-Gabb’s two photographs depict the Butterfly Nebula in the Cygnus region, and the Lagoon Nebula.

On the right side of the Cygnus photograph we see a pale butterfly-shaped nebula which appears to be almost flying out of the picture. Surrounding the butterfly we have intricate networks of gas and dust, and the bright star Sadr, in the middle of the photograph. This star is the second brightest star in the constellation Cygnus. In the Lagoon Nebula photograph, a bright white core shines outwards into a cloud of blue gas. The youngest and most luminous stars are formed here and reside within this core. This central star forming region is surrounded by a border of green and copper gas, separating the nebula from a sea of surrounding stars.

Light from distant astronomical objects is very faint, so Baker-Gabb took 50-100 short exposures and stacked them to capture as much light as possible. He repeated this using three different filters which let through three unique ranges of light. These three filters target different chemicals present in the nebulae. In the Lagoon Nebula photo, doubly ionised oxygen appears bright blue, surrounded by green ionised sulphur and orange hydrogen. Ionisation occurs when an electron is knocked out of an atom, causing the atom to be slightly charged. Those same three chemicals are coloured yellow, orange and red in the Cygnus photograph. Both of the photographs are false colour images, meaning Baker-Gabb has full control over what colours the nebulae appear.

Baker-Gabb’s two winning photographs were taken using a WO 71mm GT APO triplet refractor on a Saxon HEQ5 Mount, from his balcony in Canberra ACT, Australia.

Dr John Long won a notable mention in the 2022 AIP National Photography Competition. His photo of Pinjarra the saltwater crocodile at Melbourne Aquarium is a beautiful example of total internal reflection (and a fantastic showcase of the joys of being a physicist).

In September 2017, Long was at the annual dinner for the Australian Conference for Science and Mathematics Education, which was being held at the Melbourne Aquarium. While seated at a dining table, Long saw Pinjarra out of the corner of his eye, beautifully reflected from the surface of the water. He rushed over and took some photos on his Nikon digital camera. In Long’s photograph, Pinjarra is looking up at the surface of the water, where we can see his reflected image, due to total internal reflection.

Total internal reflection is when light is completely reflected at the boundary between two transparent media. A transparent medium is a substance which light can travel through, such as glass, water or air. In the photo above the two media at the boundary are the water and the air.

Long says “it’s a really amazing image”. Long is a long-standing Member of the Australian Institute Physics (MAIP) who teaches first year physics at Deakin University in Australia, and over Zoom to physics students across the world.

If you’re interested in joining the AIP, click the link here. The AIP membership levels cater to physics enthusiasts, Australian students and professional physicists.

To participate in the 2023 AIP National Photography Competition, send your photograph to [email protected] by the 1st of November, being sure to include your Australian state/territory. Entrants must be Australian residents.