The 1934 film *The Thin Man* indeed feels more modern than many movies from the 1940s for several reasons:

### 1. **Witty and Fast-Paced Dialogue**
- *The Thin Man* features sharp, rapid-fire dialogue, especially between the lead characters Nick and Nora Charles (played by William Powell and Myrna Loy). This style of dialogue feels very contemporary and contrasts with the often more formal and melodramatic dialogue of many 1940s films. The humor and banter between Nick and Nora seem to anticipate the screwball comedies of later years, making the film feel ahead of its time.

### 2. **Progressive Portrayal of Gender Roles**
- The relationship between Nick and Nora Charles is notably equal and modern for its time. Nora is portrayed as Nick's intellectual equal, and their playful and respectful dynamic contrasts with more traditional and patriarchal relationships often depicted in the 1940s. Their partnership as a married couple who enjoy each other's company and engage in solving mysteries together feels fresh and more aligned with later depictions of relationships.

### 3. **Sophisticated Urban Setting**
- The film's setting in cosmopolitan New York, with its glamorous parties and sophisticated characters, exudes a sense of modernity. The urban, stylish environment and the characters' elegant, carefree lifestyles contribute to the film's contemporary feel, distancing it from the wartime or rural settings often seen in 1940s films.

### 4. **Lighthearted Tone Amidst Serious Themes**
- While *The Thin Man* is a murder mystery, it maintains a lighthearted and comedic tone throughout, blending genres in a way that feels modern. Many 1940s films, particularly during and after World War II, leaned toward more serious, dramatic, or noir themes, which can make them feel heavier and more dated by comparison.

### 5. **Pre-Code Hollywood Influence**
- *The Thin Man* was made during the Pre-Code era, just before the Hays Code (which imposed strict censorship on Hollywood films) began to be strictly enforced. As a result, the film includes more suggestive humor, playful innuendos, and a relaxed attitude toward drinking and gender roles than what would be allowed in later films of the 1930s and 1940s. This Pre-Code influence gives the film a certain edginess and freedom that was toned down in many later films, contributing to its modern feel.

### 6. **Timeless Performances**
- William Powell and Myrna Loy's chemistry is often cited as one of the film's most enduring qualities. Their performances feel natural and unforced, avoiding the more mannered acting styles that can make older films seem dated. Their charm and ease on screen help the film resonate with modern audiences.

### 7. **Pioneering of the Detective Genre**
- The film also helped to shape the detective genre, with Nick Charles as a laid-back but brilliant detective. This laid the groundwork for many detective films and TV shows that followed. While the 1940s saw the rise of darker film noirs, *The Thin Man*'s lighter take on the genre feels more aligned with modern crime comedies and mysteries.

In summary, *The Thin Man* feels more modern because of its witty dialogue, progressive portrayal of relationships, urban sophistication, light tone, Pre-Code influences, timeless performances, and pioneering approach to the detective genre. These elements combine to create a film that transcends its era and resonates with contemporary audiences.