Daily Junction.mobi portal<p>The second unseen component is <a href="https://news.uchicago.edu/explainer/dark-energy-explained">dark energy</a>, which makes up around 70% of the universe. Its exact nature remains elusive, but dark energy is causing the expansion of the universe to accelerate. For decades, astronomers assumed that it is constant, or uniform. However, recent results hint that dark energy <a href="https://newscenter.lbl.gov/2025/03/19/new-desi-results-strengthen-hints-that-dark-energy-may-evolve/">could be changing over time</a>. Roman will put these competing ideas to the test.</p>
<p>If dark energy is constant, it points to a universe that keeps expanding forever. If dark energy changes, it could point to new physics beyond our current theories.</p>
<p>Roman may help address <a href="https://press.princeton.edu/books/paperback/9780691057842/critical-problems-in-physics">a longstanding puzzle</a>: why we observe the universe at a moment when the densities of matter and dark energy are roughly comparable. In the early universe, matter dominated. </p>
<figure class="align-center "> <img alt="Dark matter forms part of the underlying structure of the universe, known as the cosmic web." src="https://images.theconversation.com/files/735128/original/file-20260511-71-meky87.jpg?ixlib=rb-4.1.1&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/735128/original/file-20260511-71-meky87.jpg?ixlib=rb-4.1.1&q=45&auto=format&w=600&h=366&fit=crop&dpr=1 600w, https://images.theconversation.com/files/735128/original/file-20260511-71-meky87.jpg?ixlib=rb-4.1.1&q=30&auto=format&w=600&h=366&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/735128/original/file-20260511-71-meky87.jpg?ixlib=rb-4.1.1&q=15&auto=format&w=600&h=366&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/735128/original/file-20260511-71-meky87.jpg?ixlib=rb-4.1.1&q=45&auto=format&w=754&h=460&fit=crop&dpr=1 754w, https://images.theconversation.com/files/735128/original/file-20260511-71-meky87.jpg?ixlib=rb-4.1.1&q=30&auto=format&w=754&h=460&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/735128/original/file-20260511-71-meky87.jpg?ixlib=rb-4.1.1&q=15&auto=format&w=754&h=460&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"> <figcaption> <span class="caption">Dark matter forms part of the underlying structure of the universe, known as the cosmic web.</span> <span class="attribution"><a class="source" href="https://www.esa.int/ESA_Multimedia/Images/2025/06/Simulation_of_the_cosmic_web">Esa</a></span> </figcaption> </figure>
<p>In the far future, dark energy is expected to dominate completely. The present era appears to be a transition between the two – a cosmic intermission lasting billions of years, but brief in the lifespan of the universe.</p>
<p>This could be a <a href="https://arxiv.org/abs/astro-ph/0105317">simple coincidence</a> or a clue to new insights about the cosmos. For example, it could be that dark energy is changing over time, that gravity behaves differently on cosmic scales or that some ingredient is missing from our model of the universe. Distinguishing between these scenarios would require observations across huge spans of cosmic time – exactly the kind of data that Roman will provide.</p>
<h2>Beyond cosmology</h2>
<p>Roman’s science extends well beyond dark energy. It will carry out the largest survey yet of <a href="https://science.nasa.gov/mission/roman-space-telescope/exoplanets/">planets beyond our solar system</a>, detecting thousands of new worlds using a technique called gravitational microlensing.</p>
<p><a href="https://science.nasa.gov/mission/roman-space-telescope/microlensing/">Microlensing</a> happens when the gravity of a foreground star briefly bends and magnifies the light from a more distant background star – acting like a natural magnifying lens passing between us and a distant object. If the foreground star has a planet, that planet can create a small extra brightening in the signal, revealing its presence.</p>
<p>Many of these exoplanets would be difficult to find with the two most widely used techniques to discover exoplanets – the transit and radial velocity methods. Using microlensing, Roman could find planets in wide orbits, low mass planets and even free floating worlds that are not bound to any star.</p>
<p>Roman is also part of a new era of survey astronomy. Its wide-field capabilities place it alongside other major missions. The European Space Agency’s <a href="https://www.esa.int/Science_Exploration/Space_Science/Euclid">Euclid space mission</a> is mapping billions of galaxies to study dark matter and dark energy. The <a href="https://rubinobservatory.org/">Vera C. Rubin Observatory</a>, built on a mountaintop in Chile, will repeatedly scan the southern sky. </p>
<p>Together, these observatories will help astronomers map the universe across different wavelengths, distances and timescales.</p>
<p>Roman will also work together with the James Webb space telescope, identifying large-scale patterns and unusual objects across the sky, which Webb can then study in detail. This combination of breadth and depth is increasingly important in modern astronomy.</p>
<p>Roman’s greatest impact may come from the unexpected. With repeated observations of large areas of sky, it will detect rare events and previously unseen phenomena. For astronomers, this is one of the mission’s most exciting aspects.</p>
<p>By mapping the universe in unprecedented detail, the Roman telescope will provide a powerful test of our current understanding of cosmology – and potentially point the way to new physics.<!-- Below is The Conversation's page counter tag. Please DO NOT REMOVE. --><img src="https://counter.theconversation.com/content/281291/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important" referrerpolicy="no-referrer-when-downgrade" /><!-- End of code. If you don't see any code above, please get new code from the Advanced tab after you click the republish button. The page counter does not collect any personal data. More info: https://theconversation.com/republishing-guidelines --></p>
<p><span><a href="https://theconversation.com/profiles/noelia-noel-2408204">Noelia Noël</a>, Senior Lecturer, School of Mathematics and Physics, <em><a href="https://theconversation.com/institutions/university-of-surrey-1201">University of Surrey</a></em></span></p>
<p>This article is republished from <a href="https://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/nasas-new-space-telescope-will-tackle-some-of-the-universes-biggest-mysteries-281291">original article</a>.</p> </div>